WO2025078981A1

WO2025078981A1 - Medical gases conduit

Info

Publication number: WO2025078981A1
Application number: PCT/IB2024/059892
Authority: WO
Inventors: Kieran James Hatcher; Anthony James Newland; Bhuvan GARG; Leo McKenzie RODGER; Thomas James Edwards; Hung Yan Daniel YAU
Original assignee: Fisher and Paykel Healthcare Ltd
Current assignee: Fisher and Paykel Healthcare Ltd
Priority date: 2023-10-11
Filing date: 2024-10-10
Publication date: 2025-04-17
Anticipated expiration: 2026-04-11

Abstract

A medical gases conduit includes an elongate tube which may be formed from a breathable material. The medical gases conduit includes one or more features to inhibit expansion or improve one or more of a crush resistance or crush recovery of the elongate tube. The medical gases conduit may include a reinforcement member. The medical gases conduit may be tethered to another medical gases conduit by a plurality of retainers. The elongate tube may have a modified corrugation profile. The medical gases conduit may include a membrane formed from a breathable material. The elongate tube may be formed from a composite material.

Description

MEDICAL GASES CONDUIT

[0001] This application claims the benefit of priority from United States Provisional Patent Application No. 63/589,526, entitled "MEDICAL GASES CONDUIT" and filed October 11, 2023, which is incorporated herein by reference in its entirety.

BACKGROUND

Field

[0002] The present disclosure relates to medical gases conduits for use in conveying medical gases in a medical gases system. More particularly, though not exclusively, the disclosure relates to a medical gases conduit including a breathable material which is permeable to water molecules, for use in a respiratory breathing circuit of a respiratory assistance system, an anesthesia breathing circuit of an anesthesia breathing system, or a surgical insufflation circuit of a surgical insufflation system.

Description of Related Art

[0003] Depending on the source (e.g., ambient air, a compressed gas cylinder, or a hospital supply), medical gases received by a medical gases system may have a temperature of less than about 25 ⁰ Celsius (°C), less than about 20 °C, or less than about 15 °C. And a relative humidity of less than about 50%, less than about 25%, less than about 10%, or less than about 5%.

[0004] There may be clinical benefits in heating and/or humidifying the flow of medical gases supplied to the patient.

[0005] In a respiratory assistance system or an anesthesia breathing system, it may be beneficial to heat and humidify a flow of respiratory gases to emulate the temperature and humidity which occur naturally in the lungs of a healthy human. Which may be about 37° Celsius (°C) and/or 100% relative humidity. The flow of respiratory gases may be heated and/or humidified towards, or to, these levels.

[0006] In a surgical insufflation system, it may be beneficial to heat and humidify a flow of insufflation gas supplied to a patient's abdominal or peritoneal cavity, e.g., during a laparoscopic procedure. Heating and/or humidifying the insufflation gas may decrease cellular damage or desiccation, limit adhesion formation, or reduce other deleterious effects.

[0007] In medical gases systems, the flow of medical gases may be conveyed to and/or from the patient by one or more conduits. [0008] A conduit may have a tube wall defining a lumen for passage of the medical gases. The temperature of the tube wall may be influenced by one or more of the temperature of the ambient air, movement of the ambient air, sunlight upon the tube wall, or any bed coverings laying upon the conduit, for example.

[0009] A temperature difference between the medical gases and the tube wall may cause the flow of medical gases to cool as it passes along the length of the conduit. If the temperature of the medical gases falls to the dew point, water vapor in the medical gases may condense into liquid water, forming condensate within the lumen.

[0010] In some examples, e.g., in a hospital environment, one or more of the temperature or humidity of the ambient air may be regulated, e.g., by a heating, ventilation and air conditioning (HVAC) system. In other examples, e.g., in a patient's home, one or more of the temperature and humidity of the ambient air may be unregulated. And may fluctuate during the day and/or with the seasons.

[0011] Condensate may alternatively or additionally form in other components of the medical gases system upstream or downstream of the conduit. For example, in a respiratory assistance system, respiratory gases conveyed to a ventilator or anesthesia machine by an expiratory conduit may cause condensate to form within the ventilator or anesthesia machine. The condensate may accumulate in a filter or on a flow sensor within the ventilator or anesthesia machine.

[0012] And condensate or other liquids may drain into a conduit from other components of the medical gases system, e.g., one or more of a filter, nebulizer, Y- piece, catheter mount, or patient interface.

[0013] Condensate or other liquids in a conduit or other component of the medical gases system may cause a variety of problems, such as one or more of:

• false sensor readings;

• saturation of filters;

• alarms (e.g., audible and visual);

• damage to the ventilator, anesthesia machine or components thereof (e.g., flow sensors);

• the need for periodic draining; or

• occlusion of the flow path.

BRIEF SUMMARY

[0014] In a first aspect, a medical gases circuit kit for use in conveying a flow of medical gases in a medical gases system may include: an inlet conduit; an outlet conduit configured to be fluidly coupled with the inlet conduit, at least a portion of the outlet conduit configured to expand more than the inlet conduit in at least a longitudinal direction, in use; and a plurality of retainers, each of the plurality of retainers configured to retain a portion of the inlet conduit and a portion of the outlet conduit to tether the outlet conduit to the inlet conduit, the plurality of retainers in combination with the inlet conduit configured to inhibit expansion of at least a portion of the outlet conduit in the longitudinal direction, in use.

[0015] In a second aspect, a medical gases circuit kit for use in conveying a flow of medical gases in a medical gases system may include: an inlet conduit; an outlet conduit, the outlet conduit may include a breathable material; and a plurality of retainers, each of the plurality of retainers may include a pair of retaining members, one of the pair of retaining members configured to receive and retain a portion of the inlet conduit and the other of the pair of retaining members configured to receive and retain a portion of the outlet conduit to tether the outlet conduit to the inlet conduit.

[0016] The following optional features apply to each of the first aspect and the second aspect.

[0017] The plurality of retainers may include: at least 2 retainers, at least 3 retainers, between 2 and 120 retainers, between 3 and 60 retainers, between 4 and 40 retainers, or one retainer for between every 4 and 50 corrugations of the outlet conduit.

[0018] The plurality of retainers may be configured to: engage the inlet conduit at a plurality of discrete locations along a length of the inlet conduit, and/or engage the outlet conduit at a plurality of discrete locations along a length of the outlet conduit.

[0019] At least one of the plurality of retainers may be configured to inhibit expansion of the outlet conduit in a radial direction, in use, by surrounding at least a majority of a circumference of a portion of the outlet conduit.

[0020] Absorption of water molecules by the outlet conduit, in use, may cause the outlet conduit to expand in a radial direction intermediate a consecutive pair of the plurality of retainers.

[0021] The plurality of retainers may each be configured to retain respective portions of the inlet conduit and the outlet conduit in a side-by-side relationship.

[0022] The plurality of retainers may each be configured to retain respective portions of the inlet conduit and the outlet conduit substantially adjacent to each other, so that the outlet conduit is, at least in part, heated by the inlet conduit, in use. [0023] The plurality of retainers may each be configured to engage one or more of: the inlet conduit so as to inhibit movement along a length of the inlet conduit, and/or the outlet conduit so as to inhibit movement along a length of the outlet conduit.

[0024] The inlet conduit may include a plurality of corrugations, each of the plurality of retainers configured to engage one or more of the plurality of corrugations of the inlet conduit; and/or the outlet conduit may include a plurality of corrugations, each of the plurality of retainers configured to engage a one or more of the plurality of corrugations of the outlet conduit.

[0025] The plurality of retainers each may include: a first clip configured to removably fit about the portion of the inlet conduit; and a second clip configured to removably fit about the portion of the outlet conduit.

[0026] The first clip may be part-annular and define an opening through which the inlet conduit is configured to be removably received, and/or the second clip may be partannular and define an opening through which the outlet conduit is configured to be removably received.

[0027] One or more of the plurality of retainers may be configured to be connected with one or more others of the plurality of retainers by a mechanical connection.

[0028] The mechanical connection may include one or more of: a snap-fit connection, a pivotable connection, or a ball-and-socket connection.

[0029] The plurality of retainers may each include: a first connector; and a second connector, the second connector configured to establish a mechanical connection with the first connector of another of the plurality of retainers.

[0030] The plurality of retainers may each include an arm, and : a distal end of the arm may include the first connector; and/or a proximal end of the arm may include the second connector.

[0031] The first connector may include a ball connector and the second connector may include a socket, the ball connector configured to establish a ball-and-socket connection with the socket of another of the plurality of retainers, and/or the socket configured to establish a ball-and-socket connection with the ball connector of another of the plurality of retainers.

[0032] The plurality of retainers may each be substantially identical.

[0033] Each of the plurality of retainers may be integrally formed, e.g., from a polymer material. [0034] The inlet conduit may include a heater, e.g., a heating wire.

[0035] The plurality of retainers may each be configured to: inhibit expansion of the portion of the outlet conduit in a radial direction when the outlet conduit is in one or more of a conditioned state or a saturated state; and/or not inhibit expansion of the portion of the outlet conduit in a radial direction when the outlet conduit is in one or more of a dry state or an equilibrated state.

[0036] The outlet conduit may include a length, in an equilibrated state, of between about 0.8 meters (m) and 2.5 m, and optionally: between about 0.8 m and 1.4 m, or between about 1.0 m and 1.4 m, e.g., about 1.2 m; or between about 1.2 m and 2.0 m, or between about 1.4 m and 1.8 m, e.g., about 1.6 m.

[0037] The medical gases circuit kit may not include at least one, and optionally both, of: a heater, e.g., a heating wire or a water jacket, configured to be used with the outlet conduit; or a water trap configured to be used with the outlet conduit.

[0038] The outlet conduit may include an elongate tube, the elongate tube including a breathable material which, in use, expands in one or more of a radial direction or the longitudinal direction due to absorption of water molecules.

[0039] The breathable material may include a block copolymer, the block copolymer optionally including one or more of: hard segments of polybutylene terephthalate; or soft segments of an ether type macro glycol.

[0040] The outlet conduit may include an elongate tube, the elongate tube configured to absorb at least 33%, between about 33% and 200%, between about 100% and 160%, between about 120% and 140%, or between about 130% and 135%, e.g., about 133%, of its own mass in water molecules, in immersion testing.

[0041] The outlet conduit may include an elongate tube, the elongate tube configured to expand by at least 20%, between about 20% and 70%, between about 25% and 50%, or between about 30% and 50% in at least one, and optionally each, of the radial direction or the longitudinal direction, in immersion testing.

[0042] The medical gases circuit kit may be a respiratory breathing circuit kit, the medical gases system may be a respiratory assistance system, the inlet conduit may be an inspiratory conduit, and the outlet conduit may be an expiratory conduit.

[0043] The medical gases circuit kit may further include any one or more of: a humidifier supply conduit, a pressure relief valve, a humidification chamber, a Y-piece, a catheter mount, a patient interface, a conduit hanger, a filter, or a pressure regulator. [0044] The medical gases circuit kit may be an anesthesia breathing circuit kit, the medical gases system may be an anesthesia breathing system, the inlet conduit may be an inspiratory conduit, and the outlet conduit may be an expiratory conduit.

[0045] The medical gases circuit kit may be a surgical insufflation circuit kit, the medical gases system may be a surgical insufflation system, the inlet conduit may be a delivery conduit, and the outlet conduit may be a discharge conduit.

[0046] Other technical features may be readily apparent to one skilled in the art from the following description, claims and figures.

[0047] In a third aspect, a medical gases conduit for use in conveying a flow of medical gases in a medical gases system may include: an elongate tube defining a lumen for passage of the flow of medical gases, at least a portion of the elongate tube including a breathable material which, in use, is configured to expand due to absorption of water molecules; a pair of connectors provided at respective ends of the elongate tube, the pair of connectors configured for pneumatically coupling the medical gases conduit with other components of the medical gases system; and a reinforcement member configured to engage the elongate tube at least at a plurality of discrete locations along a length of the elongate tube intermediate the pair of connectors, the reinforcement member configured to: impede expansion of at least a portion of the elongate tube in one or more of a radial direction or a longitudinal direction; and/or improve one or more of a crush resistance or a crush recovery of at least a portion of the medical gases conduit.

[0048] The reinforcement member may be fixedly attached to the pair of connectors.

[0049] The reinforcement member may be located, at least in part, within the lumen of the elongate tube.

[0050] The reinforcement member may include a helical shape.

[0051] The reinforcement member may be fixedly attached to the elongate tube at one or more locations along the length of the elongate tube intermediate the pair of connectors.

[0052] The reinforcement member may be fixedly attached to one or more of the pair of connectors or respective ends of the elongate tube.

[0053] The reinforcement member may be configured to: bias the elongate tube to a predetermined length, the predetermined length optionally being about equal to a length of the elongate tube in an equilibrated state, and/or be in tension when the elongate tube is in a conditioned state, in use. [0054] The reinforcement member may be formed, at least in part, from one or more of: a malleable alloy material, and/or a polymer material such as polypropylene.

[0055] The reinforcement member may be configured to wick condensate or other liquid within the lumen, in use.

[0056] The reinforcement member may include one or more grooves configured to wick the condensate or the other liquid by capillary action, at least in part.

[0057] The reinforcement member may include a longitudinal portion and a plurality of radial portions, each of the plurality of radial portions extending outwardly from the longitudinal portion and configured to engage a respective portion of the elongate tube or the pair of connectors.

[0058] The longitudinal portion may be disposed at or about a center of the lumen.

[0059] The elongate tube may be corrugated and one or more of the plurality of radial portions may be configured to engage a respective corrugation of the elongate tube, e.g., with a friction fit or an interference fit.

[0060] The reinforcement member may be located, at least in part, outside the elongate tube, e.g., substantially concentrically about the elongate tube.

[0061] The reinforcement member may include a double helix structure.

[0062] The reinforcement member may include an openwork structure.

[0063] The openwork structure may be formed, at least in part, from an elastomeric material.

[0064] The openwork structure may include: a plurality of annular members, the plurality of annular members disposed substantially coaxially and spaced apart along a length of at least a portion of the elongate tube; and a plurality of longitudinal members, the plurality of longitudinal members each extending between respective consecutive pairs of the plurality of annular members.

[0065] The elongate tube may be corrugated and one or more of the plurality of annular members may be configured to engage a respective corrugation of the elongate tube when the medical gases conduit is in one or more of an equilibrated state or a conditioned state.

[0066] The plurality of longitudinal members may be rotationally offset between two or more consecutive pairs of the plurality of annular members. [0067] openwork structure may be formed at least in part from one or more of: a polymer material such as polypropylene, and/or a malleable alloy.

[0068] The reinforcement member may be formed, at least in part, from a shapememory material.

[0069] The reinforcement member may be configured to be deformed by a temperature change of the elongate tube, in use.

[0070] The reinforcement member may be malleable.

[0071] The reinforcement member may include a sheath, wherein the sheath is not braided.

[0072] The sheath may be configured to conform, at least in part, to an outer surface of the elongate tube when the medical gases conduit is in an equilibrated state.

[0073] The elongate tube may be corrugated, and the sheath may be configured to conform to outer peaks of an outer surface of the elongate tube when the medical gases conduit is in an equilibrated state.

[0074] The reinforcement member may be embedded within the elongate tube.

[0075] Other technical features may be readily apparent to one skilled in the art from the following description, claims and figures.

[0076] In a fourth aspect, a medical gases conduit for use in conveying a flow of medical gases in a medical gases system may include: a membrane, the membrane including a breathable material which, in use, is configured to expand due to absorption of water molecules; and an elongate tube, the elongate tube: arranged substantially concentrically with respect to the membrane, fixedly attached to the membrane at a plurality of discrete locations along a length of the elongate tube, configured to support the membrane, configured to be permeable to water molecules, and configured to inhibit expansion of at least a portion of the membrane in at least one of a radial direction or a longitudinal direction, in use.

[0077] The membrane may at least in part define a lumen for the flow of medical gases.

[0078] The elongate tube may be directly attached to the membrane at a plurality of discrete locations along the length of the elongate tube.

[0079] The medical gases conduit in some examples may not include a rib, e.g., a helical rib, between the membrane and the elongate tube. [0080] The elongate tube may be a corrugated elongate tube.

[0081] The membrane may be directly attached to, and span between, outer peaks outside the corrugated elongate tube or inner peaks within the corrugated elongate tube.

[0082] The membrane may have a wall thickness of less than about 200 micrometers (pm), less than about 100 pm, less than about 80 pm, less than about 60 pm, less than about 40 pm, or about 20 pm.

[0083] The elongate tube may be arranged substantially concentrically about the membrane.

[0084] The membrane may be configured to extend between adjacent inner peaks on an inner surface of the elongate tube.

[0085] The membrane may form a substantially smooth bore of the medical gases conduit.

[0086] The membrane may be arranged concentrically about the elongate tube.

[0087] The membrane may be configured to extend between adjacent outer peaks on an outer surface of the tube.

[0088] The elongate tube may be porous, e.g., perforated.

[0089] The membrane and the elongate tube may be co-extrusions.

[0090] The membrane and the elongate tube may include dissimilar materials.

[0091] Other technical features may be readily apparent to one skilled in the art from the following description, claims and figures.

[0092] In a fifth aspect, a medical gases conduit for use in conveying a flow of medical gases in a medical gases system may include an elongate tube, the elongate tube at least in part formed from a composite material, the composite material including: a polymer matrix and a reinforcement material.

[0093] The polymer matrix may include a breathable material.

[0094] The composite material may include a fiber reinforced polymer; and/or the reinforcement material may include a fiber reinforcement. [0095] The fiber reinforcement may include one or more of: synthetic fibers, e.g., one or more of carbon fibers, glass fibers, or aramid fibers; or natural fibers, e.g., one or more of cellulose fibers, jute fibers, flax fibers or hemp fibers.

[0096] A volume fraction of the fiber reinforcement may be between about 5% and 60%, between about 10% and 50%, between about 20% and 40%, or about 30% of the elongate tube, in one or more of a dry state or an equilibrated state.

[0097] The fiber reinforcement may have an average diameter of between about 3 pm and 20 pirn.

[0098] Fibers of the fiber reinforcement may include a fiber sizing.

[0099] The reinforcement material may include discontinuous fibers.

[0100] The discontinuous fibers may include one or more of: an average length of less than about 25 millimeters (mm), or less than about 5 mm; an average length of at least 0.5 mm, between about 0.5 mm and 10 mm, or between about 1 mm and 5 mm, e.g., about 1.5 mm or about 3 mm; an average diameter of between about 5 pirn and 30 pirn, or between about 10 pirn and 20pim, e.g., about 15 pirn; or an aspect ratio above a critical fiber length for the polymer matrix.

[0101] The discontinuous fibers may be randomly aligned; the discontinuous fibers may be aligned in a circumferential direction; the discontinuous fibers may be aligned in a longitudinal direction; or between about 20% and 100%, or up to about 80% of the discontinuous fibers may be aligned with each other, e.g., in one of the circumferential direction or the longitudinal direction.

[0102] The reinforcement material may include continuous fibers, the continuous fibers optionally spanning one or more of a length or a circumference of the elongate tube.

[0103] The continuous fibers may include a fabric, e.g., a woven, knitted, mat, or braided preform.

[0104] The continuous fibers may be aligned in one or more directions.

[0105] The continuous fibers may be partially embedded in the elongate tube.

[0106] In a sixth aspect, a medical gases conduit for use in conveying a flow of medical gases in a medical gases system may include: an elongate tube defining a lumen for passage of the flow of medical gases; and a pair of connectors provided at respective ends of the elongate tube, the pair of connectors configured for pneumatically coupling the medical gases conduit with other components of the medical gases system, a connector of the pair of connectors comprising a pair of apertures.

[0107] The pair of apertures may be diametrically opposed.

[0108] The pair of apertures, in combination, may extend around more than 80% of a circumference of the connector.

[0109] The medical gases conduit may include a sheath provided about an outer surface of the elongate tube.

[0110] The sheath may be a braided sheath.

[0111] The sheath may be exposed through the pair of apertures.

[0112] The sheath may be fixedly attached to the elongate tube by the connector.

[0113] The connector may be overmolded, at least in part, to the sheath and the elongate tube.

[0114] The connector may be formed in two parts.

[0115] The connector may include: a first part which is injection molded, and a second part which is overmolded to the first part.

[0116] The second part may be overmolded to the first part, the elongate tube, and a sheath provided about an outer surface of the elongate tube.

[0117] Other technical features may be readily apparent to one skilled in the art from the following description, claims and figures.

[0118] The medical gases conduit of any one of the third to sixth aspects may have a length, in an equilibrated state, of between about 0.8 m and 2.5 m, and optionally: between about 0.8 m and 1.4 m, or between about 1.0 m and 1.4 m, e.g., about 1.2 m; or between about 1.2 m and 2.0 m, or between about 1.4 m and 1.8 m, e.g., about 1.6 m.

[0119] The medical gases conduit of any one of the third to sixth aspects in some examples may not include at least one, and optionally both, of: a heater, e.g., a heating wire or water jacket; or a water trap.

[0120] At least a portion of the medical gases conduit of any one of the third to sixth aspects may include a breathable material which, in use, is configured to expand in one or more of the radial direction, the longitudinal direction, or a wall thickness due to absorption of water molecules.

[0121] The elongate tube of any one of the third to sixth aspects may be configured to absorb at least 33%, between about 33% and 200%, between about 100% and 160%, between about 120% and 140%, or between about 130% and 135%, e.g., about 133% of its own mass in water molecules, in immersion testing.

[0122] The elongate tube of any one of the third to sixth aspects may be configured to expand by at least 20%, between about 20% and 70%, between about 25% and 50%, or between about 30% and 50% in at least one, and optionally each, of the radial direction or the longitudinal direction, in immersion testing.

[0123] The breathable material of any one of the third to sixth aspects may include a block copolymer, the block copolymer optionally including one or more of: hard segments of polybutylene terephthalate; or soft segments of an ether type macro glycol.

[0124] The medical gases system may be a respiratory assistance system, and the medical gases conduit of any one of the third to sixth aspects may be an expiratory conduit configured to convey respiratory gases away from a patient, in use.

[0125] The medical gases circuit kit may include the medical gases conduit of any one of the third to sixth aspects, and any one or more of: a humidifier supply conduit, a pressure relief valve, a humidification chamber, an inspiratory conduit, a plurality of retaining members, a delivery conduit, a Y-piece, a catheter mount, a patient interface, a conduit hanger, an expiratory conduit, a discharge conduit, a filter, or a pressure regulator.

[0126] The medical gases system may be an anesthesia breathing system, and the medical gases conduit of any one of the third to sixth aspects may be an expiratory conduit configured to convey respiratory gases away from a patient, in use.

[0127] The medical gases system may be a surgical insufflation system, and the medical gases conduit of any one of the third to sixth aspects may be a discharge conduit configured to convey insufflation gas away from a patient, in use.

[0128] Other technical features may be readily apparent to one skilled in the art from the following description, claims and figures.

[0129] Further aspects, novel features and advantages of the present disclosure will be readily apparent to those skilled in the art in light any one or more of the illustrative examples set out in the following detailed description and drawings. The detailed description and drawings are to be regarded as illustrative in nature, and not restrictive. Modifications or improvements may be made without departing from the spirit or scope of the disclosure and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0130] To easily identify the discussion of any particular element, the most significant digit or digits in a reference numeral refer to the figure number in which that element is first introduced.

[0131] Examples are described in further detail below with reference to the accompanying drawings, in which:

[0132] FIG. 1 is a schematic diagram of an example respiratory assistance system.

[0133] FIG. 2 is a schematic diagram of a humidifier which may be used in the respiratory assistance system of FIG. 1.

[0134] FIG. 3 is a schematic diagram of an example expiratory conduit, in an equilibrated state.

[0135] FIG. 4 is a schematic diagram of the expiratory conduit of FIG. 3, in a conditioned state.

[0136] FIG. 5 is a schematic diagram of another example expiratory conduit.

[0137] FIG. 6 is a perspective view of a portion of another example expiratory conduit.

[0138] FIG. 7 is a schematic cross-sectional diagram of another example expiratory conduit.

[0139] FIG. 8 is a schematic diagram of a portion of another example expiratory conduit.

[0140] FIG. 9 is a side view of another example expiratory conduit.

[0141] FIG. 10 is a schematic diagram of another example expiratory conduit, in an equilibrated state.

[0142] FIG. 11 is a schematic diagram of the expiratory conduit of FIG. 10, in a conditioned state.

[0143] FIG. 12 is a schematic diagram of another example expiratory conduit. [0144] FIG. 13 is a schematic diagram of an inspiratory conduit and an expiratory conduit in accordance with another example.

[0145] FIG. 14 is a detailed schematic diagram of portions of an inspiratory conduit, an expiratory conduit, and a plurality of retainers in accordance with another example.

[0146] FIG. 15 is a detailed schematic diagram of a pair of retainers as shown in FIG.

14.

[0147] FIG. 16 is a schematic cross-sectional diagram of the pair of retainers of FIG.

15.

[0148] FIG. 17 is a schematic cross-sectional diagram of a portion of another example expiratory conduit.

