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WO2024077360A1 - Canule de drainage de fluide - Google Patents

Canule de drainage de fluide Download PDF

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Publication number
WO2024077360A1
WO2024077360A1 PCT/AU2023/051019 AU2023051019W WO2024077360A1 WO 2024077360 A1 WO2024077360 A1 WO 2024077360A1 AU 2023051019 W AU2023051019 W AU 2023051019W WO 2024077360 A1 WO2024077360 A1 WO 2024077360A1
Authority
WO
WIPO (PCT)
Prior art keywords
tip portion
lumen
fluid drainage
cannula
drainage cannula
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/AU2023/051019
Other languages
English (en)
Inventor
Ashkan VATANI
Shaun Gregory
Sam Liao
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Monash University
Original Assignee
Monash University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from AU2022903021A external-priority patent/AU2022903021A0/en
Application filed by Monash University filed Critical Monash University
Publication of WO2024077360A1 publication Critical patent/WO2024077360A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M25/00—Catheters; Hollow probes
    • A61M25/0021—Catheters; Hollow probes characterised by the form of the tubing
    • A61M25/0023—Catheters; Hollow probes characterised by the form of the tubing by the form of the lumen, e.g. cross-section, variable diameter
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M1/00—Suction or pumping devices for medical purposes; Devices for carrying-off, for treatment of, or for carrying-over, body-liquids; Drainage systems
    • A61M1/36—Other treatment of blood in a by-pass of the natural circulatory system, e.g. temperature adaptation, irradiation ; Extra-corporeal blood circuits
    • A61M1/3621—Extra-corporeal blood circuits
    • A61M1/3653—Interfaces between patient blood circulation and extra-corporal blood circuit
    • A61M1/3659—Cannulae pertaining to extracorporeal circulation
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M1/00—Suction or pumping devices for medical purposes; Devices for carrying-off, for treatment of, or for carrying-over, body-liquids; Drainage systems
    • A61M1/84—Drainage tubes; Aspiration tips
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M25/00—Catheters; Hollow probes
    • A61M25/0009—Making of catheters or other medical or surgical tubes
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M25/00—Catheters; Hollow probes
    • A61M25/0067—Catheters; Hollow probes characterised by the distal end, e.g. tips
    • A61M25/0068—Static characteristics of the catheter tip, e.g. shape, atraumatic tip, curved tip or tip structure
    • A61M25/007—Side holes, e.g. their profiles or arrangements; Provisions to keep side holes unblocked
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M27/00—Drainage appliance for wounds or the like, i.e. wound drains, implanted drains
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M25/00—Catheters; Hollow probes
    • A61M25/0067—Catheters; Hollow probes characterised by the distal end, e.g. tips
    • A61M25/0068—Static characteristics of the catheter tip, e.g. shape, atraumatic tip, curved tip or tip structure
    • A61M2025/0073—Tip designed for influencing the flow or the flow velocity of the fluid, e.g. inserts for twisted or vortex flow
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M27/00—Drainage appliance for wounds or the like, i.e. wound drains, implanted drains
    • A61M27/002—Implant devices for drainage of body fluids from one part of the body to another
    • A61M2027/004—Implant devices for drainage of body fluids from one part of the body to another with at least a part of the circuit outside the body
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M2206/00—Characteristics of a physical parameter; associated device therefor
    • A61M2206/10—Flow characteristics
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M60/00—Blood pumps; Devices for mechanical circulatory actuation; Balloon pumps for circulatory assistance
    • A61M60/30—Medical purposes thereof other than the enhancement of the cardiac output
    • A61M60/36—Medical purposes thereof other than the enhancement of the cardiac output for specific blood treatment; for specific therapy
    • A61M60/37—Haemodialysis, haemofiltration or diafiltration

Definitions

  • the present invention relates to a fluid drainage cannula and its method of manufacture, and in particular to a drainage cannula for use in extracorporeal membrane oxygenation (ECMO), and/or cardio-pulmonary bypass, and/or haemodialysis applications.
  • ECMO extracorporeal membrane oxygenation
  • cardio-pulmonary bypass and/or haemodialysis applications.
