WO2025109031A1

WO2025109031A1 - Positive airway pressure device

Info

Publication number: WO2025109031A1
Application number: PCT/EP2024/083040
Authority: WO
Inventors: Timothy George BAKER; Rebecca Julia SHIPLEY
Original assignee: Meliora Innovation Ltd
Current assignee: Meliora Innovation Ltd
Priority date: 2023-11-20
Filing date: 2024-11-20
Publication date: 2025-05-30
Anticipated expiration: 2026-05-20

Abstract

The present disclosure relates to continuous positive airway pressure (CPAP) devices and methods. The device includes an oxygen flow regulator configured to vary a flow rate of pressurised oxygen and a compressed air flow regulator which varies a flow rate of compressed air. Control elements allow user to control the oxygen flow regulator and the compressed air flow regulator to vary their respective flow rates. The device further includes an outlet connectable to a mask. A demand valve is connected to the outlet and receives pressurised oxygen and compressed air from the oxygen and compressed air flow regulators. The demand valve opens in response to a reduction in pressure at the outlet, caused by inhalation by the patient.

Description

POSITIVE AIRWAY PRESSURE DEVICE

Field of the invention

[0001] The present disclosure relates to a Continuous Positive Airway Pressure (CPAP) device and a method of CPAP treatment.

Background

[0002] Continuous Positive Airway Pressure (CPAP) provides non-invasive respiratory support to a patient, by providing an air-oxygen mix at a constant pressure (greater than atmospheric). CPAP therapy is commonly used to treat patients with respiratory failure due to a wide range of clinical indications such as COPD (chronic obstructive pulmonary disease), heart failure, pneumonia through to respiratory distress syndrome in infants. CPAP is routinely provided in intensive care units, acute admissions units and respiratory wards. Recently, CPAP treatment found extensive use in providing respiratory support to patients during the COVID-19 pandemic. In general, CPAP devices combine a flow generator with a patient circuit that delivers the air flow to the patient via a mask.

[0003] Many existing CPAP devices (i.e., devices capable of delivering the required positive pressure to the airways of the patient) are designed for use in high-resource settings, such as well-equipped hospitals in the developed world. For example, most hospitals in the developed world will have a plentiful supply of medical oxygen (e.g., delivered by piping to the bedside), to which the CPAP device can be connected. The ready supply of oxygen has meant that many existing CPAP devices do not prioritise efficient consumption of oxygen, consuming in the order of 100 L per minute. Often, such devices make use of entrained air which is drawn into the device through an entrainment port by the flow of pressurised oxygen. These designs can result in the leakage of oxygen through the entrainment port. [0004] In lower or middle income (LMI) countries, oxygen provision is less plentiful. Whilst some hospitals may have piped supply, pressurised oxygen stored in cylinders is more common. Provision can be worse in rural areas, with patients often having to travel to get to an oxygen cylinder. If no pressurised oxygen is available, then oxygen concentrators may be used, which typically have an output of around 10 L per minute, a fraction of that needed by many CPAP devices. Typically, a patient needs to breathe 6-10 L of air per minute. Therefore, 6-10 L of oxygen per minute would be sufficient for treating the most severe cases, assuming the CPAP device is able to supply air with with high oxygen concentration and no wastage. However, conventional CPAP devices do not have that capability.

[0005] As well as low oxygen provision in LMI countries, there may also be limitations in terms of available manufacturing machinery and expertise. This may limit the ability to manufacture existing CPAP devices locally, said CPAP devices often including electronic components for control or monitoring, and complex components that require precision manufacture.

[0006] It is an aim of this disclosure to address the above-referenced issues, and any other issues that may be apparent to the skilled reader from the description herein.

Summary

[0007] Bearing in mind the issues set out above, the disclosure provides a CPAP device that is particularly oxygen-efficient, and thus suited for use in circumstances where pressurised oxygen is in limited supply. Furthermore, the disclosed devices may avoid the use of small or complex components and in-built electronics, thus providing devices that are more straightforward to manufacture in LMI countries.