[0149] FIG. 18 is a schematic cross-sectional diagram of a portion of another example expiratory conduit.

[0150] FIG. 19 is a schematic cross-sectional diagram of a portion of another example expiratory conduit.

[0151] FIG. 20 is a detailed side view of a portion of another example expiratory conduit.

[0152] FIG. 21 is a detailed schematic cross-sectional diagram of a portion of another example expiratory conduit.

[0153] FIG. 22 is a schematic partial-cutaway diagram of a portion of another example expiratory conduit.

[0154] FIG. 23 shows detail A of FIG. 22 according to one example.

[0155] FIG. 24 shows detail B of FIG. 22 according to another example.

[0156] FIG. 25 shows detail A of FIG. 22 according to yet another example.

[0157] FIG. 26 is a schematic diagram of an example surgical insufflation system.

DETAILED DESCRIPTION

[0158] The present disclosure relates to medical gases conduits which may be used in a variety of medical gases systems including, without limitation, respiratory assistance systems, anesthesia breathing systems or surgical insufflation systems. And medical gases circuits, e.g., respiratory breathing circuits, anesthesia breathing circuits, surgical insufflation circuits.

[0159] Various example medical gases conduits are described below with particular reference to use as the expiratory conduit in a respiratory assistance system. But it will be appreciated that the example medical gases conduits may be used, or modified for use, in alternative medical gases systems, such as one or more of: as an expiratory conduit in an alternative respiratory assistance system, e.g., a respiratory assistance system configured to provide continuous positive airway pressure (CPAP) or Bubble CPAP (bCPAP) therapy; as one or more of an inspiratory conduit or an expiratory conduit in an anesthesia breathing system; or as a discharge conduit in a surgical insufflation system, for example.

[0160] Options to mitigate condensate in the inspiratory conduit and the expiratory conduit may include lowering the level of active humidification, or the use of one or more of thermal insulation, a water trap or a heater. But it has been found that each of these has at least some drawbacks.

[0161] Lowering the level of active humidification may in turn lower the absolute and/or relative humidity of the medical gases supplied to the patient. But this may not be optimal for patient comfort or recovery, e.g., when the patient's upper airway is bypassed during invasive ventilation. Nor will it necessarily address condensate or other liquids forming in, or draining into, the conduit, e.g., draining into the conduit from the patient or other components of the medical gases system.

[0162] Insulating a conduit may reduce the rate of heat loss of the medical gases as they pass along the length of the conduit. The conduit may be provided with an outer jacket of thermally insulative material or an air gap in the tube wall, for example. However, such insulation may increase one or more of the diameter, weight and cost of the conduit; impair flexibility of the conduit; or have limited effectiveness. Nor does insulation address condensate which may drain into the conduit from another component of the medical gases system.

[0163] A water trap may collect accumulated condensate and other liquids for disposal. But the position of the water trap is fixed and may not necessarily coincide with the lowest point of the conduit where condensate may accumulate, in use. A medical professional may need to periodically manipulate the conduit by elevating portions of it so that accumulated condensate drains towards, and into, the water trap. If not done carefully, this can cause some condensate to simultaneously drain towards the patient or the ventilator, for example. And condensate may become trapped within corrugations of the conduit. Moreover, the added weight of the water trap and collected condensate may increase tube drag forces. And the water trap may require periodic emptying. This may interrupt therapy to the patient, and presents an infection risk. A water trap goes some way towards addressing the problem of condensate once it is present. And it may also go some way towards addressing condensate or liquids from other components of the respiratory assistance system. But it does not address the cause of the problem, and comes with its own disadvantages.

[0164] A heater is intended to maintain or increase the temperature of the respiratory gases above their dew point. This may mitigate formation of condensate within the conduit. Potential downsides of a heater wire may include one or more of:

• The need for establishing electrical connections between the conduit and a power source, e.g., the humidifier 102;

• Added complexity in the heating and humidification algorithms;

• Relatively high temperature and absolute/relative humidity of the gases received by the ventilator;

• The need to comply with additional standards specific to heated-wire breathing tubes (e.g., International Electrotechnical Commission (IEC) 60601-1 (IEC:2005+Al:2012(E)), Section 11.2);

• Reduced shelf life; and

• Power consumption during use of a heated conduit may contribute to the overall carbon footprint, e.g., about 50% of the carbon footprint, of the heated conduit over its lifetime.

[0165] An alternative form of heater is a "water jacket" heater. Heated water or other liquid is circulated through a channel provided about the conduit. But this may have one or more of the further disadvantages of increasing one or more of the size, weight or cost of the conduit; the need for heating and pumping the water; or the risk of water leaks.

[0166] A medical gases conduit according to the present disclosure may be formed, at least in part, from a breathable material. In some examples, the medical gases conduit does not require lowering a level of active humidification. In some examples, the medical gases conduit does not include one or more, e.g., any, of thermal insulation, a water trap, or a heater.

Respiratory Assistance System

[0167] Referring to FIG. 1, a schematic diagram of an example respiratory assistance system 100 is shown. The respiratory assistance system 100 may be configured to provide non-invasive ventilation (NIV) therapy to a patient. In other examples, the respiratory assistance system 100 may be configured to provide invasive ventilation therapy to the patient.

[0168] Mechanical ventilation may vary from providing supplemental pressure and flow to assist a spontaneously breathing patient ("respiratory support") to complete control of every breath ("life sustaining"). Patients receiving mechanical ventilation may be connected to the respiratory assistance system 100 for longer than 24 hours and, depending on the patient's condition, even months at a time, or permanently.

[0169] The respiratory assistance system 100 may include a gases source 104.

[0170] In some examples, the gases source 104 may be a room-entraining ventilator. The ventilator may include a pressure generator 106, e.g., a blower or a positivedisplacement pump such as a bellows pump. The pressure generator 106 may be configured to draw ambient air 108 into the gases source 104 through an ambient air inlet 110. The pressure generator 106 may be configured to pressurize the ambient air 108 to generate a flow of respiratory gases. In some examples, the ambient air 108 may be supplemented with other gases, such as supplementary oxygen (not shown).

[0171] The gases source 104 may include a gases source controller 112. The gases source controller 112 may be configured to control operation of the pressure generator 106. In some examples, the gases source controller 112 may be configured to control or regulate one or more of the flow rate, pressure, or volume of the flow of respiratory gases.

[0172] The gases source controller 112 may include one or more processors. The gases source controller 112 may include a machine-readable medium, e.g., a non- transitory memory. The machine-readable medium may be programmed with instructions which, when executed by the one or more processors, cause the gases source 104 to operate as described herein. The gases source controller 112 may be configured to control the gases source 104 based, at least in part, on inputs received from a user interface 114. The gases source controller 112 may be configured to control the gases source 104 based, at least in part, on inputs received from one or more sensors, e.g., one or more of a flow rate sensor or a motor speed sensor. The gases source controller 112 may be configured to control the gases source 104 using closed- loop control, e.g., using a proportional-integral-derivative (PID) control algorithm.

[0173] In some examples, the gases source 104 may receive pressurized respiratory gases from a remote source. The gases source controller 112 may control the pressure of the flow of respiratory gases delivered to the patient by controlling a proportional solenoid valve, for example. [0174] In some examples, the gases source 104 may be configured to deliver a flow of respiratory gases, e.g., to an adult patient, at flow rates of up to 120 liters per minute (l/min), e.g., within the range of about 30 to 80 l/min.

[0175] In some examples, the gases source 104 may be configured to deliver a flow of respiratory gases, e.g., to a neonatal or pediatric patient, at flow rates of between about 0.5 and 60 l/min. The precise flow rate may depend on one or more of the therapy, age or the weight of the patient.

[0176] The gases source 104 may be configured to deliver the respiratory gases to the patient at pressures of up to about 6 kilopascal (kPa) (about 60 cmH₂0). Components of the respiratory assistance system 100, e.g., the conduits, may be tested and labelled for use to higher pressures, e.g., about 8 kPa (about 80 cmH₂0).

[0177] In another example, the gases source 104 may be an anesthesia machine. For anesthesia applications, the respiratory assistance system 100 may deliver a mixture of respiratory gases and an anesthetic agent to the patient, e.g., to sedate the patient and render them unconscious for surgery. The anesthetic gas mixture may be delivered to the patient at flow rates of up to about 20 l/min or, for certain "low flow" applications, up to about 10 l/min. The anesthetic gas mixture may be delivered at pressures of up to around 6 kPa. The pressure may be lower than is typical for mechanical ventilation. The anesthesia machine may include a rebreathing system which delivers gases to a patient via an inspiratory conduit and returns expired gases to the anesthesia machine via an expiratory conduit. The anesthesia machine and respiratory breathing circuit generally form a closed loop to prevent the anesthetic agent leaking to the ambient environment. Patients will usually be connected to the anesthesia machine for less than 24 hours. Patients receiving anesthetic agents may be continuously monitored by an anesthetist.

[0178] The respiratory assistance system 100 may include a humidifier supply conduit 116.

[0179] The humidifier supply conduit 116 may be configured to receive a flow of respiratory gases from a gases source outlet 118. And convey the flow of respiratory gases to downstream components of the respiratory assistance system 100, e.g., a humidifier.

[0180] The humidifier supply conduit 116 may include a tube. The tube may be flexible. The tube may be corrugated. [0181] In other examples, e.g., a respiratory assistance system 100 omitting a humidifier or including a humidifier integrated with the gases source 104, the humidifier supply conduit 116 may be omitted or replaced by internal ducting.

[0182] The respiratory assistance system 100 may include a humidifier 102.

[0183] The humidifier 102 may be configured to heat and/or humidify the flow of respiratory gases received from the gases source 104, e.g., via the humidifier supply conduit 116.

[0184] The humidifier 102 may be an active passover-type humidifier. In some examples, the humidifier 102 may be an F&P 810™, 820™, 850™ or 950™ Heated Humidifier available from Fisher 8i Paykel Healthcare Limited of Auckland, New Zealand. In other examples, the humidifier 102 may be a passive (unheated) passover-type humidifier, a heat and moisture exchanger (HME), a nebulizing humidifier, or a humidifier supplying a continuous or periodic controlled flow of a humidifying liquid to a heating element for instantaneous or near-instantaneous vaporization, for example.

[0185] The humidifier 102 may include a humidification chamber 120. The humidification chamber 120 may be configured to contain a volume of a humidification liquid, e.g., water. The humidification chamber 120 may include a chamber inlet 122 configured to receive the flow of respiratory gases. The humidification chamber 120 may include a chamber outlet 124 configured to supply the heated and humidified flow of respiratory gases to downstream components of the respiratory assistance system 100. The humidification chamber 120 may include a heat conductive body, e.g., formed from aluminum or stainless steel.

[0186] In some examples, the humidification chamber 120 may include a float valve (not shown) to maintain or replenish the volume of humidification liquid, e.g., from a sterile water bag. The humidification chamber 120 may include a water feed tube and a water spike for fluid coupling with the sterile water bag.

[0187] The humidifier 102 may include a chamber heater 126. The chamber heater 126 may include a heating element. The humidification chamber 120 may be configured to removably engage the chamber heater 126, e.g., with the heat conductive body in physical contact with the chamber heater 126. In use, heat generated by the chamber heater 126 may be conducted by the humidification chamber 120, warming the volume of humidification liquid. At least part of the volume of the humidification liquid may be vaporized, e.g., into water vapor. Respiratory gases passing through a headspace of the humidification chamber 120 may be heated and/or humidified by the volume of the humidification liquid and/or the vaporized humidification liquid. [0188] The humidifier 102 may include a humidifier controller 128. The humidifier controller 128 may be configured to control operation of the humidifier 102. The humidifier controller 128 may be configured to control a temperature of the chamber heater 126. The humidifier controller 128 may be configured to control, at least in part, one or more of a temperature or a humidity of the flow of respiratory gases.

[0189] The humidifier controller 128 may be configured to regulate, at least in part, a temperature of the flow of respiratory gases so that the respiratory gases received by the patient are at, or near, a predetermined temperature. In the case of a patient receiving non-invasive ventilation, the humidifier 102 may be configured to deliver the flow of respiratory gases to the patient at a temperature of about 31° C. In the case of a patient receiving invasive ventilation, the humidifier 102 may be configured to deliver the flow of respiratory gases to the patient at a temperature of about 37° C.

[0190] The humidifier controller 128 may be configured to regulate, at least in part, a humidity of the flow of respiratory gases so that the respiratory gases received by the patient are at, or near, a predetermined humidity. In the case of a patient receiving non-invasive ventilation, the humidifier 102 may be configured to deliver the flow of respiratory gases to the patient at a relative humidity of about 70%. In the case of a patient receiving invasive ventilation, the humidifier 102 may be configured to deliver the flow of respiratory gases to the patient at a relative humidity of about 100%.

[0191] The respiratory assistance system 100, e.g., one or more of the gases source 104, the humidifier 102, and/or the inspiratory conduit 130, may include one or more sensors. Each of the one or more sensors may be configured to sense one or more of a temperature, relative humidity, absolute humidity, flow rate, pressure, or blower speed, for example. A temperature sensor, for example, may be configured to sense a temperature of one or more of the ambient air 108, chamber heater 126, a heat conductive body of the humidification chamber 120, the humidification liquid, or the flow of respiratory gases.

[0192] The humidifier controller 128 may include one or more processors. The humidifier controller 128 may include a machine-readable medium, e.g., a non- transitory memory. The machine-readable medium may be programmed with instructions which, when executed by the one or more processors, cause the humidifier controller 128 to operate as described herein. The humidifier controller 128 may be configured to control the humidifier 102 based, at least in part, on inputs received from a user interface 132. In some examples, one or more of the predetermined temperature or predetermined humidity may be adjustable by a user. The humidifier controller 128 may be configured to control the humidifier 102 based, at least in part, on inputs received from one or more sensors. The humidifier controller 128 may be configured to control the humidifier 102 using closed-loop control, e.g., using a proportional-integral- derivative (PID) control algorithm.

[0193] In some examples, the humidifier 102 may be configured to be controlled by, or from, the gases source 104. Or vice versa. The humidifier controller 128 may be configured to control the humidifier 102 based, at least in part, on inputs received from the user interface 114 of the gases source 104. The humidifier 102 may be configured to be controlled by the gases source controller 112 of the gases source 104. The gases source 104, e.g., the gases source controller 112, and the humidifier 102, e.g., the humidifier controller 128, may be communicatively coupled by any suitable wired or wireless communications link 134.

[0194] The gases source 104 and the humidifier 102 may be separate devices, as shown in FIG. 1. In other examples, the gases source 104 and humidifier 102 may be integrated, e.g., in a single housing. In such examples, the humidifier supply conduit 116 may be replaced by internal ducting. The functions of the gases source controller 112 and humidifier controller 128 may be performed by a single controller. The user interface 114 and the user interface 132 may be replaced by a single user interface.

[0195] The respiratory assistance system 100 may include an inspiratory conduit 130.

[0196] The inspiratory conduit 130 may be configured to receive the flow of respiratory gases from the humidifier 102, e.g., the chamber outlet 124. Or, in examples omitting a humidifier, directly from the gases source 104. The inspiratory conduit 130 may be configured to convey the flow of respiratory gases to downstream components of the respiratory assistance system 100, e.g., a Y-piece and/or patient interface.

[0197] In some examples, the inspiratory conduit 130 may have a length of about 1.0 meters (m) to about 2.5 m. In some examples, the inspiratory conduit 130 may have a length of about 1.5 m to 1.8 m, e.g., about 1.6 m or 1.8 m. In other examples, e.g., for anesthesia applications, the inspiratory conduit 130 may have a length of about 2.2 m to 2.6 m, e.g., about 2.4 m.

[0198] The inspiratory conduit 130 may include an elongate tube. The elongate tube may be flexible. A pair of connectors may be provided at respective ends of the elongate tube for connecting the inspiratory conduit 130 with other components of the respiratory assistance system 100.

[0199] The elongate tube may be corrugated. In some examples, e.g., for an adult patient, the corrugated inspiratory conduit 130 may have a maximum outside diameter (that is, the diameter of the inspiratory conduit 130 when measured to outer surfaces at an outer peak of a corrugation) of about 20 millimeters (mm) to 30 mm, or about 23 mm to 25 mm, e.g., about 24 mm. In other examples, e.g., for a neonatal or pediatric patient, the maximum outside diameter may be about 10 mm to 20 mm, or about 14 mm to 16 mm, e.g., about 15 mm. The inspiratory conduit 130 may have a corrugated inner surface. In other examples, the inspiratory conduit 130 may have a substantially smooth (e.g., uncorrugated) inner surface.

[0200] In other examples, the elongate tube may be helical or have a helical outer profile. The helical elongate tube may be formed from one or more helically-wound components, e.g., two components wound in a double-helix configuration. A first spirally-wound component may be an elongate hollow body, and a second spirally-wound component may be an elongate structural component. Heating and/or sensing wires may be embedded in the elongate structural component. Further design and manufacturing details of such conduits are disclosed in United States Patent Publication Nos. 2015/0306333, 2017/0100556, 2019/0076620 and 2022/0355059, the entire contents of which are incorporated herein by reference.

[0201] The inspiratory conduit 130 may include a heater wire 136 (illustrated in part, for clarity). The heater wire 136 may be wrapped around an outside of the elongate tube, embedded within the elongate tube or located within the lumen of the elongate tube, for example. The heater wire 136 may be powered by the humidifier 102. The heater wire 136 may be controlled by the humidifier controller 128. The heater wire 136 may be operated to mitigate heat loss of the respiratory gases as they pass along the length of the inspiratory conduit 130. In some examples, the heater wire 136 may maintain, or in some cases increase, the temperature of the respiratory gases as they pass along the length of the inspiratory conduit 130.

[0202] In some examples, sensor probes 138 may be removably inserted in sensor probe ports at one or more of the humidifier end or the patient end of the inspiratory conduit 130. The sensor probes 138 may include one or more of a temperature sensor, a humidity sensor, or a flow sensor, for example. Sensor leads 140 may connect the sensor probes 138 to the humidifier 102. Signals from the sensor probes 138 may be used as inputs in the control of one or more of the pressure generator 106 or the chamber heater 126 or heater wire 136. In some examples, the sensors may be integrated with, e.g., embedded in, the inspiratory conduit 130. The sensor leads 140 may be integrated with, e.g., embedded in, the elongate tube as sensor wires. Or the sensors may be integrated in the humidifier 102.

[0203] In some examples, the inspiratory conduit 130 does not include, at or near the patient end of the inspiratory conduit 130, either sensor probe ports or an integrated sensor, e.g., temperature sensor. In some examples, the inspiratory conduit 130 does not include either sensor probe ports or an integrated sensor at all. In some examples, the humidifier 102 and/or the respiratory assistance system 100 do not include sensor leads 140.

[0204] The connectors may be configured to establish and maintain pneumatic connections with the chamber outlet 124 of the humidification chamber 120 or an inlet of a Y-piece, respectively. In some examples, e.g., for an adult patient, the connectors may each be an adapter with a 22 mm conical connector. The connectors may have a 1 :40 taper complying with the International Organization for Standardization (ISO) 5356-1 : 2015 (Anaesthetic and respiratory equipment — Conical connectors — Part 1: Cones and sockets) standard. In other examples, e.g., for a neonatal or pediatric patient, the connectors may be any of a 15 mm tapered male conical connector, a 15 mm tapered female conical connector, a 12 mm tapered male conical connector, a 12 mm tapered female conical connector, or a combination of any two such connectors.

[0205] In some examples, the connector at the humidifier end of the inspiratory conduit 130 may have a socket for receiving a sensor probe 138. In some examples, the connector at the humidifier end of the inspiratory conduit 130 may have a socket for establishing an electrical connection between the humidifier 102 and the heater wire 136. In other examples, the humidifier 102 and the connector at the humidifier end of the inspiratory conduit 130 may have corresponding integrated electrical contacts whereby both pneumatic and electrical connections may be established upon physically connecting the inspiratory conduit 130 to the humidifier 102.

[0206] The respiratory assistance system 100 may have a Y-piece 142.

[0207] The Y-piece 142 may include an inspiratory inlet. The inspiratory inlet may be configured to couple with the inspiratory conduit 130. The Y-piece 142 may be configured to receive the flow of respiratory gases from the inspiratory conduit 130, in use.

[0208] The Y-piece 142 may include a respiratory inlet/outlet. The respiratory inlet/outlet may be configured to couple with one or more of the patient interface 144 or a patient conduit (not shown), e.g., a catheter mount, intermediate the respiratory inlet/outlet and the patient interface 144. The respiratory inlet/outlet may be configured to receive the flow of respiratory gases from the inspiratory inlet. The respiratory inlet/outlet may be configured to receive respiratory gases expired by the patient.

[0209] The Y-piece 142 may include an expiratory outlet. The expiratory outlet may be configured to couple with an expiratory conduit. The expiratory outlet may be configured to receive the respiratory gases expired by the patient from the respiratory inlet/outlet. The expiratory outlet may be configured to receive excess respiratory gases from the inspiratory inlet, e.g., during the patient's expiratory phase. The expiratory outlet may be configured to supply one or more of the respiratory gases expired by the patient or the excess respiratory gases to the expiratory conduit.

[0210] In some examples, the inspiratory inlet and the expiratory outlet may converge towards the respiratory inlet/outlet. In other examples, the inspiratory inlet and the expiratory outlet, at least in part, may be substantially parallel to each other.

[0211] The respiratory assistance system 100 may include a patient interface 144.

[0212] The patient interface 144 may be any suitable non-invasive or invasive patient interface. In some examples, the patient interface 144 may be a sealing patient interface. In other examples, e.g., respiratory assistance systems configured to deliver high flow therapy (HFT), the patient interface 144 may be a non-sealing patient interface.

[0213] Examples of non-invasive patient interfaces include:

• total-face masks, e.g., configured to seal around the patient's eyes, nose and mouth;

• full-face masks, e.g., configured to seal around the patient's nose and mouth;

• nasal masks, e.g., configured to seal around the patient's nose;

• compact nasal masks, e.g., configured to seal with an underside of the patient's nose, around the nares;

• nasal pillows interfaces, e.g., configured to seal with each of the patient's nares;

• sealing nasal cannulae, e.g., configured to seal inside each of the patient's nares;

• unsealed nasal cannulae, e.g., configured to extend into the patient's nares without occluding the nasal passages;

• oral masks, e.g., configured to seal around the patient's mouth; and

• combinations of the above, e.g., a combination compact nasal mask and oral mask, or a combination full-face mask and unsealed nasal cannulae.

[0214] Examples of invasive patient interfaces include:

• endotracheal tubes; and

• tracheostomy tubes.

[0215] In the illustrated example, the patient interface 144 is a nasal mask.

[0216] In some examples, the respiratory assistance system 100 may be configured, or configurable, to deliver the flow of respiratory gases to the patient's lungs at one or more of a temperature of about 37° Celsius or a relative humidity of about 100%.

[0217] The respiratory assistance system 100 may include an expiratory conduit 146. [0218] The expiratory conduit 146 may be configured to receive the flow of respiratory gases, e.g., the respiratory gases expired by the patient and the excess respiratory gases, from the Y-piece 142. The expiratory conduit 146 may be configured to convey the flow of respiratory gases to downstream components of the respiratory assistance system 100. In some examples, this may be a gases return inlet 148 of the gases source 104, as shown in FIG. 1.

[0219] In other examples, e.g., in a respiratory assistance system configured to provide bCPAP therapy, the expiratory conduit 146 may be configured to convey the flow of respiratory gases to a pressure regulator, e.g., a bubbler. An inlet probe may be configured to be submerged in a reservoir of water within the bubbler. The depth of the inlet probe may determine the pressure of the flow of respiratory gases.

[0220] The expiratory conduit 146 may have a length of between about 0.8 m and 2.5 m, in an equilibrated state. In some examples, the expiratory conduit 146 may have a length of between about 0.8 m and 1.4 m, or between about 1.0 m and 1.4 m, e.g., about 1.2 m. In some examples, the expiratory conduit 146 may have a length of between about 1.2 m and 2.0 m, or between about 1.4 m and 1.8 m, e.g., about 1.6 m. In some examples, e.g., for anesthesia applications, the expiratory conduit 146 may have a length of between about 2.3 m and 2.5 m, e.g., about 2.4 m.

[0221] The expiratory conduit 146 may include an elongate tube. The elongate tube may be flexible. A pair of connectors may be provided at respective ends of the elongate tube for connecting the expiratory conduit 146 with other components of the respiratory assistance system 100.

[0222] The elongate tube may be corrugated. In some examples, e.g., for an adult patient, the corrugated expiratory conduit 146 may have a maximum outside diameter (that is, the diameter of the inspiratory expiratory conduit 146 when measured to outer surfaces at an outer peak of a corrugation) of about 20 millimeters (mm) to 30 mm, or about 23 mm to 25 mm, e.g., about 24 mm. In other examples, e.g., for a neonatal or pediatric patient, the maximum outside diameter may be about 10 mm to 20 mm, or about 14 mm to 16 mm, e.g., about 15 mm. The expiratory conduit 146 may have a corrugated inner surface. In other examples, the expiratory conduit 146 may have a substantially smooth (e.g., uncorrugated) inner surface.