  • ECMO veno-arterial extracorporeal membrane oxygenation
  • ECMO circuits are complex systems and thromboemboli may originate within the drainage cannula which may influence the formation of additional thromboemboli downstream in the pump and oxygenator. Probability of thrombosis occurring within the drainage cannula may be influenced by a variety of factors such as material and surface properties, the condition of the blood biochemistry, and the local flow conditions. Insertion of the cannula in the vein can affect the venous flow, which may lead to thrombosis by introducing stagnation zones (low shear) and recirculation zones. At very low shear, coagulation begins by allowing the proteins of the coagulation cascade to produce fibrin and consequently forming a red thrombus.
  • stagnation zones low shear
  • coagulation begins by allowing the proteins of the coagulation cascade to produce fibrin and consequently forming a red thrombus.
  • the applicant has determined that it would be advantageous to provide an improved drainage cannula that is suitable for use in extracorporeal membrane oxygenation, and/or cardiopulmonary bypass, and/or haemodialysis applications.
  • the present invention seeks to at least in part alleviate the problems identified above or to provide the public with a useful choice.
  • a fluid drainage cannula comprising an elongate tubular body having an annular wall which defines an internal lumen, the body extending between a distal end for insertion into a vessel of a subject and a proximal end for connection with an outlet hub; a tip portion of the body located at or about the distal end, the tip portion comprising a length of the body which includes one or more openings, to facilitate the flow of fluids between the vessel and the lumen, wherein the lumen is of non-uniform diameter along at least a portion of the length of the tip portion.
  • the lumen is of varying diameter along the entire length of the tip portion.
  • the lumen of the tip portion is configured such that the diameter of an intermediate segment of the tip portion is less than the diameter of one or both adjacent segment(s) located on either side of the intermediate segment.
  • the lumen of the tip portion is configured, in the longitudinal direction, with a generally parabolic sectional profile in which the smallest diameter of the lumen is located at or about an intermediate segment of the tip portion.
  • the lumen terminates at a tip end of the tip portion and wherein the tip end comprises an opening having a diameter that is the same or smaller than the diameter of the intermediate segment of the tip portion.
  • the lumen terminates at a tip end of the tip portion and wherein the tip end comprises an opening having a diameter that is larger than the diameter of the intermediate segment of the tip portion.
  • the wall at the tip portion of the body is configured to have a thickness that varies between about 0.2 mm and about 2 mm. In a further embodiment, the wall at the tip portion has a maximum thickness of about 1.2 mm.
  • the tip portion comprises a plurality of side openings in the wall to facilitate the flow of fluids between the vessel and the lumen.
  • the plurality of side openings is annularly spaced around the tip portion of the body.
  • the plurality of side openings comprises rows of openings extending along a longitudinal length of the tip portion and/or arranged to be offset from adjacent like-rows of openings.
  • the plurality of the side openings is configured with a diameter of between about 0.5 mm and about 5 mm, and more preferably between about 2 mm and about 3 mm.
  • the plurality of the side openings is configured with diameters varying between about 0.5 mm and about 5 mm, and more preferably between about 2 mm and about 3 mm. In one embodiment, the diameter of the plurality of the side openings varies according to the distance between each said side opening and the distal end.
  • one or more of the plurality of side openings is configured with a diameter that varies along the wall of the body.
  • a distance between each of the plurality of the side openings is between about 1 mm and about 40 mm, and more preferably about 3 mm.
  • the plurality of side openings is configured to be angled from the wall towards the lumen generally in the direction of the proximal end, and preferably angled in a range of between about 15 degrees and about 90 degrees in the direction of the proximal end, and more preferably angled about 30 degrees in the direction of the proximal end.
  • an inlet portion of one or more said plurality of side openings in the wall is configured with a curved sectional profile along a longitudinal direction of the wall.
  • an outlet portion of one or more said plurality of side openings in the wall is configured with a curved sectional profile along a longitudinal direction of the wall.
  • the fluid drainage cannula further comprises an additional elongate tubular body to facilitate flow of fluids therethrough, and wherein the elongate tubular body and the additional elongate tubular body are joined along their respective lengths.