[0008] According to a first aspect of the disclosure, there is provided a continuous positive airway pressure, CPAP, device, comprising: an oxygen flow regulator connectable to a supply of pressurised oxygen and configured to vary a flow rate of the pressurised oxygen therethrough; a compressed air flow regulator connectable to a supply of compressed air and configured to vary a flow rate of the compressed air therethrough; at least one control element configured to control the oxygen flow regulator and the compressed air flow regulator to vary their respective flow rates in response to user input; an outlet connectable via tubing to a mask for placement over airways of a patient, and a demand valve connected to the outlet and comprising an input fluidly coupled to the oxygen flow regulator and the compressed air flow regulator to respectively receive pressurised oxygen and compressed air therefrom; wherein the demand valve is configured to open in response to a reduction in pressure at the outlet caused by inhalation by the patient.

[0009] The oxygen flow regulator may have an aperture of variable size. The control element may be configured to control the flow rate of the oxygen by varying the size of the aperture. The oxygen flow regulator may comprise an oxygen orifice plate comprising a plurality of orifices of different sizes. The orifice plate may comprise a region devoid of an orifice. The orifices, and optionally the region devoid of an orifice, may be selectably disposable on a fluid flowpath through the oxygen flow regulator to vary the size of the aperture. The orifice plate may be rotatable. The control element may be configured to control rotation of the orifice plate.

[0010] The oxygen flow regulator may comprise a sealing valve assembly, configured to seal an inlet of the oxygen flow regulator. The sealing valve assembly may be further configured to open in response to the receipt of the pressurised oxygen. [0011] The compressed air flow regulator may have an aperture of variable size. The control element may be configured to control the flow rate of the compressed air by varying the size of the aperture. The compressed air regulator may comprise a compressed air orifice plate comprising a plurality of orifices of different sizes. The compressed air orifice plate may comprise a region devoid of an orifice. The orifices, and optionally the region devoid of an orifice, may be selectably disposable on a fluid flowpath through the compressed air flow regulator to vary the size of the aperture. The compressed air orifice plate may be rotatable. The control element may be configured to control rotation of the compressed air orifice plate.

[0012] The compressed air flow regulator may comprise a sealing valve assembly, configured to seal an inlet of the compressed air flow regulator. The sealing valve assembly may be further configured to open in response to the receipt of the compressed air.

[0013] The oxygen flow regulator and the compressed air flow regulator may comprise respective sealing valve assemblies respectively configured to seal an inlet of the oxygen flow regulator and an inlet of the compressed air flow regulator, wherein the sealing valve assemblies are further configured to open in response to the receipt of the pressurised oxygen and the compressed air respectively.

[0014] The at least one control element may comprise a thumbwheel. The thumbwheel may comprise an indexing mechanism.

[0015] The at least one control element may comprise a control element configured to control both the oxygen flow regulator and the compressed air regulator. The control element may be configured to increase the flow rate of the pressurised oxygen whilst decreasing the flow rate of the compressed air, and/or vice versa. The control element may be configured to simultaneously rotate respective orifice plates of the oxygen flow regulator and compressed air regulator. Rotation of the orifice plates in a first direction may cause selection of successively smaller apertures of one of the orifice plates, and successively larger orifices of the other of the orifice plates. [0016] The demand valve may be configured to open in response to a reduction in pressure at the outlet compared to ambient pressure. The demand valve may comprise a flexible membrane having a first side exposed to ambient pressure and a second side exposed to pressure at the outlet. The flexible membrane may be configured to deform in response to the reduction in pressure at the outlet, wherein the deformation of the flexible membrane opens the demand valve.

[0017] The device may comprise a relief valve configured to prevent the supply of fluid via the outlet at pressures above a predetermined peak pressure.

[0018] The device may comprise a housing. The housing may comprise the oxygen flow regulator at a first end and the compressed air regulator at a second end opposite the first end. The control element may be disposed between the first end and second end. The demand valve may be disposed on an exterior of the housing. The demand valve may be disposed suitably above the control element on the exterior of the housing. The housing may comprise one or more channels placing the oxygen regulator and/or compressed air regulator in fluid communication with the demand valve. The housing may be cylindrical.

[0019] The device may comprise an oxygen supply connector connectable to a hose to receive the pressurised oxygen therefrom, the oxygen supply connector being in fluid communication with the oxygen regulator to supply the pressurised oxygen thereto.

[0020] The device may comprise a compressed air supply connector connectable to a hose to receive the compressed air therefrom, the compressed air supply connector being in communication with the compressed air regulator to supply the compressed air thereto.