[0223] In other examples, the elongate tube may be formed by one or more helically- wound components as described above with respect to the inspiratory conduit 130.

[0224] The connectors may be configured to establish and maintain pneumatic connections with one or more of the Y-piece 142, the gases source 104, or an optional filter (not shown) intermediate the expiratory conduit 146 and the gases source 104. One or more of the pair of connectors may include a conical connector as described above with respect to the inspiratory conduit 130.

[0225] The flow of respiratory gases in the respiratory assistance system 100 may be heated and/or humidified by one or more of the humidifier 102, the heater wire 136, or the patient's upper airway (e.g., for non-invasive ventilation). And the respiratory gases conveyed by the expiratory conduit 146 may have a relatively high temperature and humidity. In some examples, the respiratory gases may have a temperature of at least 5 °C, or at least 10 °C, above a temperature of the ambient air 108. In some examples, the respiratory gases may have a relative humidity of up to 100% (i.e., saturation).

[0226] In some examples, the expiratory conduit 146 does not include a heater, e.g., a heater wire. Omission of a heater wire may have one or more of the advantages of:

• simplifying manufacture;

• reducing manufacturing and materials costs;

• improving usability by avoiding the need for establishing an electrical connection between the expiratory conduit 146 and a power source such as the humidifier 102 or the gases source 104;

• avoiding the need for heater wire control algorithms;

• improving safety;

• reducing surface temperatures of the expiratory conduit 146;

• improving pneumatic performance;

• reducing regulatory burdens (e.g., International Electrotechnical Commission (IEC) 60601-1 (IEC: 2005+Al :2012(E)), Section 11.2);

• reducing the temperature of the respiratory gases received by the gases source 104, e.g., gases return inlet 148;

• improved reliability;

• longer shelf life, e.g., where electrical insulation is a limiting factor;

• enabling longer duration of use, e.g., where electrical insulation is a limiting factor; or

• reducing power consumption, and thus the carbon footprint, of the expiratory conduit 146.

[0227] In some examples, the humidifier 102 is not configured to supply power to the expiratory conduit 146, e.g., a heater wire of the expiratory conduit 146. In some examples, the humidifier 102 is not configured to control power delivered to the expiratory conduit 146, e.g., a heater wire of the expiratory conduit 146.

[0228] In other examples, the expiratory conduit 146 may include a heater wire. The heater wire may be similar to the heater wire 136 as described above with respect to the inspiratory conduit 130. The expiratory conduit 146 may be powered by the humidifier 102. Power delivered to the expiratory conduit 146 may be controlled by the humidifier controller 128.

[0229] In some examples, the expiratory conduit 146 does not include, or provide for use of, a water trap. Omission of a water trap may provide one or more of the advantages of:

• simplifying manufacture;

• reducing manufacturing and materials costs;

• improving usability by avoiding the need to empty the water trap;

• reducing infection risk;

• reducing weight of the expiratory conduit 146;

• reducing tube drag forces; or

• reducing interruptions to therapy.

[0230] In some examples, one or more of the inspiratory conduit 130 or the expiratory conduit 146 may have an identification element. The identification element may be a resistor, a capacitor, or an integrated circuit (IC), for example. The identification element may enable one or more of the humidifier 102 or the gases source 104 to identify the conduit. In some examples, one or more of the humidifier 102 or the gases source 104 may be configured to automatically adjust one or more therapy parameters based on identification of one or more of the inspiratory conduit 130 or the expiratory conduit 146. In some examples, the identification element may enable identification of one or more of the manufacture, type (e.g., model), or serial number of the conduit. In some examples, the identification element may be configured to communicate with the humidifier 102 or the gases source 104 via a wired connection. In other examples, the identification element may be configured to communicate wirelessly, e.g., using radio frequency identification (RFID).

[0231] The respiratory assistance systems 100 may include a filter. The filter may be provided between the expiratory conduit 146 and the gases source 104, e.g., the gases return inlet 148. In some examples, a filter may additionally, or alternatively, be provided within the gases source 104.

[0232] The respiratory assistance system 100 may include a conduit hanger.

[0233] The conduit hanger may be configured to receive and retain one or more of the inspiratory conduit 130 or the expiratory conduit 146. The conduit hanger may be configured to be secured in position near the patient. Use of the conduit hanger may mitigate a drag force acting upon one or more of the patient conduit, catheter mount, or patient interface 144. [0234] The humidifier supply conduit 116, humidification chamber 120, inspiratory conduit 130, Y-piece 142, and expiratory conduit 146 together form a respiratory breathing circuit. More specifically, a dual-limb respiratory breathing circuit 150.

[0235] An inspiratory branch 152 of the respiratory breathing circuit 150 extends from the gases source 104 to the Y-piece 142. In some examples, the inspiratory branch 152 of the respiratory breathing circuit 150 may be formed by the combination of the humidifier supply conduit 116, the humidification chamber 120 and the inspiratory conduit 130.

[0236] An expiratory branch 154 of the respiratory breathing circuit 150 extends from the Y-piece 142 to the gases return inlet 148 of the gases source 104. In some examples, the expiratory branch 154 may be formed by the expiratory conduit 146. In other examples, the expiratory branch 154 may be formed by the combination of the expiratory conduit 146 and the filter. In some examples, the expiratory conduit 146 may form upwards of about 80%, upwards of about 90%, upwards of about 95%, or about 100% of the length of the expiratory branch 154.

[0237] With the possible exception of portions of the expiratory conduit 146 being inadvertently or temporarily covered by a patient's limbs, clothing, bedding or the like, in use, the entirety of the expiratory branch 154 will generally be exposed to the ambient air 108 of the surrounding environment, e.g., a hospital room. Flow paths internal to the gases source 104 are not regarded as part of the expiratory branch 154.

[0238] One or more components of the respiratory breathing circuit may be packaged together and sold as a respiratory breathing circuit kit. The respiratory breathing circuit kit may further include one or more other components of the respiratory assistance system 100. In some examples, the respiratory breathing circuit kit may include any one or more of the humidifier supply conduit 116, humidification chamber 120, inspiratory conduit 130, Y-piece 142, catheter mount, patient interface, conduit hanger, expiratory conduit 146, filter. In one example, the respiratory breathing circuit kit may include the humidifier supply conduit 116, humidification chamber 120, inspiratory conduit 130, Y-piece 142, and expiratory conduit 146. And optionally the filter.

[0239] In some examples, the respiratory breathing circuit kit may be at least partially pre-assembled. The humidifier supply conduit 116 may be connected with the humidification chamber 120, e.g., the chamber inlet 122. The inspiratory conduit 130 may be connected with the humidification chamber 120, e.g., the chamber outlet 124. One or more of the inspiratory conduit 130 or the expiratory conduit 146 may be connected with the Y-piece 142. Preassembly of the respiratory breathing circuit kit may provide one or more of the benefits of quicker setup of the respiratory assistance system 100, or reducing the risk of misconnections, e.g., transposition of the inspiratory conduit 130 and expiratory conduit 146.

[0240] In some examples, the components of the respiratory breathing circuit kit may be packaged together, e.g., in a sealed plastic bag. A number of respiratory breathing circuit kits, e.g., 10 respiratory breathing circuit kits, may be packaged together, e.g., in a cardboard box.

[0241] FIG. 2 illustrates in further detail an example humidifier 102 which may be used in the respiratory assistance system 100. Also shown, in part, are the humidifier supply conduit 116 and the inspiratory conduit 130.

[0242] In some examples, the humidifier 102 may be an F&P 950™ respiratory humidifier available from Fisher & Paykel Healthcare Limited of Auckland, New Zealand.

[0243] The humidifier 102 may include a heater base 202 and a humidification chamber 120.

[0244] The humidifier 102, e.g., heater base 202, may include a housing 204. The housing 204 may be configured to house, at least in part, one or more components of the humidifier 102, e.g., one or more of the humidifier controller 128, the user interface 132, the chamber heater, a cartridge 206, one or more sensors, or a power supply.

[0245] The heater base 202 may include a chamber heater 126. The heater base 202 may be configured to heat a volume of water contained within the humidification chamber 120, in use. The chamber heater 126 may include a heater plate. The chamber heater 126 may include a heating element. The chamber heater 126 may include a ceramic heater.

[0246] In some examples, the chamber heater 126 may be resiliently mounted to the heater base 202. The chamber heater 126 may be sprung. The sprung chamber heater 126 may provide a force against the humidification chamber 120, in use, e.g., an upwards force against a bottom of the humidification chamber 120.

[0247] The humidifier 102, e.g., heater base 202, may include the user interface 132. The user interface 132 may be configured to receive inputs from a user, e.g., a medical professional and/or the patient. The user interface 132 may be configured to display information to the user.

[0248] The user interface 132 may include one or more buttons 208. The one or more button 208 may be push-buttons or may be touch-sensitive buttons. In some examples, the user interface 132 may include a power button configured to be operated by the user, e.g., to power the humidifier 102 on or off, or to put the humidifier 102 into a standby mode. In some examples, the one or more of the buttons 208 may be supplemented or replaced by one or more switches, dials, or sliders.

[0249] The user interface 132 may include a display 210. The display 210 may be a liquid crystal display (LCD) or organic light-emitting diode (OLED) display. The display 210 may be configured to display information to the user. In some examples, the display 210 may be a touch-sensitive display. The touch-sensitive display may be configured to receive inputs from the user.

[0250] The user interface 132 may include one or more indicator lights 212. The one or more indicator lights 212 may be configured to visually communicate information to the user and/or visually draw attention to the humidifier 102. An indicator light 212 may be a light emitting diode (LED), for example. In some examples, the indicator light 212 may be illuminated to signal an alarm condition, in use. In some examples, the indicator light 212 may be multicolored, e.g., selectively illuminated in two or more different colors such as two or more of green, amber or red. In some examples, the indicator light 212 may be illuminated intermittently, e.g., flashed on and off in a pattern. A severity of the alarm condition may be indicated by one or more of the color, intermittent illumination, pattern of intermittent illumination, or brightness of the one or more indicator lights 212, for example. Further information on the alarm condition may be displayed, or displayable, on the display 210.

[0251] The user interface 132 may include an audio device. The audio device may be configured to audibly communicate information to the user and/or audibly draw attention to the humidifier 102. The audio device may be a buzzer or a speaker, for example. In some examples, the audio device may sound an audible alarm to signal an alarm condition. In some examples, the audio device may be operable to generate two or more different tones or sounds. In some examples, the audible alarm may be sounded intermittently. A severity of the alarm may be indicated by one or more of a tone or sound, frequency, or volume of the audible alarm, for example. Further information on the alarm condition may be displayed, or displayable, on the display 210.

[0252] The humidifier 102, e.g., the heater base 202, may include a cartridge 206. The cartridge 206 may be removably attached with the housing 204 of the heater base 202.

[0253] The cartridge 206 may be a sub-housing. The cartridge 206 may include electronics. The electronics may include one or more sensors. The sensors of the cartridge 206 may be configured to sense one or more properties of the flow of respiratory gases through the humidification chamber 120, in use. For example, one or more of the temperature, humidity, or flow rate of the flow of respiratory gases. The sensors may be provided on one or more sensor probes protruding from the cartridge 206. The sensor probes may protrude through an aperture in the humidification chamber 120, e.g., in one or more of the chamber inlet or chamber outlet, in use. The aperture may be sealed or closed by an elastomeric seal. The elastomeric seal may be elastically deformed by a sensor probe when the humidification chamber 120 is received by the heater base 202.

[0254] The electronics of the cartridge 206 may include an electrical connector configured to may make an electrical connection with the heater base 202 for communication (e.g., serial communication) with, or within, the humidifier controller.

[0255] The electronics of the cartridge 206 may include an electrical connector configured to make an electrical connection with the inspiratory conduit 130.

[0256] The electronics of the cartridge 206 may include one or more processors configured to communicate with one or more of the sensor(s) and the humidifier controller.

[0257] A heater base 202 may be retrofitted with a replacement cartridge 206. The replacement cartridge 206 which may be configured to provide new or improved functionality to the humidifier 102.

[0258] The humidifier 102, e.g., the heater base 202 and/or the cartridge 206, may include the humidifier controller 128 as described above with reference to FIG. 1.

[0259] In some examples, the humidifier 102, e.g., cartridge 206 may have a socket or integrated cable configured for optional connection to an expiratory conduit 146. The humidifier 102 may be configured to supply power to the expiratory conduit 146. The humidifier controller 128 may be configured to control power supplied to an optional heater wire of the expiratory conduit 146.

[0260] The humidification chamber 120 may be configured to be removably received by the heater base 202. And secured in thermal contact with the chamber heater 126.

[0261] The humidification chamber 120 may include a hollow body and a heat conductive body together configured to define a chamber to contain a volume of water. The humidification chamber 120 may include a sealing element configured to form a seal between the hollow body and the heat conductive body.

[0262] The hollow body may be dome-shaped. With an opening configured to be closed by the heat conductive body. [0263] The hollow body may include the chamber inlet 122 and the chamber outlet 124, e.g., through an upper surface of the hollow body. In some examples, the chamber inlet 122 may be arranged vertically. The humidification chamber 120, e.g., the chamber inlet 122, may include a baffle to redirect the incoming flow of respiratory gases. The baffle may impede the incoming flow of respiratory gases from being directed straight at the surface of the water, which may otherwise cause ripples or splashing. The baffle may increase a dwell time within the humidification chamber 120, e.g., by impeding the flow of respiratory gases flowing directly from the chamber inlet 122 to the chamber outlet 124. In some examples, the chamber outlet 124 may be arranged horizontally. The chamber outlet may include an elbow, e.g., redirecting the flow of respiratory gases from a vertical direction to a horizontal direction, in use.

[0264] The hollow body may be transparent. The hollow body may be formed from a relatively rigid plastics material such as polycarbonate or acrylonitrile butadiene styrene (ABS).

[0265] The heat conductive body may be configured to engage the chamber heater 126 of the heater base 202 when the humidification chamber 120 is received by the heater base 202. And conduct heat from the chamber heater 126. The heat conductive body may be formed from aluminum or stainless steel, for example. In some examples, the heat conductive body may be permanently joined with the hollow body, e.g., by crimping. The humidification chamber 120 may be disposable. In other examples, the hollow body may be removably joined with the heat conductive body, e.g., by a friction fit. The humidification chamber 120 may be autoclavable. The humidification chamber 120 may reusable.

[0266] In some examples, the humidification chamber 120 may be configured to be replenished with water during use, e.g., via a gravity feed or a pump. The humidification chamber 120 may include a water tube and a spike. The spike may be configured puncture a water source, e.g., a sterile water bag, to fluidly couple the water source with the interior of the humidification chamber 120 via the water tube. The humidification chamber 120 may include a float valve. The float valve may be configured to automatically control the flow of water to maintain the volume of water within the humidification chamber 120 above a predetermined level, and/or within a predetermined range.

[0267] The humidifier supply conduit 116 may include a connector 214. The connector 214 may be configured to establish a pneumatic connection with the humidification chamber 120, e.g., chamber inlet 122. The connector 214 may include an elbow, e.g., at angle of between about 90 ⁰ and 175 °, or between about 100 ⁰ and 145 °, or about 120 °. [0268] The inspiratory conduit 130 may include a connector 216, e.g., an electropneumatic connector. The connector 216 may be configured to establish a pneumatic connection with the humidification chamber 120, e.g., chamber outlet 124. The connector 216 may be configured to establish an electrical connection with the heater base 202, e.g., the cartridge 206.

[0269] The connector 216 may make a releasable and lockable connection with one or more of the humidification chamber 120 or the heater base 202, e.g., the cartridge 206. The connector 216 may be configured to provide one or more of tactile or audible feedback when the releasable and lockable connection is made. The connector 216 may include a release button 218. The release button 218 may be actuated to facilitate disconnection of the inspiratory conduit 130 from the humidifier 102.

[0270] In some examples, the connector 216 may be configured so that it can be physically and pneumatically coupled with the humidification chamber 120, e.g., chamber outlet, before the humidification chamber 120 is installed on the heater base 202. And to make an electrical connection with the heater base 202, e.g., cartridge 206, as the humidification chamber 120 is installed on the heater base 202 in a sliding motion, e.g., in a horizontal direction.

[0271] In some examples, the connector 216 may be configured so that it can be pneumatically coupled with the humidification chamber 120 when the humidification chamber 120 is already installed on the heater base 202. And electrically connected with the heater base 202, e.g., cartridge 206, substantially simultaneously, e.g., in a single action. This may allow the humidification chamber 120 and the inspiratory conduit 130 to be supplied pre-assembled and ready for use as part of a respiratory breathing circuit kit, for example.

[0272] The connector 216 may include electrical terminals coupled with a pair of sensor wires of the inspiratory conduit 130. The sensor wires may be embedded within the tube wall of the inspiratory conduit 130. The sensor wires may be configured to form a sensing circuit with a sensor, e.g., at a distal end of the inspiratory conduit 130, and the heater base 202, e.g., cartridge 206.

[0273] The connector 216 may include electrical terminals coupled with a pair of heater wires 136 of the inspiratory conduit 130. The heater wires 136 may be electrically coupled, e.g., at a distal end of the inspiratory conduit 130. The heater wires 136 may be configured to form a heating circuit with the heater base 202, e.g., cartridge 206.

[0274] The connector 216 may include electrical terminals electrically coupled with an identification element, e.g., a resistor. The identification element may be embedded within the connector 216. The humidifier 102, e.g., humidifier controller 128 or cartridge 206, may be configured to identify the inspiratory conduit 130, e.g., a type of the inspiratory conduit, coupled with the humidifier 102 in use. For example, by determining a resistance of the resistor. A resistance of, e.g., about 100 Ohms ( ) may indicate that a first type of inspiratory conduit 130, e.g., an adult conduit, is connected to the humidifier 102. A resistance of, e.g., about 200 may indicate that a second type of inspiratory conduit 130, e.g., a neonatal conduit, is connected to the humidifier 102. The humidifier controller may be configured to adjust control accordingly. For example, an adult conduit may include a single heating zone, whereas a neonatal conduit may include two or more heating zones. In some examples, two heating zones may be selectively operated based on the polarity of a potential difference applied to a pair of electrical terminals.

[0275] The electrical terminals of the connector 216 may be configured to make an electrical connection with corresponding terminals of the humidifier 102, e.g., cartridge 206.

[0276] Various example medical gases conduits and variants are described in detail below with particular reference to use as the expiratory conduit 146 of the respiratory assistance system 100. But the example expiratory conduits 146 may alternatively be used, or modified for use, in alternative medical gases systems.

[0277] Aside from the differences described below, or otherwise apparent from the accompanying drawings, the following example expiratory conduits and variants may be similar to the expiratory conduit 146 of the example respiratory assistance system.

Breathable material

[0278] In some examples, a medical gases conduit may be formed, at least in part, from a breathable material (defined in the Glossary below). Breathable materials and medical gases conduits including such materials are disclosed in International Patent Application No. PCT/NZ2023/050040 entitled "Medical Gases Conduit", published as International Publication No. WO 2023/195865 Al, the entire content of which is incorporated herein by reference.

[0279] The breathable material may be permeable to water molecules. Yet relatively impermeable to liquid water and respiratory gases. Under a scanning electron microscope (SEM) at a magnification of 150x or 2500x, a breathable material, e.g., an unfoamed breathable material, may be devoid of any channels or pores. A foamed breathable material may have a number of closed-cell voids, but no open channels or pores extending from one major surface of the breathable material to the other. Water molecules may be absorbed by the breathable material, diffused through the breathable material, and desorbed to ambient air. This is known as the solution-diffusion mechanism. The water molecules may pass through the breathable material according to a gradient, moving from the higher humidity side, e.g., within the lumen of the medical gases conduit, to the lower humidity side, e.g., exposed to ambient air.

[0280] By way of contrast, a porous material, e.g., a porous membrane such as an expanded polytetrafluoroethylene (ePTFE) fabric (e.g., Gore-Tex® fabric available from W. L. Gore & Associates), has open channels extending from one major surface to the other. Porous materials are permeable to water molecules by the pore-flow mechanism. Water passes from one side of the porous material to the other via the open channels. The open channels may also allow passage of pathogens.

[0281] In some examples, the breathable material may be a block copolymer. The block copolymer may include hard segments of polybutylene terephthalate. The block copolymer may include soft segments of an ether type macro glycol. In some examples, one or more additives may be added to the breathable material. The additives may include one or more of a foaming agent, colorant, ultraviolet (UV) stabilizer, UV absorber, or processing aid, for example. In some examples, the additive(s) may form up to about 10%, up to about 8%, up to about 5%, or up to about 3%, e.g., about 3% or 1.5%, of the breathable material of the elongate tube by one or more of mass, weight or volume.

[0282] Use of a breathable material in an expiratory conduit may reduce the absolute and relative humidity of the flow of respiratory gases within the lumen as they pass along the length of the expiratory conduit. This in turn may lower the dew point of the flow of respiratory gases.

[0283] Examples of medical gases conduits including a breathable material are the expiratory conduits of various respiratory breathing circuits with EVAQUA™ technology available from Fisher 8i Paykel Healthcare, such as the RT280™ and RT340™ Adult Breathing Circuits with EVAQUA™ Technology. These expiratory conduits include a heater wire. But they do not include a water trap. They have proven effective in reducing the formation of condensate within the conduit. But it has been found that in at least some conditions, condensate or other liquids, e.g., from other sources such as the catheter mount, patient, nebulizer or the like, may still accumulate in the expiratory conduit with prolonged use. Details of such expiratory conduits are disclosed in United States Patent Nos. 6,769,431 and 10,532,177, both assigned to Fisher 8i Paykel Healthcare Limited.

[0284] It has been found that breathable materials with higher permeability to water molecules may be more effective in mitigating accumulation of condensate or other liquids within the expiratory conduit. Therefore, an expiratory conduit formed from a relatively more breathable material may require fewer or less frequent interventions to remove condensate. And, in at least some examples, breathable materials with higher permeability to water molecules may permit omission of the heater wire from the expiratory conduit.

[0285] But such breathable materials have been found to absorb a relatively large mass of water molecules in use, significantly altering the mechanical properties of the expiratory conduit. For example, the breathable material may expand, become less rigid, and/or become less resilient. This may present challenges in meeting certain standards or other design requirements, e.g., throughout a range of different conditions. For example, conduits in a respiratory assistance system may be required to comply with certain minimum requirements specified by formal standards such as the ISO 5367:2014(E) (Anaesthetic and respiratory equipment — Breathing sets and connectors) standard. This standard specifies basic requirements for: i. materials,

II. length, ill. connections, iv. leakage, v. resistance to flow, and vi. compliance.

[0286] Due to these changes in mechanical properties, an expiratory conduit which complies with certain standards or other design requirements prior to use may not necessarily do so during or immediately after use in a respiratory assistance system.

[0287] Because the state of the medical gases conduit may vary in use, throughout the detailed description and claims the terms "dry state," "equilibrated state," "conditioned state" and "saturated state" refer to various different states, or ranges of states, of the expiratory conduit or elongate tube. These states are each defined in the Glossary, below.

[0288] FIG. 3 illustrates, in schematic form (e.g., not to scale), an expiratory conduit 146 according to a first example. The expiratory conduit 146 is shown in an equilibrated state, e.g., prior to use.

[0289] The expiratory conduit 146 may include a pair of connectors 302, 304. The first connector 302 may be configured to connect with the Y-piece 142, e.g., the expiratory outlet of the Y-piece 142. The second connector 304 may be configured to connect with one or more of a filter or the gases source 104, e.g., the gases return inlet 148. In some examples, the connectors 302, 304 may be identical. In other examples, the connectors 302, 304 may differ in one or more of dimensions, materials, markings, or the like.

[0290] The expiratory conduit 146 may include an elongate tube 306. The elongate tube 306 may define a lumen for the passage of the flow of respiratory gases, e.g., between the connectors 302, 304.

[0291] The elongate tube 306 may be formed, at least in part, from a breathable material. The breathable material may extend the full length of the elongate tube 306. And the breathable material may extend a substantial entirety of the expiratory branch 154 of the respiratory assistance system 100, e.g., excluding only the connectors 302, 304 and optionally a filter intermediate the expiratory conduit 146 and the gases source 104, e.g., gases return inlet 148.

[0292] In immersion testing (described in the Glossary, below), sample specimens of the elongate tube 306 may absorb more than about 33%, between about 33% and 200%, between about 100% and 160%, between about 120% and 140%, or between about 130% and 135%, e.g., about 133% of its own mass in water molecules.

[0293] In some examples, sample specimens of the elongate tube 306 expand by between about 20% and 70% in one or more of a radial direction, e.g., a maximum outside diameter, a longitudinal direction, i.e., length, or a wall thickness of the elongate tube. In some examples, sample specimens of the elongate tube 306 may expand by between about 20% and 70%, between about 25% and 50%, or between about 30% and 50%, in one or more of the radial direction, the longitudinal direction, or the wall thickness. In one example, sample specimens of the elongate tube 306 were found to expand in the radial direction by about 42%, the longitudinal direction by about 37% and wall thickness by about 34%. In another example, sample specimens of the elongate tube 306 were found to expand in each of the radial direction, the longitudinal direction and the wall thickness by about 32% each.