  • the additional elongate tubular body is not provided with side openings along its length and is configured with an internal lumen of uniform diameter.
  • the fluid drainage cannula as described above is used in extracorporeal membrane oxygenation and/or cardio-pulmonary bypass applications with fluid flow rates ranged between about 0.5 and about 8 litres per minute, and more preferably between about 2 and 3 litres per minute.
  • a cannula tip when used with a fluid drainage cannula which comprises an elongate tubular body having an annular wall which defines an internal lumen, the body extending between a distal end for insertion into a vessel of a subject and a proximal end for connection with an outlet hub, the cannula tip comprising: a tip portion of the body located at or about the distal end, the tip portion comprising a length of the body which includes one or more openings to facilitate the flow of fluids between the vessel and the lumen, wherein the lumen is of non-uniform diameter along a substantial length of the tip portion.
  • a method of enhancing flow dynamics of a drainage cannula when used in extracorporeal membrane oxygenation, and/or cardio-pulmonary bypass, and/or haemodialysis applications comprises providing a fluid drainage cannula as described herein, connecting a proximal end of the cannula to an outlet hub and inserting a distal end of the cannula into a vessel of a subject.
  • a method of manufacturing a cannula tip of a fluid drainage cannula as described herein comprising the steps of: casting a volume representing desired fluid passageways of the tip portion, including the lumen (and optionally the side openings), into a solid mould; forming a substrate (such as a soft silicone or similar material) around the solid mould to create an outer mould of the tip portion; casting a volume representing fluid flow only in the lumen of the tip portion into a split solid mould; inserting the split solid mould into the outer mould to form a combined mould; and injecting and setting cannula forming material in the combined mould to form the tip portion of the cannula.
  • a substrate such as a soft silicone or similar material
  • the word “about” or “approximately” when used in relation to a stated reference point for a quality, level, value, number, frequency, percentage, dimension, location, size, amount, weight or length may be understood to indicate that the reference point is capable of variation, and that the term may encompass proximal qualities on either side of the reference point. In some embodiments, the word “about” may indicate that a reference point may vary by as much as 30 percent.
  • the word “substantially” may be used merely to indicate an intention that the term it qualifies should not be read too literally and that the word could mean “sufficiently”, “mostly” or “near enough” for the patentee's purposes.
  • Figure 1 is a schematic view of simplified geometry showing a conventional drainage cannula inserted into the Right Atrium via the Inferior Vena Cava;
  • Figure 2a shows a CFD analysis diagram relating to typical drainage fluid flow characteristics at a tip end of a conventional drainage cannula
  • Figure 2b shows the related analysis chart corresponding to velocity at the tip end of the conventional drainage cannula
  • Figures 3a-3b show a schematic sectional view of a drainage cannula tip portion in accordance with one embodiment of the present invention, along with a perspective view of the fluid flow inside the tip portion;
  • Figures 4a to 8c show cannula tip portion designs in accordance with various embodiments of the present invention, including schematic sectional views of drainage cannula tip portions, schematic sectional views of the fluid flow inside the tip portions, and corresponding CFD analysis diagrams of fluid flow inside the tip portion;
  • Figure 9 shows a CFD analysis diagram of the tip portion of Figure 8c when rotated approximately 90 degrees about a longitudinal axis
  • Figures 10a- 10c show a cannula tip portion design in accordance with a further embodiment of the present invention, including schematic sectional views of drainage cannula tip portion, schematic sectional views of the fluid flow inside the tip portion, and CFD analysis diagram of fluid flow inside the tip portion;
  • Figure 11 is a schematic view of the shape and configuration of a solid mould for manufacturing the tip portion of the drainage cannula
  • Figure 12 is a schematic view of a soft silicone outer mould formed around the solid mould
  • Figure 13 is a schematic view of a split solid mould used with the outer mould for forming a tip portion of the drainage cannula according to an embodiment of the present invention
  • Figure 14 is a schematic sectional view of a drainage cannula tip portion in accordance with another embodiment of the present invention.