[0021] The device may be free of electronic components. [0022] According to a second aspect of the disclosure, there is provided a kit of parts comprising: the CPAP device of the first aspect; one or more of: an oxygen cylinder storing pressurised oxygen; a compressed air cylinder storing compressed air; an oxygen concentrator; pressurised wall supply of oxygen and compressed air; a mask for placement over the airways of the patient; an oxygen analyser; a positive end expiratory pressure (PEEP) valve; tubing and/or filters for connection between the outlet and the mask.

[0023] In a third aspect of the disclosure, there is provided a continuous positive airway pressure, CPAP, treatment method comprising: receiving pressurised oxygen at an oxygen flow regulator of the CPAP device; receiving compressed air at a compressed air flow regulator of the CPAP device; in response to user input, controlling the oxygen flow regulator and compressed air regulator to vary their respective flow rates; supplying the oxygen and compressed air to a demand valve of the CPAP device, the demand valve coupled to an outlet connected via tubing to a mask placed over airways of a patient; opening the demand valve in response to inhalation of the patient, to supply pressurised oxygen and compressed air to the airways of the patient.

[0024] Further optional features of the method of the third aspect are as defined hereinabove in relation to the first and second aspects, and may be combined in any combination.

Brief of the

[0025] To assist understanding of the present disclosure and to show how embodiments may be put into effect, reference is made by way of example to the accompanying drawings in which:

[0026] Figure 1 is a perspective view of an example CPAP device.

[0027] Figure 2 is a cross-section side view of a first end of the example CPAP device of Figure 1, showing an oxygen regulator.

[0028] Figure 3 is a partial exploded view of an example CPAP device showing an oxygen orifice plate.

[0029] Figure 4 is a second cross-section side view of a second end of the example CPAP device of Figure 1, showing a compressed air regulator.

[0030] Figure 5 is a second partial exploded view of the example CPAP device, showing a compressed air orifice plate.

[0031] Figure 6 is a cross section diagram of a central portion of the example CPAP device.

[0032] Figure 7 is a highly schematic diagram of a system comprising a CPAP device in use for treating a patient.

[0033] Figure 8 is a flowchart of an example method of treating a patient using the CPAP device described herein. [0034] Figure 9 is an exploded view of an example CPAP device, with the housing removed to provide an unobstructed view of the interior.

[0035] Figure 10 is an end-on cross-sectional diagram of the CPAP device, illustrating the demand valve.

[0036] Figure 11 is a cross-section diagram of a complete CPAP device, which is arrived at if Figures 2 and 4 are stitched together at their respective dashed lines.

[0037] In the drawings, corresponding reference characters indicate corresponding components. The skilled person will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various example embodiments.

Detailed Description

[0038] In overview, examples of the disclosure provide a CPAP device that comprises adjustable oxygen and compressed air regulators in fluid communication with a demand valve. The demand valve is configured to open in response to the patient's inhalation, thus supplying oxygen to the patient only when required.

[0039] The term 'CPAP' is used herein to broadly capture the delivery of continuous positive airway pressure to a patient during inhalation. As used herein, the term 'CPAP' need not imply a strictly continuous airway pressure during the entire operation of the device, but rather a substantially continuous airway pressure during inhalation. The term CPAP used herein is explicitly intended to encompass Bi-level Positive Airway Pressure (BPAP) devices, which deliver a first pressure to the patient during inhalation, and deliver a second pressure to the patient as they exhale.

[0040] Figures 1-7 and 9-11 show an example CPAP device 100. The device 100 comprises an oxygen regulator 120, a compressed air regulator 130, and a demand valve 140. In addition, the device 100 comprises a thumbwheel 160 that acts as a control element for controlling the oxygen regulator 120 and compressed air regulator 130.

[0041] The device 100 also comprises a housing 110, which supports the other components of the device 100. The housing 110 is substantially cylindrical, taking the form of a barrel 111c that houses the oxygen regulator 120 at one end 110a and the compressed air regulator 130 at the other end 110b. The demand valve 140 is located on an upper surface 110c of the housing 110, substantially equidistant from the ends 110a, 110b. The thumbwheel 160 is disposed under the demand valve 140 and between the two regulators 120, 130. The axis of rotation of the thumbwheel 160 is substantially coaxial, or at least parallel, with the axis of the barrel 111c of the housing 110, so that the thumbwheel 160 protrudes around the circumference of the barrel 111c.