[0294] In some examples, a wall thickness of the elongate tube 306, in a dry state, may be between about 0.5 mm and 0.9 mm, between about 0.6 mm and 0.8 mm, between about 0.65 mm and 0.75 mm, between about 0.68 mm and 0.72 mm, or between about 0.69 mm and 0.71mm, e.g., about 0.70 mm. In a saturated state, the same elongate tube 306 may have a wall thickness of between about 0.7 mm and 1.1 mm, between about 0.8 mm and 1.0 mm, between about 0.85 mm and 0.95 mm, between about 0.90 mm and 0.94 mm, or between about 0.91 mm and 0.93 mm, e.g., about 0.92 mm.

[0295] In some examples, a maximum outer diameter of the elongate tube, in a dry state, may be between about 20 mm and 26 mm, between about 21 mm and 25 mm, or between about 22 mm and 24 mm, e.g., about 23 mm. In a saturated state, the same elongate tube 306 may have a maximum outer diameter of between about 25 mm and 35 mm, between about 28 mm and 32 mm, or between about 29 mm and 31 mm, e.g., about 30 mm.

[0296] In some examples, the expiratory conduit 146 may include one or more intermediate connectors, e.g., a mid-point connector at or near a mid-point between the connectors 302, 304. In some examples, the expiratory conduit 146 may include two or more elongate tubes 306. The two or more elongate tubes 306 may be identical, or may differ. At least one of the two or more elongate tubes 306 may be formed, at least in part, from a breathable material. The intermediate connector may connect, e.g., permanently connect, two elongate tubes together.

[0297] The expiratory conduit 146 of FIG. 3 is shown in an equilibrated state, e.g., prior to use. In the equilibrated state, a diameter of the elongate tube 306 may be substantially uniform along a length of the elongate tube 306, e.g., intermediate the connectors 302, 304.

[0298] In use, the gases source 104 provides a flow of respiratory gases. The flow of respiratory gases may be heated and/or humidified by one or more of the humidifier 102, the heater wire 136 in the inspiratory conduit 130, and/or the upper airways of the patient before it is conveyed to the gases source 104 by the expiratory conduit 146. Some of the water molecules within the expiratory conduit 146 will be absorbed by the breathable material of the elongate tube 306. For example, water molecules may be absorbed from one or more of the flow of respiratory gases (e.g., in the form of water vapor), condensate (e.g., in the form of liquid water) which may form within the lumen, or condensate or other liquids which may have drained into the expiratory conduit 146 from other components of the respiratory assistance system 100. The water molecules may pass through the breathable material and be evaporated to ambient air by way of the solution-diffusion mechanism, driven by a difference in the concentration of water molecules within and outside the elongate tube.

[0299] As the breathable material absorbs water molecules, it may begin to expand in one or more of a longitudinal direction, a radial direction or a wall thickness. This may be referred to as a conditioned state. After a period of use under substantially constant conditions, the breathable material may reach a steady state, e.g., stop expanding.

[0300] FIG. 4 illustrates the expiratory conduit 146 of FIG. 3 in a conditioned state, e.g., as it might appear after a period of use. Evaporation of water molecules from the breathable material to ambient air 108 is represented by the arrows. [0301] Although shown arranged in a linear configuration for illustrative purposes, it will be appreciated that the expiratory conduit 146 may be flexible and, in use, may drape between the Y-piece 142 and the gases source 104. References to terms such as "longitudinal," "axis" and the like throughout the description and claims are not intended to imply that the expiratory conduit 146 must necessarily be arranged linearly.

[0302] Moreover, FIG. 4 is in schematic form and is not shown to scale. Proportions may be exaggerated for illustrative purposes. It is also to be appreciated that FIG. 4 illustrates one of a number of different possible conditioned states. The dimensions and mechanical properties of the expiratory conduit 146 may depend upon a number of variables including, but not limited to: time of use, temperature of the respiratory gases, humidity of the respiratory gases, temperature of the ambient air, humidity of the ambient air, movement of the ambient air, routing of the expiratory conduit, type and model of the gases source, type and model of the humidifier, patient condition and humidity contribution, or nebulized substances, for example.

[0303] As illustrated, the elongate tube 306 may expand in the longitudinal direction and in the radial direction. Although not apparent from FIG. 4, the elongate tube 306 may also expand in wall thickness.

[0304] As illustrated in FIG. 4, expansion of the expiratory conduit 146 in the radial direction is not necessarily uniform along a length of the expiratory conduit 146, e.g., intermediate the connectors 302, 304. Although not apparent from FIG. 4, expansion in the longitudinal direction and/or the wall thickness is not necessarily uniform along a length of the expiratory conduit 146, e.g., intermediate the connectors 302, 304.

[0305] The elongate tube 306 may tend to expand more in one or more regions than in one or more other regions. In some examples, localized expansion of the elongate tube 306 may occur in any one or more of an inlet region 402, an outlet region 404, or an intermediate region 406.

[0306] The inlet region 402 may be within, or correspond to, a portion of the length of the elongate tube 306 which is nearest one or more of the Y-piece 142, the patient interface 144, or the patient. In some examples, the inlet region 402 may be up to about 50%, up to about 33%, up to about 25%, up to about 20%, or up to about 10% of the length of the elongate tube 306 intermediate the connectors 302, 304.

[0307] It has been found that at least one of the relative or absolute humidity of the respiratory gases or the volume of condensate or other liquid within the lumen of the elongate tube 306 may be elevated in the inlet region 402, relative to one or more other regions of the elongate tube 306. The elevated humidity, relative to another region, may be due to the dehumidifying effect of the breathable material as the respiratory gases pass along the length of the lumen, for example. The elevated volume of condensate or other liquid in the inlet region 402 may be due to condensate or other liquid draining into the inlet region 402 from upstream of the expiratory conduit 146, e.g., one or more of the Y-piece 142, catheter mount, patient interface 144 or patient, for example. If the elongate tube 306 is corrugated, condensate or other liquids may accumulate within the corrugations in the inlet region 402.

[0308] The outlet region 404 may be within, or correspond to, a portion of the length of the elongate tube 306 which is nearest one or more of the filter, gases source 104, or gases return inlet 148. In some examples, the outlet region 404 may be up to about 50%, up to about 33%, up to about 25%, up to about 20%, or up to about 10% of the length of the elongate tube 306.

[0309] It has been found that at least one of the relative or absolute humidity of the respiratory gases or the volume of condensate or other liquid within the lumen of the elongate tube 306 may be elevated in the outlet region 404, relative to one or more other regions of the elongate tube 306. The elevated humidity or volume of condensate or other liquid may be due to condensate draining into the outlet region 30 from the filter or the gases source 104, for example.

[0310] The intermediate region 406 may be within, or correspond to, a portion of the length of the elongate tube 306 which is downstream of the inlet region 402 and upstream of the outlet region 404. The intermediate region 406 may be up to about 50%, up to about 33%, up to about 25%, up to about 20%, or up to about 10% of the length of the elongate tube 306.

[0311] It has been found that at least one of the relative or absolute humidity of the respiratory gases and the volume of condensate or other liquid within the lumen of the elongate tube 306 may be elevated in the intermediate region 406, relative to one or more other regions of the elongate tube 306. For example, relative to a region between the inlet region 402 and the intermediate region 406, or relative to a region between the intermediate region 406 and the outlet region 404. The flexibility of the expiratory conduit 146 means that the expiratory conduit 146 may tend to drape between the Y- piece 142 and the gases source 104. This draping may result in the intermediate region 406 being the lowest point of the expiratory conduit 146. And any condensate or other liquid within the lumen may tend to drain towards, and accumulate within, the intermediate region 406 due to gravity.

[0312] In FIG. 4, localized expansion in the radial direction is illustrated in the inlet region 402 and the outlet region 404. Localized expansion may appear as bulge 408 in a portion of the elongate tube 306. The bulge 408 may taper from its widest point towards an adjacent region of the elongate tube 306. If localized expansion occurs in two or more regions, one region, e.g., the inlet region 402, may expand more than another region, e.g., the outlet region 404. In some examples, it has been found that, in use, localized expansion may occur in one region, e.g., the inlet region 402, before it occurs in another region, e.g., the outlet region 404 or the intermediate region 406.

[0313] It is to be appreciated that the term "localized expansion" is not intended to mean that expansion is limited to one or more regions. The term is used in a relative sense. That is, expansion may be more pronounced in the regions of localized expansion than in an adjacent region.

[0314] It has been found that expansion of the breathable material may increase its permeability to water molecules, e.g., when compared to a more constrained breathable material under the same conditions. This may be due, at least in part, to the relatively greater surface area of the expanded breathable material.

[0315] Non-uniform expansion of the elongate tube 306 may advantageously increase the elongate tube's permeability to water molecules where it is most needed. For example, one or more of the inlet region 402, outlet region 404 and the intermediate region 406. The elongate tube 306 may automatically adapt to different or changing operating conditions, in use. By contrast, a water trap is provided in a fixed location along the length of the conduit. The fixed location may not necessarily coincide with the low point of the conduit. And corrugations in the elongate tube 306 may inhibit condensate or other liquid draining from one or more of the inlet region 402 or the outlet region 404 to the water trap, at least until sufficient condensate or liquid has accumulated to spill from one corrugation to the next.

[0316] In the example illustrated in FIG. 4, expansion of the elongate tube 306 may not be inhibited except by the connectors 302, 304. But in other examples, as described below, expansion of at least a portion of the elongate tube 306 may be inhibited in any one or more of the longitudinal direction, the radial direction, or the wall thickness. In some examples, the expiratory conduit 146 may be configured to expand more (e.g., as a proportion) in the radial direction than in the longitudinal direction. In some examples, the expiratory conduit 146 may be configured to expand predominately or only in the longitudinal direction. In other examples, the expiratory conduit 146 may be configured to expand predominately or only in one or more of the radial direction or the wall thickness.

Reinforcement member

[0317] FIG. 5 shows one example of an expiratory conduit 146, in schematic form. [0318] The expiratory conduit 146 may include one or more reinforcement members 502. The reinforcement member 502 may reduce the risk of partial or full occlusion of the elongate tube 306 when subject to an external mechanical force.

[0319] The reinforcement member 502 may be an internal reinforcement member, e.g., provided, at least in part, within the lumen of the elongate tube 306. In other examples, as described below, the reinforcement member may be an external reinforcement member, e.g., provided, at least in part, about the exterior of elongate tube 306.

[0320] The reinforcement member 502 may be fixedly attached to one or more of the connectors 302, 304 or the elongate tube 306. In some examples, respective ends of the reinforcement member 502 may be fixedly attached to connector 302 and connector 304. In other examples, the reinforcement member 502 may be attached to the expiratory conduit 146, e.g., by one or more clips. The clips may engage corrugations, e.g., an inner trough, of the elongate tube 306.

[0321] The reinforcement member 502 may have a helical shape. The reinforcement member 502 may be formed, at least in part, from a resilient material. The resilient material may be semi-rigid. The reinforcement member 502 may be configured to resiliently return to shape after it is compressed or extended. FIG. 5 illustrates the reinforcement member 502 in an extended state, exerting a force in a direction indicated by the arrows 504. This force may, at least in part, inhibit expansion of the elongate tube 306 in the longitudinal direction as it absorbs water molecules, in use.

[0322] In some examples, the reinforcement member 502 may impede expansion of the expiratory conduit 146, e.g., the elongate tube 306, in the longitudinal direction. The reinforcement member 502 may bias the expiratory conduit 146, e.g., the elongate tube 306, towards a predetermined length. The predetermined length may be about equal to a length of the expiratory conduit 146, when the elongate tube 306, without the reinforcement member 502, is in an equilibrated state. The expiratory conduit 146 may be configured so that the reinforcement member 502 is substantially unloaded when the expiratory conduit 146 is in an equilibrated state. The reinforcement member 502 may be configured to be in tension when the elongate tube 306 is in a conditioned state, e.g., when the elongate tube 306 expands in a longitudinal direction due to absorption of water molecules, in use.

[0323] In some examples, the reinforcement member 502 may improve a crush resistance of at least a portion of the expiratory conduit 146, e.g., at least a portion of the elongate tube 306, in one or more of an equilibrated state or a conditioned state. Crush resistance may refer to the ability of the expiratory conduit 146 to resist an applied force which acts to reduce the cross-sectional area of the lumen. Crush resistance may be tested by applying a force, e.g., of about 20 N, and measuring a resultant radial deformation of the expiratory conduit 146. In another example, crush resistance may be tested by measuring a force required for radial deformation of about 10 mm. An improvement in crush resistance due to the reinforcement member 502 may be assessed by comparing crush resistance of the conduit with and without the reinforcement member 502.

[0324] The reinforcement member 502 may be configured to be more rigid than the elongate tube 306, e.g., when the elongate tube 306 is in one or more of a conditioned state or a saturated state. For example, improved crush resistance in the inlet region 402 may reduce the risk of crushing or occlusion of the elongate tube by the patient's body, e.g., limbs, or between the patient's bed and other furniture.

[0325] In some examples, the reinforcement member 502 may improve a crush recovery of at least a portion of the expiratory conduit 146, e.g., at least a portion of the elongate tube 306. Crush recovery may refer to recovery of the expiratory conduit 146 to, or towards, an un-deformed state after removing a crushing force. Crush recovery may be measured by measuring a resistance to flow of the expiratory conduit 146 after applying and removing a load which substantially or completely occludes the expiratory conduit 146. An acceptable crush recovery may be less than about 150% of the resistance to flow before crushing. An improvement in crush recovery due to the reinforcement member 502 may be assessed by comparing crush recovery of the conduit with and without the reinforcement member 502.

[0326] In some examples, the reinforcement member 502 may not be attached to the elongate tube 306 at all. In some examples, the reinforcement member 502 may be fixedly attached to only the connectors 302, 304. In other examples, the reinforcement member 502 may be fixedly attached to the elongate tube 306 only at, or near, their respective ends, e.g., within the connectors 302, 304. The reinforcement member 502 may impede expansion of the expiratory conduit 146 in the longitudinal direction and/or improve one or more of crush resistance or crush recovery of the elongate tube 306. The reinforcement member 502 may allow for localized expansion, e.g., in the longitudinal direction, in one or more regions of the elongate tube 306, e.g., the inlet region 402. In some examples, that localized expansion may be compensated, at least in part, by localized compression of another portion of the elongate tube 306, e.g., between the inlet region 402 and the intermediate region 406.

[0327] In some examples, the reinforcement member 502 may be fixedly attached to the elongate tube 306 at a plurality of discrete locations along the length of the elongate tube 306, e.g., a plurality of discrete locations intermediate the connectors 302, 304. In some examples, as shown in FIG. 5, the elongate tube 306 may be corrugated. The reinforcement member 502 may be fixedly attached to the elongate tube 306 at each corrugation, or at every n corrugations (where n is a natural number). Such attachment between the reinforcement member 502 and the elongate tube 306 may impede expansion of at least a portion of the elongate tube 306 in the radial direction, and/or inhibit localized expansion of at least a portion of the expiratory conduit 146 in the longitudinal direction. In some examples, the reinforcement member 502 may be configured to permit at least some expansion in the longitudinal direction between consecutive attachments. Allowing some expansion may improve the permeability to water molecules of that portion of the elongate tube 306.

[0328] In some examples, a pitch of the helical reinforcement member 502 may vary along its length. The pitch may be measured as the distance between respective centers of adjacent coils of the reinforcement member 502. In some examples, the pitch may be varied so that the reinforcement member 502 impedes expansion of two or more regions of the elongate tube 306 to different degrees. For example, a reinforcement member 502 with a relatively lower pitch in the inlet region 402 may permit more expansion of the elongate tube 306, in the longitudinal direction, than in another region, e.g., the outlet region 404, in which the reinforcement member 502 has a relatively higher pitch. In some examples, the pitch may be varied so that the reinforcement member 502 provides different crush resistance or crush recovery to different regions of the elongate tube 306. For example, a reinforcement member 502 with a relatively lower pitch in the inlet region 402 may provide improved crush resistance of the expiratory conduit 146 in that region than in another region, e.g., the outlet region 404, in which the reinforcement member 502 has a relatively higher pitch.

[0329] FIG. 6 is a detailed perspective view of a portion of another example expiratory conduit including a reinforcement member 502.

[0330] The elongate tube 306 in this example may be uncorrugated, e.g., substantially smooth. In some examples, the reinforcement member 502 may improve one or more of crush resistance or crush recovery to the extent that corrugation is not required. An uncorrugated elongate tube may have a lower resistance to flow when compared to a corrugated elongate tube with the same maximum inside diameter (i.e., measured between inner troughs of a corrugation). Or an uncorrugated elongate tube 306 may have an inside diameter smaller than the maximum inside diameter of a corrugated tube with an equivalent resistance to flow. An uncorrugated elongate tube may allow condensate or other liquids to drain more freely, e.g., away from one or more of the patient, Y-piece 142, filter, or gases source 104, towards an intermediate region 406 of the elongate tube 306. [0331] Although not shown in FIG. 6, the expiratory conduit of FIG. 6 may also include connectors 302, 304 at respective ends of the elongate tube 306.

[0332] In some examples, as illustrated, the reinforcement member 502 may have a circular cross-section. In other examples, the reinforcement member 502 may have an elliptical cross-section. Or a polygonal cross-section, e.g., square or rectangular.

[0333] In some examples, the reinforcement member 502 may engage the elongate tube 306 continuously along at least a portion of the length, in the longitudinal direction, of the reinforcement member 502. For example, at least 25%, at least 50%, at least 75%, at least 90%, or about 100% of the total length of the reinforcement member 502, or a length of the reinforcement member 502 intermediate the connectors 302, 304. In some examples, the reinforcement member 502 may engage at least a portion of the elongate tube 306 continuously as described when the elongate tube 306 is in one state, e.g., one or more of a dry state or an equilibrated state, but not when the elongate tube 306 is in another state, e.g., one or more of a conditioned state or a saturated state. As the elongate tube 306 absorbs water molecules, in use, it may expand in both a longitudinal direction and a radial direction. Expansion of the elongate tube 306 in the longitudinal direction and the radial direction may be positively correlated. But a length and a diameter of the reinforcement member 502 may be inversely correlated. As the reinforcement member 502 is extended in the longitudinal direction by expansion of the elongate tube 306, its diameter may decrease. A reinforcement member 502 fixedly attached to the connectors 302, 304 at opposing ends may become spaced (or further spaced) from an inner surface of the elongate tube 306, in use.

[0334] In other examples, the reinforcement member 502 may be fixedly attached to the elongate tube 306, e.g., by an adhesive or welding. The reinforcement member 502 may be fixedly attached to the elongate tube 306 continuously along at least a portion of the length, in the longitudinal direction, of the reinforcement member 502. For example, at least 25%, at least 50%, at least 75%, at least 90%, or about 100% of the total length of the reinforcement member 502, or a length of the reinforcement member 502 intermediate the connectors 302, 304. Continuous attachment may better inhibit expansion of the elongate tube 306 in the radial direction. Some expansion in the radial direction may still be permitted between adjacent coils of the reinforcement member 502.

[0335] In other examples, the reinforcement member 502 may be embedded in the elongate tube 306. [0336] FIG. 7 is a schematic diagram of another example expiratory conduit 146 including a reinforcement member, in schematic form.

[0337] The reinforcement member 502 may have a non-helical shape, e.g., a linear or curvilinear shape. In some examples, the reinforcement member 502 may be substantially concentric with the elongate tube 306.

[0338] In some examples, a length of the reinforcement member 502 may be about equal to a length of the elongate tube 306.

[0339] In some examples, the reinforcement member 502 may be substantially inextensible, in use. Or when subjected to a force of up to about 10 Newtons (N), up to about 20 N, or up to about 45 N. A substantially inextensible reinforcement member 502 may be desirable in some applications where changes in length of the expiratory conduit 146 may be undesirable.

[0340] In other examples, the reinforcement member 502 may be resiliently extensible, in use. Or when subjected to a force of up to about 10 N, up to about 20 N, or up to about 45 N. A resiliently extensible reinforcement member 502 may permit some expansion of the elongate tube 306 in the longitudinal direction, which may increase breathability of the elongate tube 306.

[0341] The reinforcement member 502 may include a longitudinal portion 702 configured to extend along a length of at least a portion of the elongate tube 306. The longitudinal portion 702 may be located at about a center of the lumen of the elongate tube 306.

[0342] The reinforcement member 502 may include a plurality of radial portions 704. Each of the radial portions 704 may extend outwardly from the longitudinal portion. The radial portions may locate the longitudinal portion within the lumen, e.g., at about a center of the lumen. The radial portions 704 may improve one or more of a crush resistance or crush recovery of respective portions of the expiratory conduit 146. The radial portions 704 may each include a plurality of spokes, e.g., between 3 and 5 spokes, or 4 spokes. The spokes may be spaced equidistantly in a circumferential direction.

[0343] In some examples, one or more of the radial portions 704 may engage the elongate tube 306, e.g., with a friction fit or interference fit. A radial portion 704 may engage a corrugation of the elongate tube 306, e.g., an inner surface of the elongate tube at an inner trough. Such an engagement may inhibit relative movement between the reinforcement member 502 and the elongate tube 306 in the longitudinal direction. And inhibit expansion of the elongate tube 306 in the longitudinal direction. [0344] In some examples, one or more of the radial portions 704 may be fixedly attached to the elongate tube 306, e.g., by an adhesive or welding. Attachment between the radial portions 704 and the elongate tube 306 may inhibit expansion of at least a portion of the elongate tube 306 in one or more of the radial direction or the longitudinal direction.

[0345] In some examples, one or more of the radial portions 704 may engage a connector 302, 304. A radial portion 704 at each end of the reinforcement member 502 may engage a respective one of the connectors 302, 304. These end radial portions 704 may differ to radial portions 704 engaging the elongate tube 306.

[0346] FIG. 8 is a detailed view of another example expiratory conduit including a reinforcement member, in schematic form.

[0347] The reinforcement member 502 in this example is an external reinforcement member. The reinforcement member 502 is provided about the elongate tube 306. The reinforcement member 502 may have a helical shape, e.g., a double helix structure.

[0348] In some examples, the external reinforcement member 502 may inhibit expansion of at least a portion of the elongate tube 306 in both the radial direction and the longitudinal direction.

[0349] The reinforcement member 502 may bias the expiratory conduit 146, e.g., the elongate tube 306, towards a predetermined length. Similar to the reinforcement member of FIG. 5.

[0350] In some examples, the reinforcement member 502 may be spaced from the elongate tube 306, e.g., when the elongate tube 306 is in one or more of a dry state or an equilibrated state. That is, the reinforcement member 502 does not closely conform to the outer surface of the elongate tube. This spacing may allow the elongate tube 306 to expand relatively freely in the radial direction before further expansion is inhibited by the reinforcement member 502.

[0351] In other examples, the reinforcement member 502 may closely conform to the outer surface of the elongate tube 306, or at least the outer surface of the outer peaks of a corrugated elongate tube 306. The reinforcement member 502 may be resilient, allowing for at least some expansion of the elongate tube 306 in the radial direction.

[0352] Although not shown in FIG. 8, the expiratory conduit may include connectors 302, 304. Respective ends of the reinforcement member 502 may be fixedly attached to the connector 302 and the connector 304. In some examples, the reinforcement member 502 is not fixedly attached to the elongate tube 306 at all. In other examples, the reinforcement member 502 may be fixedly attached to the elongate tube 306 at one, two, three or more discrete locations, or continuously.

[0353] In some examples, the reinforcement member 502 may be formed, at least in part, from a polymer material such as polypropylene.

[0354] FIG. 9 is a detailed view of another example expiratory conduit including a reinforcement member, in schematic form.

[0355] The reinforcement member 502 in this example is an external reinforcement member.

[0356] The reinforcement member 502 may include a plurality of annular members 902. The annular members 902 may extend about a circumference of the elongate tube 306. The annular members 902 may be substantially coaxial with the elongate tube 306 and/or each other. One or more of the annular members 902 may be configured to engage one or more corrugations of a corrugated elongate tube 306, e.g., in an interference fit. The annular members 902 may occupy, at least in part, the outer trough between consecutive outer peaks of the corrugated elongate tube 306. Engagement between an annular member 902 and a corrugation may inhibit relative movement in the longitudinal direction. Which may inhibit expansion of at least a portion of the elongate tube in the longitudinal direction, e.g., between adjacent annular members 902.

[0357] In some examples, the reinforcement member 502 may have between 10 and about 200 annular members 902. In some examples, the reinforcement member 502 may have one annular member 902 for between every 2 and 50 corrugations, or between every 4 and 40 corrugations, of the elongate tube 306. In some examples, the elongate tube 306 may have between 400 and 450 corrugations, or between 410 and 430 corrugations, e.g., 418 corrugations. And the reinforcement member 502 may have between 2 and 209 annular members 902, or between 8 and 100 annular members 902.