  • Figure 15 is a schematic sectional view of a drainage cannula tip portion in accordance with a further embodiment of the present invention, showing a cannula with multiple elongate tube bodies and lumens;
  • Figures 16A and 16B provide experimental data in the form of clot volume charts which show the difference in clot volume comparing the cannula of the present invention and a conventional cannula design.
  • Preferred embodiments of the present invention seek to provide an improved drainage cannula design that reduces the likelihood of stagnant flow formation at recirculation zones proximate the cannula’s side openings.
  • Figures 1 and 2 show the use of a conventional drainage cannula and their typical performance characteristics with respect to fluid flow dynamics inside the cannula.
  • Figure 1 shows one end of a drainage cannula 10 being inserted into a patient such as the Right Atrium 5 via the Inferior Vena Cava 3 in simplified geometric representations of body vessels 1.
  • the drainage cannula can be of any suitable length, with a proximal end 15 connected to an outlet hub (not shown) and a distal end 14, which is inserted into the vessels 1.
  • a tip portion 12 of the cannula 10 is located at the distal end 14 and covers a length of the cannula 10 leading up to the end point of the cannula 10.
  • the tip portion 12 is provided with an opening 17 at the end point, and often along with side openings 16, for draining fluid such as blood from the vessels 1 into the cannula 10, for example as part of a complex assisted circulatory system.
  • FIGS 2a and 2b show a CFD analysis diagram and a corresponding flow velocity chart relating to typical drainage fluid flow characteristics at a tip portion 12 of a conventional drainage cannula.
  • the colour blue in the CFD diagram indicates low fluid velocity while the green, orange and red represents increasing levels of fluid velocity.
  • Conventional drainage cannulas show typical stagnant or relatively lower velocity flows (areas shown in blue) occurring at flow recirculation zones 20 inside the cannula near the side openings 16. It has been observed by the inventors that this stagnation is caused by flow separation at the edges of side openings 16 where sharp changes in the direction of flow occur.
  • the velocity chart shows a significant tapering of fluid flow velocity at areas 22 around side openings 16 closer to the tip end of the cannula and at the centreline of the cannula tip. Higher fluid flow velocity tend to occur at areas 24 closer to the side opening 16 leading into the primary section of the cannula.
  • Embodiments of drainage cannula 10 designs in accordance with the present invention are shown in Figures 3 to 10, 14 and 15, in which partial sections of the cannula 10 corresponding to a length around the distal end 14 of the cannula 10 are shown for each embodiment.
  • This length is referred to as the tip portion 12 of the cannula 10, which comprises an elongate tubular body 11 having an annular tube wall 18 within which an internal lumen 13 for fluid flow is defined.
  • the lumen 13 is to be understood to refer to the internal cavity of the cannula structure having a sectional diameter.
  • the tip portion 12 and the internal lumen 13 of the body 11 terminates at the tip end, in which an opening 17 is provided for fluid flow, and a length of the body 11 having a plurality of side openings 16 provided to facilitate the fluid flow between the vessel 1 and the lumen 13 of the cannula 10.
  • the tip portion 12 of the cannula 10 comprises an altered section of the cannula 10 within which the lumen 13 is of non-uniform or varying diameter.
  • the lumen 13 at an intermediate/middle segment 44 of the section is gradually narrower or of less diameter than the diameter of the lumen 13 at adjacent segments of the section located on either side of the intermediate segment. This can be seen when comparing the diameter of the lumen 13 at regions 32, 31 immediately adjacent the intermediate segment of the lumen 13.
  • the intermediate/middle segment 44 of the present invention as described herein should not be strictly limited to an exact length-wise middle segment of the tip portion 12 of the cannula body 11.
  • the intermediate/middle segment 44 is an area that comprises a section of the lumen 13 of the smallest internal diameter in the tip portion 12 of the cannula body 11. This results in a graduated narrowed passage for fluid flow around the intermediate segment of this section of the lumen 13 and broader passageway for fluid flow at adjacent segments of the lumen 13.
  • an inner surface of the lumen 13 at the section of the tip portion 12 is said to have a generally parabolic sectional profile 34, in the longitudinal direction (when viewing the cannula on its side as seen in the Figure).