[0042] The housing 110 also includes conduits, for example formed by drilling in the housing 110, along which fluid may flow between components, as will be discussed in more detail below.

[0043] The device 100 further comprises an oxygen supply connector 121. The oxygen supply connector 121 takes the form of a suitable connector, configured to be coupled to a hose to provide pressurised oxygen to the device 100. In the example shown, the oxygen supply connector 121 generally takes the form of a frustoconical body having a central bore 121a to which oxygen is supplied. The oxygen supply connector 121 is shaped for connection to a hose which fits over the inlet, substantially encapsulating it.

[0044] The oxygen supply connector 121 is in fluid communication with the oxygen regulator, 120. The oxygen regulator 120 is configured to regulate the flow of oxygen into the device 100. The oxygen regulator 120 is adjustable, such that one of a plurality of flow rates can be selected. In conjunction with the compressed air regulator discussed below, this allows the user to select a desired air/oxygen mix. [0045] Figure 2 is a cross-section diagram of one side of an exemplary CPAP device 100. Figure 2 shows a side of the CPAP device 100 comprising an oxygen regulator 120 and the components therein. Figure 2 therefore shows the oxygen regulator 120 in more detail. The regulator 120 comprises a body 122 defining an internal chamber 123. The body 122 comprises two parts. The first part 122a disposed substantially with the housing 110 and secured thereto. The second part 122b is connected to the first part 122a, so that the interior of both parts define the chamber 123. The second part 122b also comprises an inlet 124, which receives oxygen from the oxygen supply connector 121.

[0046] Disposed within the internal chamber 123 is a sealing valve assembly 125, which is biased to a position in which it seals the inlet 124. The sealing valve assembly 125 takes the form of a body comprising a pin portion 126 to occlude the inlet 124. Figure 2 includes an expanded view of the first and second parts 122a, 122b, in which components of the pin portion 126 and the chamber 123 are enlarged for clarity. The pin portion 126 is disposed within a boss 127 formed within the chamber 123 around the inlet 124, and is biased into position by biasing member 128 in the form of a spring. The pin portion 126 comprises an internal channel 126a extending through the interior of the pin portion 126 along its longitudinal axis. Apertures 126b in fluid communication with the channel formed around the exterior of the pin portion 126. The channel 126a has an exit 126c in fluid communication with the interior chamber 123.

[0047] The valve assembly 125 is configured to permit fluid to enter the regulator 120 upon receipt of fluid at a pressure sufficient to overcome the force of the biasing member 128. Particularly, upon receipt of fluid at the sufficient pressure, the valve assembly 125 moves so that the pin portion 126 no longer occludes the inlet 124. This places the apertures 126b in fluid communication with the inlet 124, allowing oxygen to enter the channel 126a. Accordingly, the valve assembly 125 seals the inlet 124 when oxygen is not being supplied. [0048] The regulator 120 further comprises an outlet 129, in fluid communication with a first channel 111 of the housing 110. Disposed between the interior chamber 123 and the outlet 129 is a rotatable orifice plate 166. As can be seen more clearly in Figure 3, which shows an expanded view of the oxygen regulator 120 and the orifice plate 166, the orifice plate 166 comprises a plurality of orifices 166a formed therethrough, each orifice 166a being of a different size. The orifices 166a can be selectively brought into position in front of the outlet 129 (which is not shown in Figure 3 for clarity). Each different size orifice 166a limits the flow of oxygen from the outlet 129 into the first channel 111 by a different extent. The orifice plate 166 also comprises a region 166b devoid of an orifice, which can be rotated into position to occlude the outlet 129. Accordingly, the orifice plate 166 provides a mechanism for varying the size of an aperture in the regulator through which the fluid passes.

[0049] The orifice plate 166 is coupled to the thumbwheel 160, such that rotation of the thumbwheel 160 causes rotation of the orifice plate 166. Particularly, the orifice plate 166 is mounted on one end of a stem 161 extending into the first part 122a and into the chamber 123.