[0358] The annular members 902 may inhibit expansion of at least a portion of the elongate tube 306 in the radial direction.

[0359] The reinforcement member 502 may include a plurality of longitudinal members 904. The longitudinal members 904 may each extend between, and space apart, adjacent pairs of the annular members 902. In some examples, there may be between 1 and 8 longitudinal members 904, or between 2 and 4 longitudinal members 904 between each consecutive pair of annular members 902. The longitudinal members 904 may be rotationally offset between two or more adjacent pairs of the plurality of annular members. The longitudinal members 904 may have a smaller cross-sectional area than the annular members 902.

[0360] The plurality of longitudinal members 904 may inhibit expansion of at least a portion of the elongate tube 306 in the longitudinal direction. The plurality of longitudinal members 904 may inhibit expansion of at least a portion of the elongate tube 306 in the radial direction.

[0361] The annular members 902 and the longitudinal members 904 together may form an openwork structure. The openwork structure may include a number of openings 906. The openings 906 may allow for evaporation of water molecules from the breathable material of the elongate tube 306 to ambient air. In some examples, the openwork structure may be configured to leave at least about 25%, at least about 50%, at least about 75%, or at least about 85% of the elongate tube 306 exposed to ambient air 108.

[0362] In some examples, reinforcement member 502 may be formed, at least in part, from a resilient material, e.g., an elastomeric material.

[0363] In some examples, the reinforcement member 502 may closely conform, at least in part, to the outer surface of the elongate tube 306, or at least the outer peaks of a corrugated elongate tube 306, when the expiratory conduit 146 is in one or more of a dry state or an equilibrated state. In other examples, at least a portion of the reinforcement member 502 may be spaced from the elongate tube 306 about a circumference of the elongate tube 306, when the expiratory conduit 146 is in one or more of a dry state or an equilibrated state.

[0364] FIG. 10 is a detailed view of another example expiratory conduit including a reinforcement member, in schematic form.

[0365] The reinforcement member 502 in this example is an external reinforcement member. The reinforcement member 502 may be in the form of a sheath. The reinforcement member 502 may be non-braided.

[0366] The expiratory conduit 146 of FIG. 10 is shown in an equilibrated state, e.g., prior to use.

[0367] In some examples, the reinforcement member 502 may be malleable, e.g., formed, at least in part, from a malleable material such as a malleable alloy. The malleable alloy may be covered with a polymer material, e.g., an elastomeric polymer material. The polymer material may be overmolded to the malleable alloy. The malleable reinforcement member 502 may be self-supporting. The reinforcement member 502 may be manipulated by the user to provide a constrained route for the elongate tube 306. The reinforcement member 502 may be manipulated to vary how much expansion of the elongate tube 306 is inhibited, e.g., in the radial direction, in different regions of the expiratory conduit 146. For example, in one region the reinforcement member 502 may be manipulated to closely conform to the elongate tube 306, e.g., when it is in an equilibrated state. In a second region, the reinforcement member 502 may be manipulated so that it is at least partially spaced from an outer surface of the elongate tube 306. Expansion of the elongate tube 306 in the radial direction may thereby be inhibited more in the first region than in the second region.

[0368] In some examples, the reinforcement member 502 may be formed, at least in part, from a shape-memory material, e.g., a shape-memory alloy or shape-memory polymer. The reinforcement member 502 may be deformed by a temperature change of the elongate tube, in use. Warming of the elongate tube may heat the shape-memory material to produce the deformation. The reinforcement member 502 may return to a "remembered" shape when heated. In some examples, the shape-memory material may be configured to adopt a shape allowing the elongate tube 306 to expand, e.g., in a radial direction, more in one region, e.g., the inlet region 402, than in another region.

[0369] FIG. 11 illustrates the expiratory conduit 146 of FIG. 10 in a conditioned state, e.g., as it might appear after a period of use. Localized expansion can be observed at the inlet region 402 near the connector 302.

[0370] A reinforcement member 502 formed from a malleable material may be manipulated to permit the localized expansion, e.g., if condensate or other liquid is found to have accumulated in that region. In other examples, the reinforcement member 502 may be configured to be deformed by the expansion of the elongate tube 306.

[0371] A reinforcement member 502 formed from a shape-memory material may adopt the "remembered" shape when exposed to heat from the respiratory gases conveyed by the elongate tube 306, in use.

Wicking

[0372] In some examples, an internal reinforcement member 502 may be configured to wick condensate or other liquid within the lumen of the elongate tube 306, in use.

[0373] The reinforcement member 502 may include one or more grooves. The one or more grooves may provide wicking, at least in part, by capillary action. Forming one or more grooves into the reinforcement member 502 may provide a narrow path that may be configured to transport liquid via capillary action. This capillary wicking may be caused by the force of adhesion between the liquid and the surface, and by the surface tension of the liquid. The wicking effect may also be affected by external forces, such as gravity. The capillary forces may be sufficient to wick liquid a substantial distance against the gravitational force.

[0374] Improving the wicking properties of the reinforcement member 502 may be achieved by varying or altering the dimensions and/or shape of the grooves. In some examples, a groove may extend as far as possible into the reinforcement member 502 to increase the surface area and/or the cross-sectional area of the groove. The depth may be limited by the dimensions of the reinforcement member 502. The depth of the grooves formed into the reinforcement member 502 may be selected to maintain the structural integrity of the reinforcement member 502 and/or the expiratory conduit 146.

[0375] In some examples, the grooves may be relatively narrow in comparison to the depth in order to maintain a high surface area to volume ratio. For capillary wicking, such a configuration may increase one or more of the speed at which liquid is transported along the groove or the distance, e.g., height, the liquid can be transported.

[0376] In some examples, the grooves may be relatively wide in comparison to the depth. Having a wider groove may provide benefits in the volume of liquid that can be transported though capillary wicking. Although the speed may not be as fast as a narrow groove, the increased cross-section of the groove may provide a greater overall flow rate. This could be useful in redistributing larger volumes of liquid, where the overall flow rate may be more important than the speed and/or distance of the overall wicking.

[0377] Further details of wicking are disclosed in International Patent Application Publication No. WO 2019/203664 Al, the entire content of which is incorporated herein by reference.

[0378] FIG. 12 shows an isometric view of another example expiratory conduit 146.

[0379] The expiratory conduit 146 is shown in an equilibrated state. It is not shown to scale.

[0380] The expiratory conduit 146 in this example includes a braided sheath 1202. The braided sheath 1202 is provided about an outer surface of the elongate tube 306. The braided sheath may be configured to fit loosely about the elongate tube 306, e.g., not engage the elongate tube 306 about its entire circumference, in the equilibrated state.

[0381] One or more of the connectors 302, 304 may include one or more apertures, e.g., a pair of apertures 1204. In some examples, as shown in FIG. 12, each connector includes only two apertures 1204, i.e., a single pair of apertures 1204. The apertures 1204 may extend through a cylindrical wall of the connector. The apertures may be radial apertures. One or more of the elongate tube 306 or braided sheath 1202 may be exposed through the apertures 1204. The pair of apertures 1204 may be diametrically opposed. The pair of apertures 1204 may be identical to each other in size and/or shape. The pair of apertures 1204, in combination, may extend around more than 80%, or more than 90%, of a circumference of the respective connector 302, 304.

[0382] The connectors 302, 304 may be generally cylindrical. A distal portion of the connector, e.g., connector 302, may extend distally of the elongate tube 306. The distal portion may include a conical connector as described above. The distal portion may be configured to establish and maintain a pneumatic connection with one or more of the Y- piece 142, the gases source 104, or an optional filter. A proximal portion of the connector, e.g., connector 302, may extend about and/or within an end of one or more of the elongate tube 306 or braided sheath 1202. The proximal portion may be configured to secure the connector to the elongate tube 306. In some examples, the proximal portion of the connector extends both about and within an end of the elongate tube 306 and the braided sheath 1202. One or more of the elongate tube 306 or the braided sheath 1202 may be secured, e.g., clamped, within the proximal portion of the connector, e.g., between an outer part of the proximal portion and an inner part of the proximal portion. The apertures 1204 may be located in the proximal portion, e.g., the outer part of the proximal portion.

[0383] The braided sheath 1202 is fixedly attached to the elongate tube 306 (obscured by the braided sheath in FIG. 12) by the connectors 302, 304. The connectors 302, 304, may be overmolded, at least in part, to the braided sheath 1202 and the elongate tube 306.

[0384] One or more of the connectors 302, 304 may be formed in two parts. A first part may be injection molded. A second part may be overmolded. The second part may be overmolded to the first part, the elongate tube 306 and the braided sheath 1202. The first part may form at least the inner part of the proximal portion. The second part may form at least the outer part of the proximal portion. The apertures 1204 may be located in the second part. The apertures 1204 may form through-holes in the second part, but blind holes in the complete connector assembly and/or conduit.

[0385] The apertures 1204 may advantageously allow at least two or more of the elongate tube 306, braided sheath 1202, and the first component of the connector to be clamped together, e.g., within a mold tool, as the second part is overmolded. [0386] In some examples, as shown in FIG. 12, the braided sheath 1202 is not attached to the elongate tube 306 intermediate the connectors 302, 304. In other examples, as described above, there may be an intermediate connector attaching the braided sheath 1202 and the elongate tube 306.

[0387] A length and a diameter of the braided sheath 1202 may be negatively related. For example, as the braided sheath 1202 lengthens, it becomes narrower.

Tethering

[0388] In some examples, a medical gases conduit may be tethered, at least in part, with another medical gases conduit.

[0389] FIG. 13 shows the expiratory conduit 146 of FIG. 4 and FIG. 5, tethered to the inspiratory conduit 130 of the respiratory assistance system 100.

[0390] In some examples, the inspiratory conduit may include a pair of connectors 1302, 1304 and an elongate tube 306, like the expiratory conduit 146.

[0391] The elongate tube 1306 of the inspiratory conduit may be formed from a non- breathable material, e.g., a polyolefin such as polyethylene or polypropylene. That is, the elongate tube 1306 is not formed from a breathable material. Such materials tend not to expand, in use. Or expand only negligibly, e.g., less than 5%, or less than 1%, in one or more of the radial direction or longitudinal direction, in immersion testing. In some examples, the elongate tube 1306 of the inspiratory conduit 130 may be less breathable than elongate tube 306 of the expiratory conduit 146. In some examples, the elongate tube 1306 of the inspiratory conduit 130 may expand less than the elongate tube 306 of the expiratory conduit 146, in use.

[0392] The expiratory conduit 146 may be configured to expand more than the inspiratory conduit 130 in at least the longitudinal direction, in use. The difference in expansion may be observable to the naked eye.

[0393] The expiratory conduit 146, e.g., elongate tube 306, may be tethered to the inspiratory conduit 130, e.g., elongate tube 1306, by one or more retainers 1308. In some examples, there may be between 2 and 120 retainers 1308, between 3 and 60 retainers 1308, or between 4 and 40 retainers 1308. In some examples, there may be one retainer for between every 4 and 50 corrugations of the expiratory conduit 146.

[0394] In some examples, as illustrated, the retainers 1308 may be separate from each other. In other examples, as described below, two or more of the retainers 1308 may be physically connected or connectable to each other. [0395] Each of the retainers 1308 may be integrally formed, e.g., by injection molding.

[0396] The retainers 1308 may be spaced, or configured to be spaced, along a length of the inspiratory conduit 130 and the expiratory conduit 146. In some examples, at least some of the retainers 1308 may be spaced equidistantly. In some examples, the spacing between at least some of the retainers 1308 may be varied.

[0397] The retainers 1308 may be positioned so that the inspiratory conduit 130 and the expiratory conduit 146 may diverge at one end to connect with the humidifier 102 and the gases source 104, respectively.

[0398] Each of the retainers 1308 may be removably engageable and re-engageable with respective portions of each of the inspiratory conduit 130 and the expiratory conduit 146. And may maintain at least the respective portions of the inspiratory conduit 130 and the expiratory conduit 146 in a side-by-side relationship.

[0399] The retainers 1308 may engage the inspiratory conduit 130 and expiratory conduit 146 in such a way as to inhibit movement of the inspiratory conduit 130 and the expiratory conduit 146 in the longitudinal direction, relative to the retainer 1308. And the inspiratory conduit 130 or the expiratory conduit 146 may be inhibited from sliding through the retainer 1308. In some examples, the retainers 1308 may engage a corrugation, e.g., an outer trough, in one or more of the inspiratory conduit 130 or the expiratory conduit 146 in an interference fit. In some examples, the retainers 1308 may engage one or more of the inspiratory conduit 130 or the expiratory conduit 146 with a friction fit.

[0400] The retainers 1308 and the inspiratory conduit 130, in combination, may inhibit expansion of at least a portion of the expiratory conduit 146, e.g., between adjacent retainers 1308, in the longitudinal direction.

[0401] The retainers 1308 may inhibit expansion of the elongate tube 306 in the radial direction by substantially surrounding at least a majority of a circumference of a portion of the elongate tube 306. In some examples, the retainers 1308 may fit loosely about the circumference of the elongate tube 306, in at least the equilibrated state. This may allow for some expansion of the elongate tube 306 in the radial direction before further expansion is inhibited. In other examples, the retainers 1308 may conform closely about a circumference of the elongate tube 306, in the equilibrated state. Or even exert a slight compressive force, gripping the elongate tube 306.

[0402] As shown in FIG. 13, the expiratory conduit 146 may expand in a radial direction intermediate adjacent pairs of the retainers 1308. In some examples, the retainers 1308 may also allow for some radial expansion within the retainer 1308. [0403] The retainers 1308 may improve the crush resistance of at least a portion of the expiratory conduit 146. Crush resistance may be further improved by increasing the number or density of the retainers 1308.

[0404] The inspiratory conduit 130 may improve the crush resistance of the expiratory conduit 146. For example, a crush resistance of the inspiratory conduit 130 may limit the compressive force applied to the adjacent expiratory conduit 146. A crush resistance of a combination of the inspiratory conduit 130 and the expiratory conduit 146 may be greater than a crush resistance of the expiratory conduit 146 alone.

[0405] Tethering the inspiratory conduit 130 and the expiratory conduit 146 may provide some passive heating of the expiratory conduit 146, in use. Passive heating may be provided by the heated and humidified flow of respiratory gases conveyed by the inspiratory conduit 130, and/or the heater wire 136 of the inspiratory conduit 130. The passive heating may reduce formation of condensate within the lumen of the expiratory conduit 146. In some examples, the retainers 1308 may be formed, at least in part, from a thermally conductive material such as a metallic alloy, e.g., an aluminum alloy. In other examples, the retainers 1308 may be formed from a polymer material such as a polyolefin, e.g., polyethylene or polypropylene.

[0406] Tethering the inspiratory conduit 130 and the expiratory conduit 146 together may be tidier and less intrusive than allowing the inspiratory conduit 130 and the expiratory conduit 146 to drape independently.

[0407] In some examples, as illustrated, the inspiratory conduit 130 and the expiratory conduit 146 may be spaced from each other. A spacing between the conduits may allow the expiratory conduit 146 to expand more in the radial direction, and/or improve breathability by exposing a larger surface area of the elongate tube 306 to ambient air. In other examples, the inspiratory conduit 130 and the expiratory conduit 146 may arranged close together, or even in abutment. Abutment may provide improved heat transfer from the inspiratory conduit 130.

[0408] The number of retainers 1308 used may depend upon a number of factors, including one or more of the length of the conduits 130, 146, the width of the retainers 1308, the potential for absorption or expansion of the expiratory conduit 146, or rigidity of the inspiratory conduit 130.

[0409] The retainers 1308 may be provided with one or more of the inspiratory conduit 130 and/or the expiratory conduit 146 in a respiratory breathing circuit kit. In some examples, the retainers 1308 may be pre-assembled with one or more of the inspiratory conduit 130 and/or the expiratory conduit 146. [0410] FIG. 14 shows a detailed view of an inspiratory conduit 130, an expiratory conduit 146, and a plurality of retainers 1308 according to another example.

[0411] In some examples, as shown in FIG. 14, each of the retainers 1308 may be identical or substantially identical.

[0412] Each of the retainers 1308 may include a pair of retaining members. In some examples, each of the pair of retaining members may be a clip 1402. One of the pair of retaining members may be configured to extend about the inspiratory conduit 130, e.g., elongate tube 1306. The other of the pair of retaining members may be configured to extend about the expiratory conduit 146, e.g., elongate tube 306. Each retainer 1308 is thereby configured to independently retain the inspiratory conduit 130 and the expiratory conduit 146. This independence may allow a medical professional to remove and/or replace one of the conduits, if required. But in other examples, the retainers 1308 may each include a single retaining member configured to extend about both the inspiratory conduit 130 and the expiratory conduit 146.

[0413] The clips 1402 may be part-annular. The clips 1402 may define an opening 1404 through which the respective conduit 130, 146, e.g., elongate tube 1306, 306, may be received into an interior portion. The clips 1402 may be configured so that one or more of the clip 1402 or the elongate tube 1306, 306 resiliently deforms as the elongate tube 1306, 306 is forced through the opening 1404. The clips 1402 may partially or fully recover. The openings 1404 of the pair of clips 1402 may face in opposing directions. In some examples, the pair of clips 1402 may be identical, e.g., a mirror-image of each other. In other examples, the pair of clips 1402 may differ, e.g., to accommodate a differing inspiratory conduit 130 and expiratory conduit 146, e.g., elongate tube 1306 and elongate tube 306.

[0414] Each of the clips 1402 may diverge outwardly adjacent the opening 1404. This divergence may help guide a conduit to, and through, the opening 1404.

[0415] In some examples, one or more projections may project inwardly from an interior surface of the clips 1402. The projections may be configured to occupy, at least in part, the outer trough between adjacent outer peaks of the corrugated elongate tube 306. The projection may inhibit or prevent relative movement between the clip 1402 and the inspiratory conduit 130 or the expiratory conduit 146 in the longitudinal direction and, optionally, still allowing for some expansion of the conduit in the radial direction. Or an engaging surface of the retainers 1308 may be shaped to complement the corrugation profile of the expiratory conduit 146. [0416] In other examples, each of the retaining members may include a strap. The strap may be configured to wrap around a respective one of the conduits 130, 146. Each strap may be secured by a fastener, e.g., a hook-and-loop fastener.

[0417] In some examples, at least some of the retaining members may be resilient. A resilient retaining member may be configured to deform in use to allow some expansion of the expiratory conduit 146 in the radial direction. Yet still inhibit expansion to at least some degree. Or inhibit expansion in the longitudinal direction.

[0418] In some examples, at least some of the retaining members may be adjustable, e.g., the retaining members configured to receive and retain the expiratory conduit 146. This may allow a user to adjust each of the retaining members to allow more or less expansion of the expiratory conduit 146 in the radial direction in one or more regions of the expiratory conduit 146.

[0419] FIG. 15 shows an isometric view of pair of the retainers 1308 of FIG. 14, in isolation.

[0420] Two or more retainers 1308 may be directly physically connected to each other. Each of the retainers 1308 may include a first connector and a second connector. The first connector of one retainer 1308 may be configured to establish a mechanical connection with the second connector of another retainer 1308. In some examples, the mechanical connection may be one or more of a snap-fit connection, a pivotable connection, or a ball-and-socket connection. A pivotable connection may have one or more degrees of freedom. A ball-and-socket connection may have three degrees of freedom.

[0421] In some examples, as shown in FIG. 14, the first connector may be a ball connector 1502 and the second connector may be a socket 1504. The ball connector 1502 of one retainer 1308 may be engaged with the socket 1504 of another retainer 1308 to establish a ball-and-socket connection.

[0422] In some examples, at least one of the plurality of retainers 1308 may include only the first connector, i.e., not the second connector, and/or at least one of the plurality of retainers 1308 may include only the second connector, i.e., not the first connector. The retainers 1308 with a single connector may be configured to be provided at respective ends of a chain of connected retainers 1308.

[0423] In some examples, the mechanical connection may be configured to permit relatively free movement between two connected retainers 1308. This may allow one or more of the inspiratory conduit 130 or expiratory conduit 146 to flex freely, in use, e.g., to drape naturally between the Y-piece 142 and the gases source 104. In other examples, the mechanical connection may be configured to resist pivotal movement between two connected retainers 1308, in use. This may allow the retainers 1308 to be manipulated to define a constrained route for the inspiratory conduit 130 or expiratory conduit 146, at least in part.

[0424] FIG. 16 shows a cross-sectional view of the pair of retainers 1308 shown in FIG. 15.

[0425] The ball connector 1502 of one of the pair of retainers 1308 is shown connected with the socket 1504 of the other of the pair of retainers 1308.

[0426] The retainers 1308 may each include an arm 1602. The arm may be configured to space one retainer 1308 from another. And in particular, space the clips 1402 of one retainer 1308 from the clips 1402 of a connected retainer 1308. In some examples, the arms may be configured to define a fixed spacing between adjacent pairs of the plurality of retainers. The first connector, e.g., ball connector 1502, may be provided at a distal end of the arm 1602. The second connector, e.g., socket 1504 may be provided at, or near, a proximal end of the arm 1602. The clips 1402 may be provided at, or near, a proximal end of the arm 1602.

[0427] In some examples, the plurality of retainers may include at least one retainer 1308 without an arm. The retainer 1308 without an arm 1602 may be configured to be provided at the end of a chain of connected retainers 1308, e.g., so that there is no protruding arm which may catch, e.g., on bedding, clothing, furniture, people or the like. The retainer 1308 may omit both the arm 1602 and the first connector, e.g., ball connector 1502.

[0428] The ball-and-socket connection may permit a range of motion between two retainers 1308. The range of motion may be selected to reduce a risk that one or more of the inspiratory conduit 130 or the expiratory conduit 146 will kink, in use.

Corrugation profiles

[0429] In some examples, a medical gases conduit may be corrugated.

[0430] The corrugations may have a particular corrugation profile. The corrugation profile may be different to one or more of known medical gases conduits or the inspiratory conduit 130. The modified corrugation profile may increase one or more of a stiffness, crush resistance, or crush recovery of the elongate tube 306. Particularly when the elongate tube 306 is in the conditioned state or the saturated state. The corrugation profile may impede expansion of the expiratory conduit 146 in one or more of the radial direction, the longitudinal direction or the wall thickness. [0431] FIG. 17 shows a detailed view, in cross-section, of the elongate tube 306 of an expiratory conduit 146 with an example corrugation profile, e.g., in an equilibrated state.

[0432] Each corrugation may have an outer peak 1702. In some examples, as shown, the outer peak 1702 may be rounded. In some examples, the outer peak 1702 is not flattened, e.g., does not define a cylindrical surface. The outer peak 1702 may have a first radius of curvature 1704.

[0433] Each corrugation may have an outer trough 1706. In some examples, as shown, the outer trough 1706 may be rounded. In some examples, the outer trough 1706 is not flattened, e.g., does not define a cylindrical surface. The outer trough 1706 may have a second radius of curvature 1708. The second radius of curvature 1708 may be smaller than the first radius of curvature 1704.

[0434] Each corrugation may have an inner peak 1710. The inner peak 1710 may be at an inner surface of the tube wall opposing the outer trough 1706 at the outer surface of the tube wall. In some examples, as shown, the inner peak 1710 may be rounded. In some examples, the inner peak 1710 is not flattened, e.g., does not define a cylindrical surface. The inner peak 1710 may have a third radius of curvature 1712. In some examples, the third radius of curvature 1712 may be about equal to the first radius of curvature 1704. In some examples, the third radius of curvature 1712 may be larger than the second radius of curvature 1708.

[0435] Each corrugation may have an inner trough 1714. The inner trough 1714 may be at an inner surface of the tube wall opposing the outer peak 1702 at the outer surface of the tube wall. In some examples, as shown, the inner trough 1714 may be rounded. In some examples, the inner trough 1714 is not flattened, e.g., does not define a cylindrical surface. The inner trough 1714 may have a fourth radius of curvature 1716. In some examples, the fourth radius of curvature 1716 may be smaller than the first radius of curvature 1704. In some examples, the fourth radius of curvature 1716 may be about equal to the second radius of curvature 1708. In some examples, the fourth radius of curvature 1716 may be smaller than the third radius of curvature 1712.

[0436] In some examples, as shown in FIG. 17, a cross-section of the tube wall at the outer peak 1702 and the inner trough 1714 may be similar to, e.g., a mirror-image of, a cross-section of the tube wall at the outer trough 1706 and the inner peak 1710.

[0437] Each corrugation may have a pair of side walls 1718. The side walls 1718 may be substantially straight. The side walls 1718 may be angled to converge towards the respective outer peak/outer trough (or inner peak/inner trough). In some examples, the side walls 1718 may be angled towards 90 °, e.g., between about ±60 ⁰ and ±90 °, or between about ±77.5 ⁰ and ±90 °, with respect to the longitudinal direction.

[0438] In some examples, as shown in FIG. 17, the corrugation profile may be generally sinusoidal in shape.