  • the altered section of the cannula 10, within which the lumen 13 is of varying diameter or where the inner surface of the lumen 13 has a parabolic profile 34 covers the length of cannula body 11 in which the plurality of side openings 16 are provided. It is to be appreciated that the present invention is not limited to embodiments in which the altered section must cover all side openings 16.
  • the opening 17 of the tip end is configured with a diameter that is larger than the diameter of the intermediate segment 44 of the tip portion 12. In other embodiments, the opening 17 of the tip end is configured with a diameter that is the same or smaller than the diameter of the intermediate segment 44 of the tip portion 12.
  • FIG. 3b A perspective view of the fluid flow 40 through the tip portion 12 of the cannula 10 as configured is shown in Figure 3b, which clearly shows the shape of the fluid flow body in which an intermediate segment 44 of the flow body forms a gradually narrowing passageway connecting to broader passageways 41, 42 before and after the intermediate segment 44.
  • Side flow volumes 46 passing through the side openings 16 are also illustrated in the perspective view.
  • the diameter of the lumen 13 may be altered in a number of ways.
  • the diameter of the lumen 13 in an altered section of the tip portion 12 may be altered by varying the thickness of the annular tube wall 18.
  • Figures 4a to 8c show embodiments of the present invention in which the maximum thickness of the tube wall 18 of the tip portion 12 varies between about 0.9 mm and about 1.5 mm.
  • the embodiment of cannula design as shown in Figure 4a has a maximum tube wall 18 thickness of about 0.9 mm in the altered section of the tip portion 12
  • the cannula design shown in Figure 5a has a maximum tube wall 18 thickness of about 1.2 mm in the same section
  • the cannula design shown in Figure 6a has a maximum tube wall 18 thickness of about 1.5 mm in the same section.
  • the cannula tube wall 18 has a standard thickness of about 0.5 mm. It is to be appreciated that these dimensional values are non-limiting and other tube wall 18 thickness parameters may be equally suitable for creating an effective parabolic sectional profile, including wall thicknesses that range between about 0.2 mm and about 2 mm.
  • the exemplary embodiments provided in the Figures show a gradual change (slope) of tube wall 18 thickness across the altered section of the tip portion 12; however, it is to be appreciated that the magnitude in which the tube wall 18 thickness change across the section is not limited to the ones shown in the examples as other variations in the magnitude of the tube wall 18 thickness change (slope) may also be suitable without departing from the spirit of the invention.
  • Figures 7a to 7c show an embodiment of the drainage cannula having the additional feature in which sections 36, 37 of the lumen 13 leading into, and out of, the altered section described above of the lumen 13 with the parabolic sectional profile 34 (or of varying diameter) have been configured so that the sections 36, 37 form part of the same parabolic sectional profile 34.
  • the parabolic sectional profile 34 of the lumen 13 extends right through to the tip end opening 17 in a smooth curvature 43 so as to allow more gradual changes in the tube wall 18 thickness of the lumen 13 and over a longer length of fluid flow in said altered section of the lumen 13.
  • This feature advantageously reduces abrupt shape changes of fluid flow within the lumen 13, resulting in thinner boundary layers at the sides of the parabolic profile 34 of the lumen 13, and therefore further enhancing the flow dynamics of fluids in the tip portion 12 of the cannula 10.
  • the narrowest section of the lumen 13 has been configured to be substantially at the intermediate/middle segment of the tip portion 12; however, it may be equally suitable for the narrowest section of the lumen 13 to not be substantially located at the intermediate/middle segment of the lumen 13.
  • Dimensional values provided in the embodiments are for reference only and are not limiting on the scope of the invention.
  • the portion of lumen 13 of varying dimeter may in some embodiments span the entire length of the tip portion 12 of the cannula 10.
  • the tip portion 12 of the cannula 10 further comprises a plurality of side openings 16 in the tube wall 18 to facilitate the flow of fluid between the body vessel 1 and the lumen 13.
  • the plurality of side openings 16 may be provided in a number of non-limiting configurations.