[0050] The device 110 further comprises a compressed air connector 131 and associated compressed air regulator 130. The compressed air connector 131 and regulator 130 have the same structure as the corresponding oxygen components 121, 120. These components only differ in use, in that they are intended to receive compressed air. Accordingly, corresponding components have the same reference numerals as the components of the oxygen regulator 121, incremented by 10, as shown in Figure 4. Note that Figure 4 is a cross-section diagram of a second half of the exemplary CPAP device of Figure 2. The entire device 100 is further illustrated in crosssection in Figure 11.

[0051] The compressed air regulator 130 has its outlet 139 connected to a second channel 112 of the housing. Like oxygen regulator 120, the orifice plate 176 of the regulator 130 is coupled to the thumbwheel 160, such that rotation of the thumbwheel causes rotation of the orifice plate 166. A second stem 162 supports the plate 138 in a manner corresponding to stem 161.

[0052] Notably, the two orifice plates 166, 176 may be arranged so that rotation of the thumbwheel 160 in a given direction causes the selection of successively smaller apertures of one orifice plate, and successively larger orifices of the other orifice plate. When one orifice plate (e.g. 166) has its largest orifice in front of its respective outlet, the other orifice plate (e.g., 176) may have the region devoid of an orifice in front of its respective outlet. Accordingly, rotation of the thumbwheel 160 causes variation in the mixture of oxygen and air, from 100% oxygen to 100% compressed air.

[0053] Turning now to the thumbwheel 160 itself in more detail, the thumbwheel 160 is located in a cavity 113 formed in the housing 110 between the two regulators 120, 130. The stems 161, 162 extending into the respective regulators 120, 130 form an axle about which the thumbwheel 160 rotates.

[0054] As can be best seen in Figure 5, the thumbwheel 160 includes an indexing or ratcheting mechanism 163. The indexing mechanism 163 comprises a series of circular detents 163a formed at regular intervals in a circular pattern around the axle, and two engaging elements 163b having ball-shaped ends biased into the detents 163a. Accordingly, the thumbwheel 160 indexes into the positions defined by the detents 163a. The positions correspond to locations in which orifices of the orifice plates 166, 176 are positioned in over their respective outlets.

[0055] Returning to the housing 110, with reference now to Figure 6, the first channel 111 and second channel 112 meet at a junction 114. A third channel 113 extends from the junction to an input 141 of the demand valve 140. Accordingly, the input 141 of the demand valve is in fluid communication with the outlets 129, 139 of both regulators 120, 130.

[0056] The demand valve 140 is connected to an outlet 142, which is connectable to a mask (200, see Figure 7) for placement over the airways of a patient 300. For example, suitable tubing and filters 210 may be connected between the outlet 142 and mask 200. The demand valve 140 is configured to open, and thus deliver fluid at positive pressure, in response to a reduction in pressure at the outlet 142.

[0057] In more detail, with reference again to Figure 6, the demand valve 140 comprises a flexible membrane 143. The flexible membrane 143 is formed on the exterior of the device 100, such that its exterior 143c is exposed to ambient pressure. The other side 143b of the membrane 143 is exposed to the pressure within the valve 140. The membrane 143 has a non-flexible element 143a formed therein, which may for example form a circular land in the middle of the substantially annular membrane 143. The membrane 143 is configured to flex downward in response to pressure in the valve 140 being lower than ambient pressure. Upon flexing inward, the non- flexible element 143a is configured to push downwards onto actuator element 144. The downward motion of the actuator element 144 is configured to open valve element 145 of the valve 140, and thus allow fluid to exit via outlet 142. For example, valve element 145 may be rotated by a linkage connected actuator element 144 to the valve element 145. Reference is also made to Figure 10, which shows a cross section of the demand valve 140 of the exemplary CPAP device 100. Figure 10 shows the CPAP device 100 viewed from an end-on perspective with respect to Figure 1, i.e., along an axis extending through the oxygen supply connector and compressed air supply connector. Figure 10 shows the demand valve 140 comprising the flexible membrane 143, non-flexible element 143a of the membrane, actuator element 144, and valve element 145. The thumbwheel 160 and body 110 of the CPAP device 100 are also shown for reference.

[0058] In another example, not illustrated, the device 100 can further include a relief valve. The relief valve acts to prevent the supply of fluid via the outlet 142 at pressures above a predetermined peak pressure. The pressure may for example be 10 cm of water. The relief valve may be incorporated into the demand valve 140, or disposed on the fluid flowpath after the demand valve 140.