[0439] The corrugation profile may be substantially uniform along a length of the elongate tube 306. In other examples, the elongate tube 306 may have include a composite corrugation profile. In an elongate tube 306 including a composite corrugation profile, the corrugation profile may vary along a length of the elongate tube 306, e.g., differ between two or more regions of the elongate tube 306. This may allow one or more of stiffness, crush resistance, crush recovery, or expansion to be tailored to different regions of the elongate tube 306.

[0440] In some examples, the corrugations may have a particular pitch, e.g., measured as the distance between consecutive outer peaks of the corrugated elongate tube 306. The pitch of the expiratory conduit 146 may be smaller than a pitch of the inspiratory conduit 130. In other words, the expiratory conduit 146 may have more corrugations than the inspiratory conduit 130. A lower pitch may increase the number of side walls 1718, which may increase one or more of a stiffness, crush resistance or crush recovery of the elongate tube 306. Particularly when the elongate tube 306 is in the conditioned state or the saturated state. In some examples, the expiratory conduit 146, e.g., elongate tube 306, may have a pitch of between about 1 mm and 3.5 mm, between about 2 mm and 3.5 mm, or between about 2 mm and 3 mm, e.g., in the equilibrated state. In some examples, a pitch of the expiratory conduit 146, e.g., in the equilibrated state, may be less than a pitch of the inspiratory conduit 130.

[0441] Although not shown in FIG. 17, at least one end of the elongate tube 306 may be uncorrugated. At least one of the connectors 302, 304 may be fixedly attached to an uncorrugated end portion. In some examples, the connectors 302, 304 may, at least in part, be overmolded to uncorrugated end portions of the elongate tube 306.

[0442] In some examples, a wall thickness of the elongate tube 306 may be substantially uniform along the length of the elongate tube 306, or at least intermediate the connectors 302, 304. In other examples, a wall thickness of the elongate tube 306 may vary along the length of the elongate tube 306, e.g., differ between two or more different regions of a corrugation and/or the elongate tube 306. This may allow one or more of stiffness, crush resistance, crush recovery, or expansion to be tailored to different regions of the elongate tube 306. [0443] In some examples, the corrugation profiles may be uniform about a circumference of the elongate tube 306, e.g., in one or more of a dry state or an equilibrated state. The elongate tube 306 may have rotational symmetry about its axis.

[0444] In some examples, the elongate tube 306 may include one or more ribs on one or more of an inner surface or outer surface of the elongate tube 306. In some examples, one or more ribs, e.g., two ribs, may extend in the longitudinal direction. The two longitudinal ribs may be provided on opposing sides of the elongate tube 306. In some examples, one or more ribs may extend in a circumferential direction.

[0445] FIG. 18 shows a detailed view, in cross-section, of the elongate tube 306 of an expiratory conduit 146 with another example corrugation profile, e.g., in an equilibrated state.

[0446] In some examples, any one or more of the outer peak 1702, the outer trough 1706, the inner peak 1710 or the inner trough 1714 may be flattened, e.g., define a cylindrical surface. In some examples, as shown, all four of the outer peak 1702, outer trough 1706, inner peak 1710 and inner trough 1714 may be flattened, e.g., define respective cylindrical surfaces. The flattened peaks/troughs may reduce a likelihood of the corrugation "rotating," which may expand the elongate tube 306. Rotating being the pivoting of the various faces towards a "flat" elongate tube 306.

[0447] In the example of FIG. 18, the side walls 1718 may be provided at a steeper angle, e.g., at about ±80°, than in the example of FIG. 17. The steeper angle may increase one or more of the stiffness or crush resistance of the elongate tube 306, relative to a shallower angle, e.g., when the elongate tube 306 is in the conditioned state.

[0448] FIG. 19 shows a detailed view, in cross-section of another possible corrugation profile of an expiratory conduit 146, e.g., in an equilibrated state.

[0449] The outer peak 1702 in this example is not flattened, e.g., does not define a cylindrical surface. The outer peak 1702 is rounded.

[0450] The outer trough 1706 in this example is flattened, e.g., defines a cylindrical surface.

[0451] The inner peak 1710 in this example is flattened, e.g., defines a cylindrical surface. [0452] The inner trough 1714 in this example is not flattened, e.g., does not define a cylindrical surface. The inner trough 1714 is rounded. The inner trough 1714 has a smaller radius of curvature than the outer peak 1702.

[0453] Each corrugation may have an inner trough 1714. The inner trough 1714 may be at an inner surface of the tube wall opposing the outer peak 1702 at the outer surface of the tube wall. In some examples, as shown, the inner trough 1714 may be rounded. In some examples, the inner trough 1714 is not flattened, e.g., does not define a cylindrical surface. The inner trough 1714 may have a fourth radius of curvature 1716. In some examples, the fourth radius of curvature 1716 may be smaller than the first radius of curvature 1704. In some examples, the fourth radius of curvature 1716 may be about equal to the second radius of curvature 1708. In some examples, the fourth radius of curvature 1716 may be smaller than the third radius of curvature 1712.

Breathable Membrane

[0454] In some examples, a medical gases conduit may include a membrane formed, at least in part, from a breathable material.

[0455] FIG. 20 shows a detail view of an example expiratory conduit 146 including a membrane 2002.

[0456] A membrane 2002 may have a higher moisture vapor transmission rate (MVTR) than a thicker tube wall formed from the same breathable material.

[0457] In some examples, the membrane 2002 may be an external membrane. The membrane 2002 may be provided about the elongate tube 306. The membrane 2002 may form a sleeve about the elongate tube 306. The membrane 2002 may directly engage, e.g., abut, the elongate tube 306. The elongate tube 306 may be corrugated. In some examples, as shown in FIG. 20, the membrane 2002 may conform, at least in part, to the outer surface of the permeable elongate tube 306, e.g., to outer peaks of the corrugated elongate tube 306 as illustrated, e.g., when the expiratory conduit 146 is in an equilibrated state. The membrane 2002 may drape between adjacent outer peaks of the permeable elongate tube 306. The drape may improve the flexibility of the expiratory conduit 146. The membrane 2002 may adopt, at least in part, the corrugation profile of the elongate tube 306. In other examples, the membrane 2002 may be relatively taut.

[0458] The membrane 2002 may be thinner than the wall thickness of the elongate tube 306. In some examples, the membrane 2002 may have a wall thickness of less than about 200 micrometers (pm), less than about 100 pm, less than about 80 pm, less than about 60 pm, or less than about 40 pm, e.g., about 20 pm. In some examples, the membrane 2002 may have a wall thickness of between about 2% and 30%, or between about 5% and 20%, of the wall thickness of the elongate tube 306 in the dry state or the equilibrated state.

[0459] One or more airgaps 2004 may be formed between the membrane 2002 and the elongate tube 306. For example, between the membrane 2002 and the outer troughs of the elongate tube 306. Gases within the airgaps 2004 may be relatively still, compared to the flow of respiratory gases within the elongate tube 306. The gases within the airgaps 2004 may be relatively warm, with respect to ambient air. The gases within the airgaps 2004 may, at least in part, thermally insulate one or more of the elongate tube 306 or the flow of respiratory gases within the elongate tube 306 from the ambient air. Which may reduce formation of condensation within the elongate tube 306.

[0460] In some examples, the membrane 2002 may be fixedly attached to the elongate tube 306 by the connectors 302, 304. The connectors 302, 304 may be overmolded, at least in part, to the membrane 2002 and the elongate tube 306.

[0461] In some examples, the membrane 2002 is not otherwise fixedly attached to the permeable elongate tube 306 at all, e.g., intermediate the connectors 302, 304. In other examples, the membrane 2002 may be fixedly attached, e.g., by overmolding, adhesive or welding, to the elongate tube 306 at one, two, three or more discrete locations along the length of the elongate tube 306, e.g., at each outer peak or every other outer peak of the elongate tube 306. Attachment between the membrane 2002 and the elongate tube 306 may inhibit expansion of the membrane 2002 in the radial direction, at least at the attachments. And, to a lesser degree, adjacent or between the attachments.

[0462] The elongate tube 306 and the membrane 2002 may comprise dissimilar materials.

[0463] The elongate tube 306 may be formed, at least in part, from a breathable material as described above, particularly with reference to the example of FIG. 4 and FIG. 5. In some examples, the breathable material of the elongate tube 306 may be different to the breathable material of the membrane 2002. The elongate tube 306 may define the lumen for passage of the flow of respiratory gases.

[0464] In other examples, the elongate tube 306 may be formed, at least in part, from a non-breathable material. In some examples, the elongate tube 306 does not include a breathable material. The elongate tube 306 may instead be porous, e.g., perforated, to provide a path for passage of water molecules from an interior to an exterior of the elongate tube 306, e.g., by the pore-flow mechanism. From there, the water molecules may pass through the breathable material of the membrane 2002 by the solutiondiffusion mechanism. In such examples, the external membrane 2002 may at least in part define the lumen for passage of the flow of respiratory gases.

[0465] In some examples, the membrane 2002 may provide properties similar to the external reinforcement member 502 described above. For example, the membrane 2002 may limit expansion of the permeable elongate tube 306 in the longitudinal direction, in use. The membrane 2002 may be substantially inextensible, e.g., extend by less than about 10% or less than about 5%, when subjected to the forces typically encountered in use.

[0466] In some examples, e.g., where the elongate tube 306 is formed from a non- breathable material, the elongate tube 306 may support the permeable membrane 2002, similarly to the internal reinforcement member 502. The elongate tube 306 may be configured not to expand, in use. Or expand negligibly, e.g., less than 10%, less than 5%, or less than 1%, in one or more of the radial direction or longitudinal direction, in immersion testing. The elongate tube 306 may be relatively rigid when compared to the membrane 2002. Yet flexible enough to allow the expiratory conduit 146 to flex, e.g., drape, under its own weight in the equilibrated state. The elongate tube 306 may impede expansion of the membrane 2002 in the longitudinal direction. The elongate tube 306 may impede expansion of the membrane 2002 in the radial direction. The elongate tube 306 may improve the crush resistance of at least a portion of the membrane 2002.

[0467] In some examples, one or more of the elongate tube 306 or the membrane 2002 may be extruded. In some examples, the elongate tube 306 and the membrane 2002 may be co-extruded.

[0468] FIG. 21 shows a cross-section detail of another example expiratory conduit 146.

[0469] In some examples, as shown in FIG. 21, the membrane 2002 may be an internal membrane 2002. The membrane 2002 may be provided inside the elongate tube 306. The membrane 2002 may form a liner within the elongate tube 306. The membrane 2002 may directly engage, e.g., abut, the elongate tube 306. In some examples, the membrane 2002 may conform, at least in part, to the inner surface of the elongate tube 306, e.g., to inner peaks of a corrugated elongate tube 306, e.g., when the expiratory conduit 146 is in an equilibrated state. In some examples, as shown in FIG. 21, the membrane 2002 may extend substantially directly between the inner peaks of the elongate tube 306, e.g., the membrane may be relatively taut. In other examples, the membrane 2002 may drape between adjacent inner peaks of the elongate tube 306. The membrane 2002 may adopt, at least in part, a corrugation profile of the elongate tube 306.

[0470] Where the membrane 2002 is an internal membrane 2002, the membrane 2002 alone may define the lumen for passage of the flow of respiratory gases. The elongate tube 306 may not be exposed to the flow of respiratory gases at all.

[0471] The elongate tube 306 may be formed from a non-breathable material. The mechanical properties, e.g., one or more stiffness, strength, or crush resistance, of a non-breathable material may not vary, may vary negligibly, or may not vary to the same extent as a breathable elongate tube. The membrane 2002 may not need to constrain the elongate tube 306, as the elongate tube 306 formed from a non-breathable material may not appreciably absorb water. The elongate tube 306 may instead be perforated. The perforations 2102 may provide a path for passage of water molecules from an interior of the elongate tube 306 to ambient air 108, e.g., by the pore-flow mechanism (after passing through the membrane 2002 by the solution-diffusion mechanism).

[0472] The perforations 2102 may be provided through the tube wall at the outer peak and inner trough of the corrugations. Perforations 2102 may be spaced, e.g., equidistantly spaced, about the circumference of the elongate tube 306. In some examples, perforations 2102 may be provided through the tube wall at one or more of the outer trough and inner peak, or at the side walls, of the elongate tube 306. In some examples, the perforations may be between about 20 pm and 2 mm, between about 50 pm and 1.5 mm, or between about 100 pm and 1 mm, in diameter.

[0473] One or more airgaps 2004 may be formed between the membrane 2002 and at least the inner troughs of the elongate tube 306. The airgaps 2004 may fill with air from ambient air, in use. The air within the airgaps 2004 may be relatively still, compared to the flow of respiratory gases within the elongate tube 306. The air within the airgaps 2004 may be relatively warm, with respect to ambient air. And the air within the airgaps 2004 may, at least in part, thermally insulate one or more of the membrane 2002 or the flow of respiratory gases within the membrane 2002 from ambient air. Which may reduce formation of condensation within the membrane 2002.

[0474] The internal membrane 2002 may provide the expiratory conduit 146 with a relatively smooth bore, i.e., a relatively smooth-walled lumen. A smooth bore may provide a relatively low resistance to flow. And may allow condensate or other liquids to drain away from one or more of the patient or the gases source 104, e.g., to a low point of the expiratory conduit. The elongate tube 306 may physically protect the internal membrane 2002, e.g., from one or more of abrasion, cuts, or punctures. The elongate tube 306 may inhibit expansion of the membrane 2002 in the radial direction, e.g., for compliance. But some degree of expansion in the radial direction may be permitted, e.g., for improved breathability. The degree of expansion of the membrane 2002 in the radial direction, in use, may be determined, at least in part, by the corrugation profile of the elongate tube 306, e.g., the depth of the corrugations. In use, expansion of the membrane 2002 in the longitudinal direction and the radial direction, in combination with the positive pressure of the flow of respiratory gases, may cause the membrane 2002 to conform to the inner surface of the elongate tube 306, at least in part, e.g., in a conditioned state or a saturated state.

[0475] Forming a membrane, rather than the thicker elongate tube 306, from the breathable material may have one or more of the benefits of reduced material costs, improved breathability, or faster equilibration or conditioning of the expiratory conduit 146.

Fiber reinforcement

[0476] In some examples, a medical gases conduit may be formed, at least in part, from a composite material. A composite material may combine a matrix material and a reinforcement material. The matrix material and the reinforcement material may provide synergistic properties.

[0477] A composite material may provide improvements in one or more of the mechanical properties, manufacturability, sustainability or breathability of the medical gases conduit. The improved mechanical properties may include one or more of stiffness, strength, crush resistance or pneumatic compliance. The use of a reinforcement material may lead to one or more of the mechanical properties of the medical gases conduit varying less, in use.

[0478] The composite material may be a fiber reinforced polymer (FRP). The composite material may include a polymer matrix and a fiber reinforcement. The polymer matrix may be a breathable material. The breathable material may comprise a block copolymer as previously described. A variety of fillers may be added to the polymer matrix in addition to the fiber reinforcement.

[0479] The fiber reinforcement may include one or more of synthetic fibers or natural fibers. The synthetic fibers may include one or more of carbon fibers, glass fibers or aramid fibers, for example. The natural fibers may include one or more of cellulose fibers, jute fibers, flax fibers or hemp fibers, for example. The use of natural fibers may improve the sustainability of the medical gases conduit. The selection of fiber reinforcement will be dependent on the use case and requirements for the composite material. [0480] The fiber reinforcement may include one or more of continuous fibers or discontinuous fibers.

[0481] In some examples, continuous fibers may span one or more dimensions of the medical gases conduit, e.g., one or more of a length or circumference. In some examples, the discontinuous fibers may have an average length of less than about 25 mm. In some examples, the discontinuous fibers may have an average length of less than about 5 mm.

[0482] In some examples, an average diameter of the fiber reinforcement may be between about 3 pm and 20 pm.

[0483] In some examples, an aspect ratio of the discontinuous fibers, being the ratio between the average diameter of the fiber reinforcement and the average length of the fiber reinforcement, is above a critical fiber length for the polymer matrix. A fiber reinforcement being above a critical fiber length may improve stress transfer between the fiber reinforcement and the matrix material. A fiber reinforcement being above a critical fiber length may improve mechanical properties of the medical gases conduit.

[0484] The fibers may comprise a fiber sizing. The fiber sizing may be used to improve the processability or performance of a fiber reinforcement. The performance of a fiber reinforcement may be improved by increased interfacial adhesion with the polymer matrix. The fiber sizing may be dependent on the polymer matrix material. In some examples, the fiber sizing may comprise an alkoxysilane compound.

[0485] In some examples, the volume fraction of the fiber reinforcement may be between about 5% and 60%, between about 10% and 50%, or between about 20% and 40% of the elongate tube, in one or more of the dry state or the equilibrated state. In one example, the volume fraction of the fiber reinforcement may be about 30% of the elongate tube, in one or more of the dry state or the equilibrated state.

[0486] Continuous fibers may be aligned to span one or more dimensions of the medical gases conduit, e.g., one or more of the length or circumference. In some examples, the continuous fibers may be supplied as a fabric to which the polymer matrix is added to produce the elongate tube. A fabric may comprise a woven, knitted, mat, or braided preform. In some examples, a pultrusion process may be used to combine fiber reinforcement with a polymer matrix.

[0487] In some examples, alignment of the fiber reinforcement may be used to provide orthotropic mechanical properties. In some examples, alignment of the fiber reinforcement within a given direction may increase stiffness and/or strength with respect to forces applied in the given direction. [0488] In some examples, the continuous fibers may be unidirectionally aligned, e.g., in the longitudinal direction. In some examples, at least some, e.g., a majority, of the continuous fibers may extend the full length of the elongate tube 306. In some examples, the continuous fibers may be embedded in the tube wall of the elongate tube. The continuous fibers may follow the corrugation profile of a corrugated elongate tube 306.

[0489] In some examples, different layers of continuous fibers may be aligned in different directions within a laminate, e.g., fibers within a first layer may be aligned in the longitudinal direction (0°) and fibers within a second layer may be aligned in a circumferential direction (90°), and/or fibers in a third layer may be aligned in opposing helical directions (±45°). A laminate may comprise between about 4 and 48 layers. In some examples, a laminate may be quasi-isotropic.

[0490] In some examples, the continuous fibers may be partially embedded in the tube wall of the elongate tube 306. The continuous fibers may be substantially linear. The linear continuous fibers may emerge from the tube wall of a corrugated elongate tube 306, e.g., into the outer trough between adjacent outer peaks.

[0491] The fibers may be uniformly dispersed within the polymer matrix. In other examples, the fibers may be provided at or near one or more of an inner surface or an outer surface of the tube wall.

[0492] Discontinuous fibers may be randomly aligned or aligned in one or more directions. In some examples, the discontinuous fibers may be supplied as a fabric or molding compound to which the polymer matrix is added to produce the medical gases conduit. In some examples, the discontinuous fibers may be compounded as pellets with a matrix material for use in an extrusion process to produce the elongate tube. In some examples, a composite material may comprise more than one matrix material. In some examples a material feedstock may comprise a first pellet comprising a first matrix material and a fiber reinforcement and a second pellet comprising a second matrix material.

[0493] FIG. 22 shows a partial-cutaway of an elongate tube 306. FIG. 23 to FIG. 25 show detailed schematic views of detail A (in FIG. 23 and FIG. 25) and detail B (in FIG. 24) of the elongate tube 306 of FIG. 22, with different discontinuous fibers alignments.

[0494] As shown in the FIG. 23, the fibers may be randomly aligned. A composite material comprising randomly aligned discontinuous fiber reinforcement may provide isotropic properties. In some examples, the fibers may be aligned. In contrast with continuous fiber reinforcement only a percentage of the discontinuous fiber reinforcement may be aligned in a given direction. In some examples, between about 20% and 100% of the fibers may be aligned in a given direction. In some examples, up to about 80% of the fibers may be aligned in a given direction.

[0495] As shown in FIG. 24, the fibers may be aligned in the circumferential direction, following the corrugation profile of the tube wall.

[0496] As shown in FIG. 25, the fibers may be aligned in the longitudinal direction. In some examples, the discontinuous fibers may be randomly aligned as feedstock, e.g., in pellet form, and alignment may be induced during a manufacturing process, e.g., during extrusion into an elongate tube 306.

[0497] A medical gases conduit comprising a material with isotropic properties may be beneficial. In some examples, a composite elongate tube 306 may include randomly aligned discontinuous glass fibers with an average length of at least 0.5 mm, between about 0.5 mm and 10 mm, or between about 1 mm and 5 mm, e.g., about 1.5 mm or about 3 mm. The glass fibers may have an average diameter of between about 5 pm and 30 pm, or between about 10 pm and 20 pm, e.g., about 15 pm. The glass fibers may form between about 5% and 60%, between about 10% and 50%, or between about 20% and 40% of the elongate tube, in one or more of the dry state or the equilibrated state. In some examples a composite elongate tube 206 comprising randomly aligned discontinuous glass fibers may have a higher crush resistance than a medical gases conduit comprising no fiber reinforcement. In some examples a composite elongate tube 306 comprising randomly aligned discontinuous glass fibers may have a lower variation in pneumatic compliance between an equilibrated state and a saturated state than an equivalent medical gases conduit comprising no fiber reinforcement.

Surgical Insufflation System

[0498] A medical gases conduit according to the present disclosure may be applied in any number of alternative medical gases systems. A surgical insufflation system is described below by way of example.

[0499] Referring to FIG. 26, an example surgical insufflation system 2600 is shown in schematic form. The surgical insufflation system 2600 may be configured to supply a flow of insufflation gas to a patient's body cavity, e.g., an abdominal or peritoneal cavity. The flow of insufflation gas may be supplied to the patient's body cavity during a laparoscopic procedure, for example.

[0500] The flow of insufflation gas may be pressurized above atmospheric pressure. The insufflation gas may create a working space within the patient's body cavity while a surgeon or surgical team carries out a surgical procedure, in use. The surgical procedure may involve cauterization creating surgical smoke in the working space. [0501] The insufflation gas may include carbon dioxide. In some examples, the insufflation gas may include a medicament.

[0502] In some examples, the insufflation gas received by the surgical insufflation system 2600 may have a temperature of less than about 25 ⁰ Celsius (°C), less than about 23 °C, less than about 21 °C, or about equal to, or less than, room temperature. In some examples, the insufflation gas received by the surgical insufflation system 2600 may have a relatively humidity of less than about 20%, less than about 10%, or less than about 5%. Heating and humidifying the insufflation gas may decrease cellular damage or desiccation, limit adhesion formation, or reduce other deleterious effects.

[0503] The surgical insufflation system 2600 may include a gases source 2602.

[0504] In some examples, the gases source 2602 may include a wall source 2604 or a compressed gas cylinder 2606. In some examples, the gases source 2602 may include a pressure generator, e.g., a blower, configured to pressurize ambient air. In some examples, gases source 2602, e.g., the pressure generator may be integrated with an insufflator.

[0505] The surgical insufflation system 2600 may include an insufflator supply conduit 2608.

[0506] The insufflator supply conduit 2608 may be configured to receive the flow of insufflation gas from the gases source 2602. The insufflator supply conduit 2608 may be configured to convey the flow of insufflation gas to downstream components of the surgical insufflation system 2600, e.g., an insufflator.

[0507] The insufflator supply conduit 2608 may include a pair of connectors configured to connect the insufflator supply conduit 2608 to one or more other components of the surgical insufflation system 2600, e.g., the gases source 2602 and an insufflator, respectively.

[0508] The insufflator supply conduit 2608 may otherwise be generally similar, e.g., structurally and/or functionally similar, to, e.g., the humidifier supply conduit 116 of the respiratory assistance system 100, as described above.

[0509] The surgical insufflation system 2600 may include an insufflator 2610.

[0510] The insufflator 2610 may be configured to receive the flow of insufflation gas from the insufflator supply conduit 2608. The insufflator 2610 may be configured to control a pressure of the flow of insufflation gas. The insufflator 2610 may be configured to supply the pressure-controlled flow of insufflation gas to downstream components of the surgical insufflation system 2600, e.g., a humidifier supply conduit.

[0511] In some examples, the insufflator 2610 may be configured to supply the flow of insufflation gas at a pressure of between about 5 mm/Hg and 20 mm/Hg. A selected pressure may depend on the size of the patient and the amount of inflation required.

[0512] In some examples, the insufflator 2610 may be configured to supply the flow of insufflation gas at a flow rate of between about 1 L/min and 12 L/min. A selected flow rate may depend on the requirements of the specific operation.

[0513] In some examples, the insufflator 2610 may include a proportional solenoid valve (PSV). The proportional solenoid valve may be operable to control a pressure of the flow of insufflation gas supplied to downstream components of the surgical insufflation system 2600. In other examples, the insufflator 2610 may be integrated with the gases source 2602, e.g., include a pressure generator such as a blower. The pressure generator may be operable to generate the flow of insufflation gas, e.g., by pressurizing ambient air.

[0514] The insufflator 2610 may include one or more sensors, e.g., one or more of a pressure sensor configured to sense a pressure of the flow of insufflation gas or a flow rate sensor configured to sense a flow rate of the flow of insufflation gas.