  • the plurality of side openings 16 may be annularly spaced around the tip portion 12 of the cannula 10, and may comprise rows of openings 16 extending along the longitudinal length of the tip portion 12 and/or may be arranged to be offset from adjacent like -rows of openings 16. In some configurations, the rows of side openings 16 are spaced 90 degrees apart.
  • the plurality of side openings 16 of the tip portion 12 can be configured with any number of suitable numbers and sizes.
  • the plurality of side openings 16 are configured with the same diameter in the tube wall 18, and the diameter of the openings 16 may be chosen between about 0.5 mm and about 5 mm, and more preferably between about 2 mm and 3 mm.
  • the plurality of side openings 16 on the cannula 10 may have different diameters that vary between about 0.5 mm and about 5 mm, and more preferably between about 2 mm and 3 mm.
  • the diameter of the plurality of the side openings 16 may vary according to the distance between each said side opening 16 and the distal end 14 of the cannula 10.
  • the diameter of side openings 16 in this embodiment may increase or reduce in size, relative to each other, depending on how close each side opening 16 is to the tip end of the cannula 10.
  • the distance between each of the adjacent side openings 16 may range between about 1 mm and 40 mm along the longitudinal length of the cannula 10, and more preferably about 3 mm.
  • the diameter of the side opening may vary along the tube wall 18 of the cannula 10.
  • the diameter of the cavity of the opening 16 may be smaller or larger at one end of the tube wall 18 (closer to the outer surface of the cannula 10) than at an opposing end of the tube wall 18 (closer to the inner surface of the cannula).
  • the side openings 16 may influence fluid flow dynamics inside the tip portion 12 of the lumen 13. Furthermore, the angle in which the side openings 16 are configured in the tube wall 18 relative to the lumen 13 may also influence the fluid flow dynamics inside the lumen 13.
  • the plurality of side openings 16 is configured to be angled towards the lumen 13, from an outer surface of the tube wall 18, generally in the direction of the proximal end 15. More preferable, as seen in the Figures illustrating preferred embodiments, the side openings 16 are angled about 30 degrees from the tube wall 18 towards the lumen 13 in the direction of the proximal end 15.
  • the side openings 16 are angled in a range of between about 15 degrees and about 90 degrees towards the lumen 13 in the direction of the proximal end 15, though it is to be appreciated that other angle variations not specifically described herein may also be suitable for use with the cannula lumen 13 as described in the specification to improve fluid flow dynamics inside the lumen 13.
  • an exemplary embodiment having a continuous section of lumen 13 of parabolic sectional profile through to the tip end opening 17.
  • an inlet 38 and/or outlet 39 portion of one or more of the plurality of side openings 16 in this embodiment are provided with curved configurations which results in curved sectional profiles 48, 49 along the longitudinal direction of the tube wall 18.
  • the curved sectional profiles advantageously reduce pressure drop of fluid flow moving into and out of the side openings 16 by reducing sharp corners or abrupt changes in the direction of fluid flow within the tip portion 12 of the cannula 10. This feature further enhances fluid flow dynamics in the cannula 10 and assists with reducing stagnant flows 22 and recirculation zones 20 in the lumen 13.
  • Figure 9 is a view of the tip portion 12 of Figure 8c when rotated approximately 90 degrees about the longitudinal axis of the tip portion 12 to show an offset row of side openings 16.
  • a variation of this embodiment with arrows showing the primary directions of fluid flow from the patient (distal end 14) to the machine (proximal end 15) is also shown in Figure 14.
  • Figures 10a to 10c illustrate the profiles of a further embodiment of the present invention wherein a partial section of the lumen 13 is provided with a reduced diameter or a parabolic sectional profile. More specifically, the internal surface of the lumen 13 is provided with an initial curvature (for example, a parabolic curve) to reduce the inner diameter around an intermediate section of the cannula before substantially straightening out to result in a small opening 17 (or inner diameter end) with the same or greater wall thickness towards the tip end section 36.
  • the straightening out of the inner surface of the lumen 13 can be flat (substantially uniform diameter) or of a gradual sloping contour.
  • This embodiment advantageously retains a significant portion of the technical merits of the earlier described embodiments while allowing further improvements in manufacturability of the cannula using, for example, a dip moulding process, where a shaped mandrel is dipped into a suitable material and allowed to cure. This process can be repeated until a desired thickness of the wall 18 is achieved.