[0059] Reference is now made to Figure 9, which shows an exploded view of the CPAP device and the components therein. For clarity, not all components described herein are shown in Figure 9 and some substructures which are shown, such as the demand valve, are shown intact as opposed to being separated into individual components.

[0060] From left to right of the drawing, Figure 9 shows an oxygen supply connector 121, a second part of the oxygen regulator 122b, a biasing means 128 in the form of a spring, a sealing valve assembly, a first part of the oxygen regulator 122a, an orifice plate 166, an indexing mechanism 163, a thumb wheel 160, a demand valve 140, a second orifice plate 176, a first part of the compressed air supply regulator 132a, a second part of the compressed air regulator 132b, and a compressed air supply connector 131.

[0061] Turning now to Figure 7, a system 1 including the CPAP device 100 is illustrated. As shown, the CPAP device 100 is connected to a supply of compressed air 220 and a supply of pressurised oxygen 230. These may for example take the form of cylinders containing the pressurised gas, oxygen concentrators, or supplies of the sort readily available in many hospitals (e.g. pressurised wall supplies). The CPAP device 100 is also connected to a mask 200 via tubing 210. One or more filters may also be disposed on the fluid flowpath between the CPAP device 100 and the mask 200. Although not illustrated, the system 1 may include an oxygen analyser and/or a positive end expiratory pressure (PEEP) valve.

[0062] In use, the CPAP device 100 is connected as shown in Figure 7. A user rotates the thumbwheel 160 to select a desired mixture of oxygen and compressed air. Upon inhalation by the patient, the pressure inside demand valve 140 drops below ambient pressure, causing the membrane 143 to flex. The membrane 143 (particularly part 143a) in turn contacts the actuator element 144, opening demand valve and supplying the mixture of oxygen and compressed air to the patient. As the patient exhales, the membrane 143 returns to the position shown in the figures, thus closing the valve 140. Consequently, the patient is only provided with pressurised oxygen and/or compressed air upon inhalation. [0063] Figure 8 shows a method of treatment. The method is a continuous positive airway pressure, CPAP, treatment method, which includes a first step S801 in which pressurised oxygen is received at an oxygen flow regulator of a CPAP device.

[0064] At a next step S803, compressed air is received at a compressed air flow regulator of the CPAP device.

[0065] In response to user input, the oxygen flow regulator and compressed air regulator are controlled to vary their respective flow rates at a step S805.

[0066] In a next step, S807, the oxygen and compressed air are supplied to a demand valve of the CPAP device, wherein the demand valve is coupled to an outlet connected via tubing to a mask placed over airways of a patient.

[0067] Finally, in a step S809, the demand valve is opened in response to inhalation of the patient, to supply pressurised oxygen and compressed air to the airways of the patient.

[0068] Further steps may be included in the method, as described herein. The CPAP device referred to in the above CPAP treatment method may be a CPAP device according to any of the embodiments described herein.

[0069] Various modifications and alterations may be made to the examples described above, within the scope of the disclosure.

[0070] Although particular types of regulator valves and demand valves have been illustrated, the disclosure is not limited to these valve constructions. Any valves capable of acting as regulators to proportionally mix oxygen and air supply may be used. For example, regulator valves with tapered cones that can be adjusted to regulate fluid flow may be employed. That said, the use of orifice plates has been found to provide an acceptable, easy to manufacture and low complexity solution which is suitable for use in many circumstances where high-precision mixing of oxygen and air is not required. Likewise, any valve capable of acting as a demand valve so as to open in response to inhalation may be used. [0071] Although a thumbwheel is shown as an example of a control element, it will be understood that other control elements may be employed, including switches, sliders, wheels other than thumbwheels and the like. Furthermore, although a thumbwheel is shown that controls both regulators simultaneously, in other examples separate thumbwheels or other control elements may be provided that independently control each regulator. Although the housing shown is substantially cylindrical, other shapes and configurations are possible. Furthermore, the housing need not be a unitary body - the device could be provided in a plurality of housings connected by suitable tubing.

[0072] Advantageously, the examples described herein provide a device that is resource efficient, in that it supplies fluid at positive pressure to the patient on demand rather than constantly. The inventors have found that demand valves, which are used in breathing apparatuses very close to the face in other applications (e.g., incorporated into masks), can be disposed remotely from the face and act to reduce oxygen consumption. Furthermore, the examples described herein use a source of compressed air, rather than relying on entrainment, which further reduces oxygen consumption.