[0515] The insufflator 2610 may include a user interface. The user interface may be configured to display information to a user. The user interface may include a display, e.g., an LCD or OLED display. The user interface may be configured to receive inputs from a user, e.g., via one or more of a button, switch, dial, or touchscreen display. The inputs may include a desired pressure for the flow of insufflation gas supplied to the patient.

[0516] The insufflator 2610 may include an insufflator controller. The insufflator controller may be configured to control the flow of insufflation gas, e.g., the pressure of the flow of insufflation gas. The insufflator controller may control the proportional solenoid valve or the pressure generator. The insufflator controller may receive inputs from one or more of the sensors or the user interface. The insufflator controller may include one or more processors. The insufflator controller may include a machine- readable medium, e.g., a non-transitory memory. The machine-readable medium may be programmed with instructions which, when executed by the one or more processors, cause the insufflator 2610 to operate as described herein. The insufflator controller may be configured to control the gases source 104 based, at least in part, on inputs received from the user interface. The insufflator controller may be configured to control the insufflator 2610 based, at least in part, on inputs received from the one or more sensors. The insufflator controller may be configured to control the insufflator 2610 using closed- loop control, e.g., using a proportional-integral-derivative (PID) control algorithm.

[0517] The surgical insufflation system 2600 may include a humidifier supply conduit 2612.

[0518] The humidifier supply conduit 2612 may be configured to receive the flow of insufflation gas from the insufflator 2610. The humidifier supply conduit 2612 may be configured to convey the flow of insufflation gas to downstream components of the surgical insufflation system 2600, e.g., a humidifier.

[0519] In other examples, e.g., a surgical insufflation system configured for open surgery, the humidifier supply conduit 2612 may be configured to receive the flow of insufflation gas from a carbon dioxide (CO2) gas supply stand gas outlet port, e.g., directly or via an insufflation gas filter.

[0520] The humidifier supply conduit 2612 may otherwise be generally similar, e.g., structurally and/or functionally similar, to one or more of the humidifier supply conduit 116 of the respiratory assistance system 100 or the insufflator supply conduit 2608 of the surgical insufflation system 2600, as described above.

[0521] The surgical insufflation system 2600 may include a humidifier 2614.

[0522] The humidifier 2614 may be configured to heat and/or humidify the flow of insufflation gas.

[0523] The humidifier 2614 may be configured to receive the flow of insufflation gas from the humidifier supply conduit 2612. The humidifier 2614 may be configured to supply the heated and/or humidified flow of insufflation gas to downstream components of the surgical insufflation system 2600, e.g., a delivery conduit.

[0524] In some examples, the humidifier 2614 may be configured to humidify the flow of insufflation gas to, or near, saturation, e.g., to about 100% relative humidity.

[0525] In one example, the humidifier 2614 may be an F8iP HumiGard™ SH870 Surgical Humidifier available from Fisher 8i Paykel Healthcare Limited of Auckland, New Zealand.

[0526] A funnel may be provided to assist in filling the humidifier, e.g., a humidification chamber, with a humidification liquid, e.g., sterile water.

[0527] The humidifier 2614 may be otherwise be generally similar, e.g., structurally and/or functionally similar, to the humidifier 102 of the respiratory assistance system 100. [0528] In other examples, a surgical insufflation system may omit a humidifier. Or the humidifier 2614 may be disabled. The surgical insufflation system may supply a relatively dry flow of insufflation gas to the patient, e.g., at a relative humidity of below about 80%, below about 60%, or below about 50%.

[0529] The surgical insufflation system 2600 may include a delivery conduit 2616.

[0530] The delivery conduit 2616 may be configured to receive the flow of insufflation gas from the humidifier 2614. The delivery conduit 2616 may be configured to convey the flow of insufflation gas to downstream components of the surgical insufflation system 2600, e.g., a surgical cannula.

[0531] In some examples, the delivery conduit 2616 may be configured to connect to a surgical cannula. The delivery conduit 2616 may include a luer lock connector, e.g., at an outlet end of the delivery conduit 2616. The luer lock connector may be configured to connect directly to the surgical cannula.

[0532] In some examples, e.g., a surgical insufflation system configured for open surgery, the delivery conduit 2616 may be configured to connect to a diffuser.

[0533] The delivery conduit 2616 may otherwise be generally similar, e.g., structurally and/or functionally similar, to one or more of the inspiratory conduit 130 of the respiratory assistance system 100, or the insufflator supply conduit 2608 or humidifier supply conduit 2612 of the surgical insufflation system 2600, as described above.

[0534] The surgical insufflation system 2600 may include a surgical cannula 2618.

[0535] The surgical cannula 2618 may be configured to receive the flow of insufflation gas from the delivery conduit 2616. The surgical cannula 2618 may be configured to connect with the luer lock connector of the delivery conduit 2616. The surgical cannula 2618 may be configured to supply the flow of insufflation gas to the patient's body cavity.

[0536] The surgical cannula 2618 may be configured to receive a surgical instrument, e.g., a scope. A scope 2620 and laparoscopic monitor 2622 are also shown in FIG. 26. The scope 2620 and laparoscopic monitor 2622 may be part of a broader surgical system.

[0537] The surgical insufflation system 2600 may include one or more insufflation gas filters.

[0538] In some examples, an insufflation gas filter may be provided between the insufflator 2610 and the humidifier 2614, e.g., directly between an outlet of the insufflator 2610 and an inlet end of the humidifier supply conduit 2612. In some examples, an insufflation gas filter may be provided between the humidifier 2614 and the surgical cannula 2618, e.g., directly between an outlet of the humidifier 2614 and an inlet end of the delivery conduit 2616.

[0539] The surgical insufflation system 2600 may include a smoke evacuation system 2624.

[0540] The smoke evacuation system 2624 may be configured to receive the flow of insufflation gas and surgical smoke, if any, from the patient's body cavity. In some examples, the smoke evacuation system 2624 may receive the flow of insufflation gas and surgical smoke via the surgical cannula 2618. In other examples, the smoke evacuation system 2624 may receive the flow of insufflation gas and surgical smoke, if any, via a venting cannula. The smoke evacuation system 2624 may be configured to connect to one or more of the surgical cannula 2618 or the venting cannula. The smoke evacuation system 2624 may be configured to convey the flow of insufflation gas and surgical smoke away from the patient.

[0541] The smoke evacuation system may include one or more of a discharge conduit 2626, a discharge filter 2628, or a further discharge conduit 2630.

[0542] The discharge conduit 2626 may be configured to connect to one or more of the surgical cannula 2618 or the venting cannula. The discharge conduit 2626 may be configured to connect to the discharge filter 2628. In some examples, the discharge conduit 2626 may be configured to connect to a vacuum source 2632.

[0543] The discharge filter 2628 may be configured to filter the flow of insufflation gas and surgical smoke, if any, received from the patient's body cavity, e.g., via the discharge conduit 2626. The discharge filter 2628 may include a filter medium. The filter medium may be configured to trap contaminant material in the flow of insufflation gas or the surgical smoke. The contaminant material may include one or more of particulate matter, odors, or gaseous hydrocarbons. In some examples, the filtered flow of insufflation gas downstream from the discharge filter 2628 may be about 100% insufflation gas, e.g., carbon dioxide. In some examples, the discharge filter may remove 99.999% of all particles, cells and viruses. In some examples, the discharge filter may have retention up to 0.02 microns. In some examples, the filtered gas may be vented to ambient air, e.g., remotely from the patient and surgical team.

[0544] The further discharge conduit 2630 may be configured to receive the filtered flow of insufflation gas from the discharge filter 2628. The further discharge conduit 2630 may be configured to convey the flow of insufflation gas away from the patient. The further discharge conduit 2630 may be configured to connect to a vacuum source 2632.

[0545] One or more of the discharge conduit 2626 or further discharge conduit 2630 may otherwise be generally similar, e.g., structurally or functionally similar, to the expiratory conduit 146 of the respiratory assistance system 100. In particular, one or more of the discharge conduit 2626 or further discharge conduit 2630 may be formed at least in part from a breathable material, and may include one or more of a reinforcement member 502, a plurality of retainers 1308, a corrugation profile, a membrane 2002, or a composite material, as described above.

[0546] As the patient's body cavity may already be moist and humid, the flow of insufflation gas may lose little, if any, moisture in the patient's body. And the flow of insufflation gas may become fully saturated, if it is not already saturated before entering the patient's body.

[0547] When the flow of insufflation gas passes out of the patient's body cavity, in use, it may pass along the discharge conduit 2626. The discharge conduit 2626 may be exposed to ambient air. A tube wall of the discharge conduit 2626 may be cooler than the flow of insufflation gas. Condensate may form within the lumen of the discharge conduit 2626. Condensate may alternatively or additionally form within one or more other components of the surgical insufflation system 2600, e.g., the discharge filter 2628 or the further discharge conduit 2630.

[0548] Condensate in the discharge filter 2628 may saturate the discharge filter 2628. The discharge filter 2628 may become at least partially occluded. Occlusion of the discharge filter 2628 may cause an increase in back-pressure. Occlusion of the discharge filter 2628 may hinder dissipation of surgical smoke within the patient's body cavity. Surgical smoke lingering in the patient's body cavity or discharge conduit 2626 may be hazardous to the patient. The vision of a surgeon can be obstructed or hindered due to the lingering surgical smoke. Impeded filtration may result in contaminant material escaping into the operating theatre.

[0549] A discharge conduit 2626 or a further discharge conduit 2630 formed, at least in part, from a breathable material may advantageously mitigate formation of condensate and/or dissipate other liquids within the surgical insufflation system 2600.

[0550] In other examples, the surgical insufflation system 2600 may include a recirculation system, e.g., instead of the smoke evacuation system 2624.

[0551] The recirculation system may be configured to convey the exhausted flow of insufflation gas back to the patient's body cavity. The recirculation system may include one or more of a discharge conduit, discharge filter or further discharge conduit. The further discharge conduit may be coupled to a further surgical cannula. The discharge conduit, discharge filter or further discharge conduit may otherwise be similar to the discharge conduit 2626, discharge filter 2628 or further discharge conduit 2630 of the smoke evacuation system 2624, as described above.

Surgical insufflation circuit

[0552] In the illustrated example, the surgical insufflation system 2600, the humidifier supply conduit 2612, humidification chamber, delivery conduit 2616, discharge conduit 2626, discharge filter 2628 and further discharge conduit 2630 may form a surgical insufflation circuit. More specifically, this particular configuration may form a dual-limb surgical insufflation circuit 2634. The humidifier supply conduit 2612, humidification chamber, and delivery conduit 2616 may be said to form an inlet branch of the duallimb surgical insufflation circuit 2634. The smoke evacuation system 2624 (e.g., discharge conduit 2626, discharge filter 2628, and further discharge conduit 2630) may be said to form an outlet branch of the dual-limb surgical insufflation circuit 2634.

[0553] One or more components of the surgical insufflation circuit 2634 and/or surgical insufflation system 2600 may be packaged and/or sold together as a surgical insufflation circuit kit.

[0554] While various examples have been described above in detail, it is to be understood that one or more features or variants of one example may be combined with the features or variants of one or more other examples. Without limitation:

• the internal reinforcement member 502 of FIG. 5 or FIG. 6 may be combined with any one or more of the: o external reinforcement members 502 of any one of FIG. 8 to FIG. 11, o retainers 1308 of any one of FIG. 13 to FIG. 16, o corrugation profiles of FIG. 17 or FIG. 18, o the membranes 2002 of FIG. 20 or FIG. 21, or o the composite material elongate tubes 306 of FIG. 22 to FIG. 25;

• the external reinforcement members 502 of any one of FIG. 8 to FIG. 11 may be combined with any one or more of the: o internal reinforcement member 502 of FIG. 5 or FIG. 6, o retainers 1308 of any one of FIG. 13 to FIG. 16, o corrugation profiles of FIG. 17 or FIG. 18, o the membranes 2002 of FIG. 20 or FIG. 21, or o the composite material elongate tubes 306 any one of FIG. 22 to FIG. 25;

• the retainers 1308 of any one of FIG. 13 to FIG. 16 may be combined with any one or more of the: o internal reinforcement member 502 of FIG. 5 or FIG. 6, o external reinforcement members 502 of any one of FIG. 8 to FIG. 11, o corrugation profiles of FIG. 17 or FIG. 18, o the membranes 2002 of FIG. 20 or FIG. 21, or o the composite material elongate tubes 306 any one of FIG. 22 to FIG. 25;

• the corrugation profiles of FIG. 17 or FIG. 18 may be combined with any one or more of the: o internal reinforcement member 502 of FIG. 5 or FIG. 6 may be combined with any one or more of the: o external reinforcement members 502 of any one of FIG. 8 to FIG. 11, o retainers 1308 of any one of FIG. 13 to FIG. 16, o the membranes 2002 of FIG. 20 or FIG. 21, or o the composite material elongate tubes 306 of any one of FIG. 22 to FIG. 25;

• the membranes 2002 of FIG. 20 or FIG. 21 may be combined with any one or more of the: o internal reinforcement member 502 of FIG. 5 or FIG. 6 may be combined with any one or more of the: o external reinforcement members 502 of any one of FIG. 8 to FIG. 11, o retainers 1308 of any one of FIG. 13 to FIG. 16, o corrugation profiles of FIG. 17 or FIG. 18, o the composite material elongate tubes 306 of any one of FIG. 22 to FIG. 25; and

• the composite material elongate tubes 306 of any one of FIG. 22 to FIG. 25 may combined with any one or more of the: o internal reinforcement member 502 of FIG. 5 or FIG. 6 may be combined with any one or more of the: o external reinforcement members 502 of any one of FIG. 8 to FIG. 11, o retainers 1308 of any one of FIG. 13 to FIG. 16, o corrugation profiles of FIG. 17 or FIG. 18, o the membranes 2002 of FIG. 20 or FIG. 21.

[0555] Unless the context clearly requires otherwise, throughout the description and claims the words "comprising," "including" and variants are to be construed in an inclusive sense, i.e., "including, but not limited to," rather than an exclusive sense.

[0556] Any reference to publications or products throughout this specification, including the background, should in no way be considered as an admission that the publication or product is necessarily prior art, analogous, widely known or forms part of common general knowledge in the field. GLOSSARY

[0557] "Breathable material" refers to a non-porous permeable material that allows the passage of water molecules through a monolithic wall of the permeable material via the solution-diffusion mechanism, without allowing the bulk passage of liquid water or bulk flow of respiratory gases all the way through the wall. It should be appreciated by one of skill in the art that the water molecules in the wall are molecularly dispersed in the media, and are therefore without a state (solid, liquid, or gas), although they are sometimes referred to in the art as vapor (e.g., the rate of transfer is often referred to as a moisture vapor transmission rate (MVTR) or the like). It should further be appreciated that a monolithic wall does not contain open channels or pores from one major surface to another, such that pathogens could be carried through such channels alongside air or liquid water drops via the pore flow mechanism. However, this definition is not intended to exclude a tube or membrane formed from such a breathable material which may have one or more holes provided through the material, such as might arise from a manufacturing defect for example, which may result in negligible pore flow which does not materially affect the overall performance of the conduit and compliance with the leakage requirements of ISO 5367: 2014. It should yet further be appreciated that, like all polymers, some small molecule transport of respiratory gases (such as oxygen, carbon dioxide, nitrogen or helium) may occur in trace or de minimis amounts (i.e., not "bulk" flow), which, for a breathable material as defined herein, would typically be at a rate at least an order of magnitude lower than that for water molecules. Furthermore, of particular relevance for respiratory gases being delivered to or from a patient, such small molecule transport of respiratory gases would be of an amount less than that allowed for compliance with the relevant standards, for example, in the leakage test of ISO 5367: 2014, which is hereby incorporated by reference in its entirety, at Section 5.4 tested via the method set out in Annex E.

[0558] "Compliance" is defined by ISO standard 4135: 2001, which is hereby incorporated by reference in its entirety, at Section 3.1.5 as the "volume added per unit pressure increase when gas is added to an enclosed space, expressed at the temperature and humidity of that enclosed space at ambient atmospheric pressure" (© ISO 2001). The method for testing compliance of a conduit according to the present disclosure is based upon the method set out in ISO 5367:2014, which is incorporated by reference in its entirety, at Annex H. First, any leaks in the conduit equal to, or greater than, 1 ml/min are sealed (as described in Annex E). Second, the conduit is conditioned at 42 ± 3 °C at not less than 80% relative humidity for at least one hour. Third, one end of the conduit is blocked off and the conduit is placed on a flat surface. Fourth, a pressure measuring device is connected to the opposing end of the conduit. Fifth, the conduit is inflated to a stable gauge pressure of 60 ± 3 cmH₂0 over a period of five seconds or less, and the volume of air required is recorded. It will be appreciated that the conditioning defined by the standard may not reflect in use conditions and the standard was not drafted with breathable materials in mind. To better reflect in use conditions, compliance of a conduit formed at least in part from a breathable material may be further tested by additionally, or alternatively, conditioning the conduit to the simulated conditioned state as described below.

[0559] "Conditioned state" refers to one of a continuum of states in which a conduit or tube has been exposed to a water vapor pressure gradient, with a relatively higher partial pressure of water vapor within the lumen (i.e., higher than the partial pressure of water vapor of the ambient air), for a prolonged period of time. That is, the tube wall has absorbed water molecules from within the lumen, and may be continuing to absorb water molecules from within the lumen. In particular, a conduit which has been, and continues to be, used to convey a humidified flow of respiratory gases for a period of time may be said to be in a conditioned state. The tube wall in the conditioned state will generally contain a higher concentration of water molecules than in the dry state or the equilibrated state. But generally, a lower concentration than in the saturated state. References herein to certain properties of a conduit in "a" (singular) conditioned state are not necessarily intended to apply to all conditioned states, unless otherwise apparent from the context. In particular, depending on design requirements and configuration of the conduit parameters, relative humidity and temperature of the respiratory gases and ambient air, and the concentration of water molecules within the breathable material of the tube, expansion of the tube may or may not be inhibited. That is, there may be subsets of unconstrained conditioned states and constrained conditioned states within the continuum of conditioned states. A conditioned state may be simulated by conditioning the conduit according to the following method. First, an ambient temperature of 22 ± 2° C should be reached and maintained throughout the conditioning method. Second, the conduit is laid in a V-tray in an equilibrated state. Third, the lumen of the conduit is supplied with gases at a flow rate of 10 standard liters per minute (SLPM) (ref 20°C, 101.325kPa), humidified by a humidifier set to a humidity level of 37° C dew point at 100% relative humidity (RH) for a period of 24 hours.

[0560] "Dry state" refers to a state of a conduit, tube, or a sample thereof, which has been dried in accordance with the drying method of ISO 62:2008(E) as briefly described with respect to the second step of the immersion testing method defined below. It is an "artificial" state in that a tube will not generally enter this state during normal use (e.g., in use in an assisted breathing system). The tube wall in the dry state generally contains a lower concentration of water molecules than in any of the equilibrated state, conditioned state and saturated state. [0561] "Equilibrated state" refers to a state in which a conduit or elongate tube, usually free from condensate or other liquids, has been exposed to ambient air, for example in a controlled environment of 40% to 60% relative humidity, both within the lumen and outside the tube wall, for a period of time sufficient for the conduit or tube to reach a steady state. That is, the concentration of water molecules within the breathable material is equilibrated state with ambient air. The tube wall in the equilibrated state will generally contain a higher concentration of water molecules than in the dry state, but generally a lower concentration than in the conditioned state or saturated state. Depending on configuration of the conduit, ambient conditions (including temperature and relative humidity of ambient air), and the concentration of water molecules within the breathable material of the elongate tube, expansion of the tube may or may not be inhibited. In at least some examples, however, the conduit may be designed to allow for at least some expansion of the tube from the equilibrated state before further expansion is inhibited.

[0562] "Immersion testing" refers to a test for determining water absorption based on the ISO 62: 2008(E) standard (© ISO, 2008), which is incorporated herein by reference in its entirety. First, at least three tubular test specimens are cut to a length of 25 ± 1 mm from the tube. The cuts should be made perpendicular to the longitudinal direction of the tube. The cut edges should be smooth and free from cracks. The specimens should include only the active plastic(s) responsible for the water absorption properties, if possible. Heater wires, sleeves, and any mechanical support material should be removed non-destructively, if possible. Second, the specimens are dried. The specimens may be dried in a convection oven or vacuum oven maintained at 50 ± 2 °C for at least 24 hours, or in an industrial dryer at a temperature of 60 °C, dew point of - 40 °C, air flow of 14 cubic meters per hour (m³/h) and drying time of 600 minutes (min). The specimens should be weighed regularly to the nearest 1 mg and returned to the oven/dryer until their mass is constant to within ± 1 mg. Third, the specimens are allowed to cool to room temperature in a desiccator. Fourth, the specimens are weighed (mJ and dimensions measured. Fifth, the specimens are immersed in distilled water for a period of 24 hours. There should be at least 8 ml of distilled water per square centimeter of the total surface are of the specimens, and no less than 300 ml per specimen. If necessary, the specimens may be placed in a stainless-steel wire basket connected to an anchor-weight by a stainless-steel wire. Sixth, the specimens are taken from the water and, using a lint free wipe, surface water is removed. Seventh, the specimens are weighed to the nearest 1 mg within 1 min of removing them from the water. Eighth, steps six (immersion) and seven (weighing) are repeated until the mass of the specimens is constant to within ± 1 mg (m2). Ninth, if the specimens are known or suspected to contain an appreciable amount of water-soluble ingredients, the second step (drying) is repeated, and the samples weighed to correct for water-soluble matter lost during the immersion testing. If the reconditioned mass is less than the conditioned mass, the difference represents the water-soluble matter lost during the immersion testing. The water absorption of each specimen is expressed as the percentage change in mass c relative to the initial mass, according to the equation or, for a specimen containing water-soluble matter, c The result is expressed as the arithmetic mean of

the three (or more) values obtained at the same exposure duration. References to immersion testing in this specification refers to testing of sample specimens of the breathable material or tube alone, in isolation from the connectors or reinforcement member, so that expansion is not inhibited.

[0563] "ISO" refers to the International Organization for Standardization, and more specifically to the international standards defined by the Organization. Those standards are subject to copyright and are available for purchase directly from the International Organization for Standardization at http://www.ISO.org.

[0564] "Leak," "leakage," and "leakage testing" refer to Section 5.4 and the method set out in Annex E of the ISO 5367:2014 standard (© ISO 2014), which is hereby incorporated by reference in its entirety. This standard defines limits for a complete breathing set or a conduit supplied ready for use with a ventilator breathing system (VBS) or anesthetic breathing system of 70 ml/min for an adult patient (intended delivered volume > 300 ml), 40 ml/min for a pediatric patient (50 < 300 ml) or 30 ml/min for a neonatal patient (< 50 ml) at a pressure of 60 ± 3 cmH₂0. For a single conduit not intended for use with a VBS or an anesthetic breathing system, the leakage limit is 25 ml/min at 60 ± 3 cmH₂0. Briefly, leakage is tested according to the standard by first conditioning the conduit at a temperature of 23 ± 3° C for at least an hour. Second, one end of the conduit is closed off. Third, an internal gas pressure of 60 ± 3 cmH₂0 is applied and maintained. Fourth, the flow of air required to maintain that pressure is recorded. It will be appreciated that the conditioning defined by the standard may not reflect in use conditions and the standard was not drafted with breathable materials in mind. To better reflect in use conditions, leakage of a conduit formed at least in part from a breathable material may be further tested by additionally, or alternatively, conditioning the conduit to the simulated conditioned state as described above.

[0565] "Prolonged use," "prolonged period of use," "prolonged period" and the like refers to use of the conduit in a medical gases system, e.g., a respiratory assistance system, conveying heated and humidified medical gases for a continuous period of at least 24 hours. A prolonged period of use may be simulated by the simulated conditioned state described above.

[0566] "Resistance to flow" and "resistance to flow testing" refer to Section 5.5 and the method set out in the ISO 5367:2014 standard (© ISO 2014), the entire content of which is hereby incorporated by reference in its entirety, at Annex F. This standard defines flow resistance limits for a conduit supplied ready to use of 0.06 cmH20/l/min at a flow of 30 l/min for an adult patient (intended delivered volume > 300 ml), 0.12 cmH20/l/min at a flow of 15 l/min for a pediatric patient (50 < 300 ml) and 0.74 cmH20/l/min at a flow of 2.5 l/min. Briefly, resistance to flow is tested by first conditioning the conduit at a temperature of 23 ± 3° C for at least an hour. Second, the flow rate of a flow-controlling device is adjusted and maintained for 30 s and the pressure recorded. Third, the conduit is fitted over the outlet of a buffer reservoir and the free end of the conduit is secured so that the conduit is held straight. Fourth, the air flow is again adjusted and maintained for 30 s and the pressure recorded. Fifth, the increase in pressure due to the conduit is calculated from the difference of the recorded pressures. An increase in flow resistance with bending is tested by first conditioning the conduit at a temperature of 42 ± 3° C and relative humidity of at least 80% for at least one hour. Second, the conduit is suspended over a cylinder of 25 mm diameter and a tensile forces applied to maintain contact over half of the circumference of the cylinder. Third, the air flow is applied, and the pressure recorded after five minutes. Fourth, the increase in pressure due to the conduit is calculated from the difference in pressure for the bent and straight conduits. It will be appreciated that the conditioning defined by the standard does may not reflect in use conditions and the standard was not drafted with breathable materials in mind. To better reflect in use conditions, resistance to flow of a conduit formed at least in part from a breathable material may be further tested by additionally, or alternatively, conditioning the conduit to the simulated conditioned state as described above.