  • side opening 16 can be added after formation of the cannula tip portion 12 through conventional punching mechanisms.
  • the drainage cannula 10 as described has been configured so that it is particularly effective for use in applications involving high fluid flow rates. Suitable applications including, but not limited to, extracorporeal membrane oxygenation and/or cardiopulmonary bypass applications, and for fluid flow rates ranged between about 0.5 and about 8 litres per minute, and more preferably between about 2 and 3 litres per minute. For haemodialysis applications, the preferable fluid flow rates range between about 0.2 and about 0.4 litres per minute.
  • the present invention may be incorporated in the form of a dual or multi-lumen cannula.
  • Figure 15 illustrates a hybrid cannula having a tubular cannula body 11A with a lumen 13 of non-uniform diameter as described above, and this tubular body 11A is joined with an additional elongate tubular body 11B along their respective lengths, thereby forming a dual-lumen catheter, wherein one lumen is dedicated to blood withdrawal or drainage, and the other lumen is dedicated to blood return or infusion (as indicated by the arrows showing direction of fluid flow).
  • the drainage lumen would benefit from the improvements described herein using the cannula body 11A having a non-uniform diameter lumen 13A, whilst the infusion lumen performs acceptably using a conventionally designed cannula body 11B with a uniform diameter lumen 13B.
  • side openings are not provided in the additional tubular body 1 IB; however, it is to be understood that this example is not to be limiting and that side openings can be provided in some configurations.
  • each respective tubular body 11A, 11B separate the respective lumens 13A, 13B, thereby minimising any impact on fluid movement within the lumens 13 A, 13B of each tubular body 11A, 11B.
  • FIGS. 16A and 16B are clot volume charts from experimental data which show the difference in clot volume comparing the cannula of the present invention and a conventional cannula design. It has been found that the cannula design as described provides advantages over conventional designs including high flow velocity at the tip portion of the cannula around the cannula openings, resulting in fewer clotting formations during use and lower clotting volume.
  • the cannula tip portion 12 of the drainage cannula 10 all as described above may be formed separately and connected to a length of conventional cannula of any suitable length.
  • the cannula tip portion 12 may be integrally formed with any suitable length of cannula body 11 for connection at the proximal end 15 with an outlet hub or device.
  • the proximal end 15 of the drainage cannula 10 is connected to an outlet hub as part of a medical application, and the distal end 14 of the drainage cannula 10, at which the tip portion 12 of the cannula body 11 is located, is inserted into a body vessel of a patient or subject.
  • the unique lumen 13 section of the cannula 10 can be manufactured in a number of suitable ways.
  • One method to manufacture a lumen 13 section in the tip portion 12 of cannula 10 with varying diameters as described above is a three-part moulding process involving customised manufacturing technique.
  • a solid mould 50 made from a metallic material
  • a substrate such as a soft silicone (or suitable soft material) is formed around the solid mould 50 (as it is placed concentrically in a housing) to create an outer mould 52 of the tip portion 12.
  • the outer mould 52 includes the shape and configuration of the side openings 16, and the use of a soft material such as silicone allows the easy removal of the solid mould 50 without causing damage to the soft outer mould 52.
  • a volume representing fluid flow only in the lumen 13 of the tip portion 12 is cast into a two-piece split solid mould so that the mould can be easily extracted in a subsequent forming step.
  • Each of the solid moulds are machined with a smooth finish.

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  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Engineering & Computer Science (AREA)
  • General Health & Medical Sciences (AREA)
  • Anesthesiology (AREA)
  • Biomedical Technology (AREA)
  • Hematology (AREA)
  • Veterinary Medicine (AREA)
  • Animal Behavior & Ethology (AREA)
  • Public Health (AREA)
  • Biophysics (AREA)
  • Pulmonology (AREA)
  • Vascular Medicine (AREA)
  • Cardiology (AREA)
  • Surgery (AREA)
  • Otolaryngology (AREA)
  • External Artificial Organs (AREA)

Abstract

L'invention concerne une canule de drainage de fluide, la canule comprenant un corps tubulaire allongé ayant une paroi annulaire qui définit une lumière interne, le corps s'étendant entre une extrémité distale destinée à être insérée dans un vaisseau d'un sujet et une extrémité proximale destinée à être reliée à une embase de sortie ; une partie pointe du corps située au niveau ou autour de l'extrémité distale, la partie pointe comprenant une longueur du corps qui comprend une ou plusieurs ouvertures pour faciliter l'écoulement de fluides entre le vaisseau et la lumière, la lumière étant de diamètre non uniforme le long d'au moins une partie de la longueur de la partie pointe.
PCT/AU2023/051019 2022-10-14 2023-10-16 Canule de drainage de fluide Ceased WO2024077360A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AU2022903021 2022-10-14
AU2022903021A AU2022903021A0 (en) 2022-10-14 Fluid Drainage Cannula

Publications (1)

Publication Number Publication Date
WO2024077360A1 true WO2024077360A1 (fr) 2024-04-18

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4583968A (en) * 1983-10-03 1986-04-22 Mahurkar Sakharam D Smooth bore double lumen catheter
US20090118661A1 (en) * 2007-11-01 2009-05-07 C. R. Bard, Inc. Catheter assembly including triple lumen tip
US20200188632A1 (en) * 2016-10-05 2020-06-18 Becton, Dickinson And Company Catheter with an asymmetric tip
US20200368499A1 (en) * 2010-05-19 2020-11-26 Nfinium Vascular Technologies, Llc Augmented delivery catheter and method

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4583968A (en) * 1983-10-03 1986-04-22 Mahurkar Sakharam D Smooth bore double lumen catheter
US20090118661A1 (en) * 2007-11-01 2009-05-07 C. R. Bard, Inc. Catheter assembly including triple lumen tip
US20200368499A1 (en) * 2010-05-19 2020-11-26 Nfinium Vascular Technologies, Llc Augmented delivery catheter and method
US20200188632A1 (en) * 2016-10-05 2020-06-18 Becton, Dickinson And Company Catheter with an asymmetric tip

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
GUANG-MAO LIU, HAI-BO CHEN, FU-LIANG LUO, YAN ZHANG, HAN-SONG SUN, JIAN-YE ZHOU, SHENG-SHOU HU: "Numerical Simulation of LVAD Inflow Cannulas with Different Tip", INTERNATIONAL JOURNAL OF CHEMICAL ENGINEERING, HINDAWI PUBLISHING CORPORATION, US, vol. 2012, 1 January 2012 (2012-01-01), US , pages 1 - 8, XP093160755, ISSN: 1687-806X, DOI: 10.1155/2012/596960 *
SAM LIAO, BENJAMIN SIMPSON, MICHAEL NEIDLIN, TIM A. S. KAUFMANN, ZHIYONG LI, MARIA A. WOODRUFF, SHAUN D. GREGORY: "Numerical prediction of thrombus risk in an anatomically dilated left ventricle: the effect of inflow cannula designs", BIOMEDICAL ENGINEERING ONLINE, BIOMED CENTRAL LTD, LONDON, GB, vol. 15, no. S2, 1 December 2016 (2016-12-01), GB , XP093160754, ISSN: 1475-925X, DOI: 10.1186/s12938-016-0262-2 *
VATANI ASHKAN, LIAO SAM, BURRELL AIDAN, CARBERRY JOSIE, AZIMI MARJAN, STEINSEIFER ULRICH, ARENS JUTTA, SORIA JULIO, PELLEGRINO VIN: "Improved Drainage Cannula Design to Reduce Thrombosis in Veno-Arterial Extracorporeal Membrane Oxygenation", ASAIO JOURNAL., LIPPINCOTT WILLIAMS & WILKINS / ASAIO, HAGERSTOWN, MD., US, vol. 68, no. 2, 1 February 2022 (2022-02-01) - 1 February 2022 (2022-02-01), US , pages 205 - 213, XP009554527, ISSN: 1058-2916, DOI: 10.1097/MAT.0000000000001440 *

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