[0567] "Saturated state" refers to a state in which a conduit or tube, or a sample thereof, has been subjected to immersion testing (i.e., submerged in liquid water) for a period of time until the breathable material absorbs no, or negligible, further water molecules. That is, until the combined mass of the breathable material and absorbed water molecules is at or near a maximum. It is an "artificial" state in that a conduit or tube will not generally enter this state during normal use (i.e., in use in a respiratory assistance system). The tube wall in the saturated state generally contains a higher concentration of water molecules than in any of the dry state, equilibrated state or conditioned state. LISTING OF DRAWING ELEMENTS

100 respiratory assistance system

102 humidifier

104 gases source

106 pressure generator

108 ambient air

110 ambient air inlet

112 gases source controller

114 user interface

116 humidifier supply conduit

118 gases source outlet

120 humidification chamber

122 chamber inlet

124 chamber outlet

126 chamber heater

128 humidifier controller

130 inspiratory conduit

132 user interface

134 communications link

136 heater wire

138 sensor probe

140 sensor lead

142 Y-piece

144 patient interface

146 expiratory conduit

148 gases return inlet

150 respiratory breathing circuit

152 inspiratory branch

154 expiratory branch

202 heater base

204 housing

206 cartridge

208 button

210 display

212 indicator light

214 connector

216 connector

218 release button

302 connector 304 connector

306 elongate tube 02 inlet region

404 outlet region

406 intermediate region

408 bulge

502 reinforcement member

504 arrow

702 longitudinal portion

704 radial portion

902 annular member

904 longitudinal member

906 opening

1202 braided sheath

1204 aperture

1302 connector

1304 connector

1306 elongate tube

1308 retainer

1402 clip

1404 opening

1502 ball connector

1504 socket

1602 arm

1702 outer peak

1704 first radius of curvature

1706 outer trough

1708 second radius of curvature

1710 inner peak

1712 third radius of curvature

1714 inner trough

1716 fourth radius of curvature

1718 side wall

2002 membrane

2004 airgap

2102 perforation

2104 elongate tube

2106 airgap

2600 surgical insufflation system

2602 gases source 2604 wall source

2606 compressed gas cylinder

2608 insufflator supply conduit

2610 insufflator

2612 humidifier supply conduit

2614 humidifier

2616 delivery conduit

2618 surgical cannula

2620 scope

2622 laparoscopic monitor

2624 smoke evacuation system

2626 discharge conduit

2628 discharge filter

2630 further discharge conduit

2632 vacuum source

2634 surgical insufflation circuit

Claims

CLAIMS What is claimed is:

1. A medical gases circuit kit for use in conveying a flow of medical gases in a medical gases system, the medical gases system comprising: an inlet conduit; an outlet conduit configured to be fluidly coupled with the inlet conduit, at least a portion of the outlet conduit configured to expand more than the inlet conduit in at least a longitudinal direction, in use; and a plurality of retainers, each of the plurality of retainers configured to retain a portion of the inlet conduit and a portion of the outlet conduit to tether the outlet conduit to the inlet conduit, the plurality of retainers in combination with the inlet conduit configured to inhibit expansion of at least a portion of the outlet conduit in the longitudinal direction, in use.

2. A medical gases circuit kit for use in conveying a flow of medical gases in a medical gases system, the medical gases system comprising: an inlet conduit; an outlet conduit, the outlet conduit comprising a breathable material; and a plurality of retainers, each of the plurality of retainers comprising a pair of retaining members, one of the pair of retaining members configured to receive and retain a portion of the inlet conduit and the other of the pair of retaining members configured to receive and retain a portion of the outlet conduit to tether the outlet conduit to the inlet conduit.

3. The medical gases circuit kit of claim 1 or 2, the plurality of retainers comprising : at least 2 retainers, at least 3 retainers, between 2 and 120 retainers, between 3 and 60 retainers, between 4 and 40 retainers, or one retainer for between every 4 and 50 corrugations of the outlet conduit.

4. The medical gases circuit kit of any one of claims 1 to 3, the plurality of retainers configured to: engage the inlet conduit at a plurality of discrete locations along a length of the inlet conduit, and/or engage the outlet conduit at a plurality of discrete locations along a length of the outlet conduit.

5. The medical gases circuit kit of any one of claims 1 to 4, at least one of the plurality of retainers configured to inhibit expansion of the outlet conduit in a radial direction, in use, by surrounding at least a majority of a circumference of a portion of the outlet conduit.

6. The medical gases circuit kit of any one of claims 1 to 5, wherein absorption of water molecules by the outlet conduit, in use, causes the outlet conduit to expand in a radial direction intermediate a consecutive pair of the plurality of retainers.

7. The medical gases circuit kit of any one of claims 1 to 6, the plurality of retainers each configured to retain respective portions of the inlet conduit and the outlet conduit in a side-by-side relationship.

8. The medical gases circuit kit of claim 7, the plurality of retainers each configured to retain respective portions of the inlet conduit and the outlet conduit substantially adjacent to each other, so that the outlet conduit is, at least in part, heated by the inlet conduit, in use.

9. The medical gases circuit kit of any one of claims 1 to 8, the plurality of retainers each configured to engage one or more of: the inlet conduit so as to inhibit movement along a length of the inlet conduit, and/or the outlet conduit so as to inhibit movement along a length of the outlet conduit.

10. The medical gases circuit kit of any one of claims 1 to 9, the inlet conduit comprising a plurality of corrugations, each of the plurality of retainers configured to engage one or more of the plurality of corrugations of the inlet conduit; and/or the outlet conduit comprising a plurality of corrugations, each of the plurality of retainers configured to engage a one or more of the plurality of corrugations of the outlet conduit.

11. The medical gases circuit kit of any one of claims 1 to 10, the plurality of retainers each comprising: a first clip configured to removably fit about the portion of the inlet conduit; and a second clip configured to removably fit about the portion of the outlet conduit.

12. The medical gases circuit kit of claim 11, wherein: the first clip is part-annular and defines an opening through which the inlet conduit is configured to be removably received, and/or the second clip is part-annular and defines an opening through which the outlet conduit is configured to be removably received.

13. The medical gases circuit kit of any one of claims 1 to 12, one or more of the plurality of retainers configured to be connected with one or more others of the plurality of retainers by a mechanical connection.

14. The medical gases circuit kit of claim 13, the mechanical connection comprising one or more of: a snap-fit connection, a pivotable connection, or a ball-and-socket connection.

15. The medical gases circuit kit of any one of claims 1 to 14, the plurality of retainers each comprising: a first connector; and a second connector, the second connector configured to establish a mechanical connection with the first connector of another of the plurality of retainers.

16. The medical gases circuit kit of claim 15, the plurality of retainers each comprising an arm, and: a distal end of the arm comprising the first connector; and/or a proximal end of the arm comprising the second connector.

17. The medical gases circuit kit of claim 15 or 16, the first connector comprising a ball connector and the second connector comprising a socket, the ball connector configured to establish a ball-and-socket connection with the socket of another of the plurality of retainers, and/or the socket configured to establish a ball-and-socket connection with the ball connector of another of the plurality of retainers.

18. The medical gases circuit kit of any one of claims 1 to 17, wherein each of the plurality of retainers are substantially identical.

19. The medical gases circuit kit of any one of claims 1 to 18, wherein each of the plurality of retainers are integrally formed, e.g., from a polymer material.

20. The medical gases circuit kit of any one of claims 1 to 19, the inlet conduit comprising a heater, e.g., a heating wire.

21. The medical gases circuit kit of any one of claims 1 to 20, the plurality of retainers each configured to: inhibit expansion of the portion of the outlet conduit in a radial direction when the outlet conduit is in one or more of a conditioned state or a saturated state; and/or not inhibit expansion of the portion of the outlet conduit in a radial direction when the outlet conduit is in one or more of a dry state or an equilibrated state.

22. The medical gases circuit kit of any one of claims 1 to 21, the outlet conduit comprising a length, in an equilibrated state, of between about 0.8 m and 2.5 m, and optionally: between about 0.8 m and 1.4 m, or between about 1.0 m and 1.4 m, e.g., about 1.2 m; or between about 1.2 m and 2.0 m, or between about 1.4 m and 1.8 m, e.g., about 1.6 m.

23. The medical gases circuit kit of any one of claims 1 to 22, the medical gases circuit kit not comprising at least one, and optionally both, of: a heater, e.g., a heating wire or a water jacket, configured to be used with the outlet conduit; or a water trap configured to be used with the outlet conduit.

24. The medical gases circuit kit of any one of claims 1 to 23, the outlet conduit comprising an elongate tube, the elongate tube comprising a breathable material which, in use, expands in one or more of a radial direction or the longitudinal direction due to absorption of water molecules.

25. The medical gases circuit kit of claim 24, the breathable material comprising a block copolymer, the block copolymer optionally comprising one or more of: hard segments of polybutylene terephthalate; or soft segments of an ether type macro glycol.

26. The medical gases circuit kit of any one of claims 1 to 25, the outlet conduit comprising an elongate tube, the elongate tube configured to absorb at least 33%, between about 33% and 200%, between about 100% and 160%, between about 120% and 140%, or between about 130% and 135%, e.g., about 133%, of its own mass in water molecules, in immersion testing.

27. The medical gases circuit kit of any one of claims 1 to 26, the outlet conduit comprising an elongate tube, the elongate tube configured to expand by at least 20%, between about 20% and 70%, between about 25% and 50%, or between about 30% and 50% in at least one, and optionally each, of the radial direction or the longitudinal direction, in immersion testing.

28. The medical gases circuit kit of any one of claims 1 to 27, the medical gases circuit kit comprising a respiratory breathing circuit kit, the medical gases system comprising a respiratory assistance system, the inlet conduit comprising an inspiratory conduit, and the outlet conduit comprising an expiratory conduit.

29. The medical gases circuit kit of any one of claims 1 to 28, further comprising any one or more of: a humidifier supply conduit, a pressure relief valve, a humidification chamber, a Y-piece, a catheter mount, a patient interface, a conduit hanger, a filter, or a pressure regulator.

30. The medical gases circuit kit of any one of claims 1 to 27, the medical gases circuit kit comprising an anesthesia breathing circuit kit, the medical gases system comprising an anesthesia breathing system, the inlet conduit comprising an inspiratory conduit, and the outlet conduit comprising an expiratory conduit.

31. The medical gases circuit kit of any one of claims 1 to 27, the medical gases circuit kit comprising a surgical insufflation circuit kit, the medical gases system comprising a surgical insufflation system, the inlet conduit comprising a delivery conduit, and the outlet conduit comprising a discharge conduit.

32. A medical gases conduit for use in conveying a flow of medical gases in a medical gases system, the medical gases conduit comprising: an elongate tube defining a lumen for passage of the flow of medical gases, at least a portion of the elongate tube comprising a breathable material which, in use, is configured to expand due to absorption of water molecules; a pair of connectors provided at respective ends of the elongate tube, the pair of connectors configured for pneumatically coupling the medical gases conduit with other components of the medical gases system; and a reinforcement member configured to engage the elongate tube at least at a plurality of discrete locations along a length of the elongate tube intermediate the pair of connectors, the reinforcement member configured to: impede expansion of at least a portion of the elongate tube in one or more of a radial direction or a longitudinal direction; and/or improve one or more of a crush resistance or a crush recovery of at least a portion of the medical gases conduit.

33. The medical gases conduit of claim 32, wherein the reinforcement member is fixedly attached to the pair of connectors.

34. The medical gases conduit of claim 32 or 33, the reinforcement member located, at least in part, within the lumen of the elongate tube.

35. The medical gases conduit of any one of claims 32 to 34, the reinforcement member comprising a helical shape.

36. The medical gases conduit of any one of claims 32 to 35, the reinforcement member fixedly attached to the elongate tube at one or more locations along the length of the elongate tube intermediate the pair of connectors.

37. The medical gases conduit of any one of claims 32 to 36, the reinforcement member fixedly attached to one or more of the pair of connectors or respective ends of the elongate tube.

38. The medical gases conduit of any one of claims 32 to 37, the reinforcement member configured to: bias the elongate tube to a predetermined length, the predetermined length optionally being about equal to a length of the elongate tube in an equilibrated state, and/or be in tension when the elongate tube is in a conditioned state, in use.

39. The medical gases conduit of any one of claims 32 to 38, the reinforcement member formed, at least in part, from one or more of: a malleable alloy material, and/or a polymer material such as polypropylene.

40. The medical gases conduit of any one of claims 32 to 39, the reinforcement member configured to wick condensate or other liquid within the lumen, in use.

41. The medical gases conduit of any one of claims 32 to 40, the reinforcement member comprising one or more grooves configured to wick the condensate or the other liquid by capillary action, at least in part.

42. The medical gases conduit of any one of claims 32 to 41, the reinforcement member comprising a longitudinal portion and a plurality of radial portions, each of the plurality of radial portions extending outwardly from the longitudinal portion and configured to engage a respective portion of the elongate tube or the pair of connectors.

43. The medical gases conduit of claim 42, the longitudinal portion disposed at or about a center of the lumen.

44. The medical gases conduit of claim 42 or 43, wherein the elongate tube is corrugated and one or more of the plurality of radial portions is configured to engage a respective corrugation of the elongate tube, e.g., with a friction fit or an interference fit.

45. The medical gases conduit of any one of claims 32 to 44, the reinforcement member located, at least in part, outside the elongate tube, e.g., substantially concentrically about the elongate tube.

46. The medical gases conduit of claim 45, the reinforcement member comprising a double helix structure.

47. The medical gases conduit of claim 45 or 46, the reinforcement member comprising an openwork structure.

48. The medical gases conduit of claim 47, the openwork structure formed, at least in part, from an elastomeric material.

49. The medical gases conduit of claim 47 or 48, the openwork structure comprising: a plurality of annular members, the plurality of annular members disposed substantially coaxially and spaced apart along a length of at least a portion of the elongate tube; and a plurality of longitudinal members, the plurality of longitudinal members each extending between respective consecutive pairs of the plurality of annular members.

50. The medical gases conduit of claim 49, wherein the elongate tube is corrugated and one or more of the plurality of annular members are configured to engage a respective corrugation of the elongate tube when the medical gases conduit is in one or more of an equilibrated state or a conditioned state.

51. The medical gases conduit of claim 49 or 50, wherein the plurality of longitudinal members are rotationally offset between two or more consecutive pairs of the plurality of annular members.

52. The medical gases conduit of any one of claims 49 to 51, the openwork structure formed at least in part from one or more of: a polymer material such as polypropylene, and/or a malleable alloy.

53. The medical gases conduit of claim 45, the reinforcement member formed, at least in part, from a shape-memory material.

54. The medical gases conduit of claim 53, wherein the reinforcement member is configured to be deformed by a temperature change of the elongate tube, in use.

55. The medical gases conduit of claim 45, wherein the reinforcement member is malleable.

56. The medical gases conduit of claim 45, the reinforcement member comprising a sheath, wherein the sheath is not braided.

57. The medical gases conduit of claim 56, the sheath configured to conform, at least in part, to an outer surface of the elongate tube when the medical gases conduit is in an equilibrated state.

58. The medical gases conduit of claim 56 or 57, wherein the elongate tube is corrugated, the sheath configured to conform to outer peaks of an outer surface of the elongate tube when the medical gases conduit is in an equilibrated state.

59. The medical gases conduit of claim 32, the reinforcement member embedded within the elongate tube.

60. A medical gases conduit for use in conveying a flow of medical gases in a medical gases system, the medical gases conduit comprising: a membrane, the membrane comprising a breathable material which, in use, is configured to expand due to absorption of water molecules; and an elongate tube, the elongate tube: arranged substantially concentrically with respect to the membrane, fixedly attached to the membrane at a plurality of discrete locations along a length of the elongate tube, configured to support the membrane, configured to be permeable to water molecules, and configured to inhibit expansion of at least a portion of the membrane in at least one of a radial direction or a longitudinal direction, in use.

61. The medical gases conduit of claim 60, the membrane at least in part defining a lumen for the flow of medical gases.

62. The medical gases conduit of claim 60 or 61, wherein the elongate tube is directly attached to the membrane at a plurality of discrete locations along the length of the elongate tube.

63. The medical gases conduit of any one of claims 60 to 62, the medical gases conduit not comprising a rib, e.g., a helical rib, between the membrane and the elongate tube.

64. The medical gases conduit of any one of claims 60 to 63, the elongate tube comprising a corrugated elongate tube.

65. The medical gases conduit of claim 64, wherein the membrane is directly attached to, and spans between, outer peaks outside the corrugated elongate tube or inner peaks within the corrugated elongate tube.

66. The medical gases conduit of any one of claims 60 to 65, the membrane comprising a wall thickness of less than about 200 micrometers (pm), less than about 100 pm, less than about 80 pm, less than about 60 pm, less than about 40 pm, or about 20 pm.

67. The medical gases conduit of any one of claims 60 to 66, the elongate tube arranged substantially concentrically about the membrane.

68. The medical gases conduit of any one of claims 60 to 67, the membrane configured to extend between adjacent inner peaks on an inner surface of the elongate tube.

69. The medical gases conduit of claim 67, the membrane forming a substantially smooth bore of the medical gases conduit.

70. The medical gases conduit of any one of claims 60 to 66, the membrane arranged concentrically about the elongate tube.

71. The medical gases conduit of any one of claims 60-66 or 70, the membrane configured to extend between adjacent outer peaks on an outer surface of the tube.

72. The medical gases conduit of any one of claims 60-66 or 70-71, wherein the elongate tube is porous, e.g., perforated.

73. The medical gases conduit of any one of claims 60 to 72, the membrane and the elongate tube comprising co-extrusions.

74. The medical gases conduit of any one of claims 60 to 73, the membrane and the elongate tube comprising dissimilar materials.

75. A medical gases conduit for use in conveying a flow of medical gases in a medical gases system, the medical gases conduit comprising an elongate tube, the elongate tube at least in part formed from a composite material, the composite material comprising: a polymer matrix, and a reinforcement material.

76. The medical gases conduit of claim 75, the polymer matrix comprising a breathable material.

77. The medical gases conduit of claim 75 or 76, the composite material comprising a fiber reinforced polymer; and/or the reinforcement material comprising a fiber reinforcement.

78. The medical gases conduit of claim 77, the fiber reinforcement comprising one or more of: synthetic fibers, e.g., one or more of carbon fibers, glass fibers, or aramid fibers; or natural fibers, e.g., one or more of cellulose fibers, jute fibers, flax fibers or hemp fibers.

79. The medical gases conduit of claim 77 or 78, a volume fraction of the fiber reinforcement comprising between about 5% and 60%, between about 10% and 50%, between about 20% and 40%, or about 30% of the elongate tube, in one or more of a dry state or an equilibrated state.

80. The medical gases conduit of any one of claims 77 to 79, the fiber reinforcement comprising an average diameter of between about 3 pm and 20 pm.

81. The medical gases conduit of any one of claims 77 to 80, fibers of the fiber reinforcement comprising a fiber sizing.

82. The medical gases conduit of any one of claims 75 to 81, the reinforcement material comprising discontinuous fibers.

83. The medical gases conduit of claim 82, the discontinuous fibers comprising one or more of: an average length of less than about 25 millimeters (mm), or less than about 5 mm; an average length of at least 0.5 mm, between about 0.5 mm and 10 mm, or between about 1 mm and 5 mm, e.g., about 1.5 mm or about 3 mm; an average diameter of between about 5 pm and 30 pirn, or between about 10 pm and 20pm, e.g., about 15 pirn; or an aspect ratio above a critical fiber length for the polymer matrix.

84. The medical gases conduit of claim 82 or 83, wherein: the discontinuous fibers are randomly aligned; the discontinuous fibers are aligned in a circumferential direction; the discontinuous fibers are aligned in a longitudinal direction; or between about 20% and 100%, or up to about 80% of the discontinuous fibers are aligned with each other, e.g., in one of the circumferential direction or the longitudinal direction.

85. The medical gases conduit of any one of claims 75 to 84, the reinforcement material comprising continuous fibers, the continuous fibers optionally spanning one or more of a length or a circumference of the elongate tube.

86. The medical gases conduit of claim 85, the continuous fibers comprising a fabric, e.g., a woven, knitted, mat, or braided preform.

87. The medical gases conduit of claim 85 or 86, wherein the continuous fibers are aligned in one or more directions.

88. The medical gases conduit of any one of claims 85 to 87, wherein the continuous fibers are partially embedded in the elongate tube.

89. A medical gases conduit for use in conveying a flow of medical gases in a medical gases system, the medical gases conduit comprising: an elongate tube defining a lumen for passage of the flow of medical gases; and a pair of connectors provided at respective ends of the elongate tube, the pair of connectors configured for pneumatically coupling the medical gases conduit with other components of the medical gases system, a connector of the pair of connectors comprising a pair of apertures.

90. The medical gases conduit of claim 89, wherein the pair of apertures are diametrically opposed.

91. The medical gases conduit of claim 89 or 90, wherein the pair of apertures, in combination, extend around more than 80% of a circumference of the connector.

92. The medical gases conduit of any one of claims 89 to 91, comprising a sheath provided about an outer surface of the elongate tube.

93. The medical gases conduit of claim 92, the sheath comprising a braided sheath.

94. The medical gases conduit of claim 92 or 93, wherein the sheath is exposed through the pair of apertures.

95. The medical gases conduit of any one of claims 92 to 94, wherein the sheath is fixedly attached to the elongate tube by the connector.

96. The medical gases conduit of any one of claims 92 to 95, wherein the connector is overmolded, at least in part, to the sheath and the elongate tube.

97. The medical gases conduit of any one of claims 89 to 96, wherein the connector is formed in two parts.

98. The medical gases conduit of any one of claims 89 to 97, the connector comprising : a first part which is injection molded, and a second part which is overmolded to the first part.

99. The medical gases conduit of claim 98, wherein the second part is overmolded to the first part, the elongate tube, and a sheath provided about an outer surface of the elongate tube.

100. The medical gases conduit of any one of claims 32 to 99, the medical gases conduit comprising a length, in an equilibrated state, of between about 0.8 meters (m) and 2.5 m, and optionally: between about 0.8 m and 1.4 m, or between about 1.0 m and 1.4 m, e.g., about 1.2 m; or between about 1.2 m and 2.0 m, or between about 1.4 m and 1.8 m, e.g., about

1.6 m.

101. The medical gases conduit of any one of claims 32 to 100, the medical gases conduit not comprising at least one, and optionally both, of: a heater, e.g., a heating wire or water jacket; or a water trap.

102. The medical gases conduit of any one of claims 32 to 101, at least a portion of the medical gases conduit comprising a breathable material which, in use, is configured to expand in one or more of the radial direction, the longitudinal direction, or a wall thickness due to absorption of water molecules.

103. The medical gases conduit of any one of claims 32 to 102, wherein the elongate tube is configured to absorb at least 33%, between about 33% and 200%, between about 100% and 160%, between about 120% and 140%, or between about 130% and 135%, e.g., about 133% of its own mass in water molecules, in immersion testing.

104. The medical gases conduit of any one of claims 32 to 103, wherein the elongate tube is configured to expand by at least 20%, between about 20% and 70%, between about 25% and 50%, or between about 30% and 50% in at least one, and optionally each, of the radial direction or the longitudinal direction, in immersion testing.

105. The medical gases conduit of any one of claims 32 to 104, the breathable material comprising a block copolymer, the block copolymer optionally comprising one or more of: hard segments of polybutylene terephthalate; or soft segments of an ether type macro glycol.

106. The medical gases conduit of any one of claims 32 to 105, the medical gases system comprising a respiratory assistance system, and the medical gases conduit comprising an expiratory conduit configured to convey respiratory gases away from a patient, in use.

107. A medical gases circuit kit comprising the medical gases conduit of any one of claims 32 to 106, and any one or more of: a humidifier supply conduit, a pressure relief valve, a humidification chamber, an inspiratory conduit, a plurality of retaining members, a delivery conduit, a Y-piece, a catheter mount, a patient interface, a conduit hanger, an expiratory conduit, a discharge conduit, a filter, or a pressure regulator.

108. The medical gases conduit of any one of claims 32 to 105, the medical gases system comprising an anesthesia breathing system, and the medical gases conduit comprising an expiratory conduit configured to convey respiratory gases away from a patient, in use.

109. The medical gases conduit of any one of claims 32 to 105, the medical gases system comprising a surgical insufflation system, and the medical gases conduit comprising a discharge conduit configured to convey insufflation gas away from a patient, in use.