[0073] Furthermore, the examples herein provide a device that advantageously can be manufactured in low-resource environments. The device is free of electronic components, and the mechanical components do not require specialist or precision manufacturing techniques to fabricate.

[0074] Throughout the defined aspects, detailed description and claims, the references to CPAP may be replaced with BPAP. That is to say, in any aspect or embodiment herein, the device may be referred to as a BPAP device. Similarly, in any aspect or embodiment herein, the device may be simply referred to as a positive airway pressure (PAP) device. That is to say, whilst the term CPAP has been used to refer to the device, it will be apparent to the skilled person understanding the functions and features of the described embodiments that they are capable of providing a first pressure during an inhalation phase (i.e. in response to opening of the demand valve) and a second pressure at other times. Put differently, it will be apparent to the skilled person reading the disclosure herein that the term CPAP may not be used to refer to a traditional CPAP device that applies positive pressure over a full breathing cycle.

[0075] The examples described herein are to be understood as illustrative examples of embodiments of the invention. Further embodiments and examples are envisaged.

[0076] Any feature described in relation to any one example or embodiment may be used alone or in combination with other features. In addition, any feature described in relation to any one example or embodiment may also be used in combination with one or more features of any other of the examples or embodiments, or any combination of any other of the examples or embodiments. Furthermore, equivalents and modifications not described herein may also be employed within the scope of the invention, which is defined in the claims and/or summary section.

Claims

1. A continuous positive airway pressure, CPAP, device, comprising: an oxygen flow regulator connectable to a supply of pressurised oxygen and configured to vary a flow rate of the pressurised oxygen therethrough; a compressed air flow regulator connectable to a supply of compressed air and configured to vary a flow rate of the compressed air therethrough; at least one control element configured to control the oxygen flow regulator and the compressed air flow regulator to vary their respective flow rates in response to user input; an outlet connectable via tubing to a mask for placement over airways of a patient, and a demand valve connected to the outlet and comprising an input fluidly coupled to the oxygen flow regulator and the compressed air flow regulator to respectively receive pressurised oxygen and compressed air therefrom, wherein the demand valve is configured to open in response to a reduction in pressure at the outlet caused by inhalation by the patient.

2. The CPAP device of claim 1, wherein the oxygen flow regulator comprises an aperture of variable size, and wherein the control element is configured to control the flow rate of the oxygen flow rate by varying the size of the aperture.

3. The CPAP device of claim 2, wherein the oxygen flow regulator comprises an oxygen orifice plate comprising a plurality of orifices of different sizes.

4. The CPAP device of claim 3, wherein the orifice plate comprises a region devoid of an orifice.

5. The CPAP device of any preceding claim, wherein the oxygen flow regulator and/or the compressed air flow regulator comprise respective sealing valve assemblies respectively configured to seal an inlet of the oxygen flow regulator and an inlet of the compressed air flow regulator, wherein the sealing valve assemblies are further configured to open in response to the receipt of the pressurised oxygen and the compressed air respectively.

6. The CPAP device of any preceding claim, wherein the compressed air flow regulator comprises an aperture of variable size, and wherein the control element is configured to control the flow rate of the compressed air flow by varying the size of the aperture.

7. The CPAP device of claim 6, wherein the compressed air regulator comprises a compressed air orifice plate comprising a plurality of orifices of different sizes.

8. The CPAP device of claim 7, wherein the compressed air orifice plate comprises a region devoid of an orifice.

9. The CPAP device of claim 7 or 8, wherein the compressed air orifice plate is rotatable, and wherein the at least one control element is configured to control rotation of the compressed air orifice plate.

10. The CPAP device of any preceding claim, wherein the at least one control element comprises a thumbwheel.

11. The CPAP device of claim 10, wherein the thumbwheel comprises an indexing mechanism.

12. The CPAP device of any preceding claim, wherein the at least one control element comprises a control element configured to control both the oxygen flow regulator and the compressed air regulator.

13. The CPAP device of claim 12 when dependent on claims 3 and 7, wherein the control element is configured to simultaneously rotate respective orifice plates of the oxygen flow regulator and compressed air regulator, and wherein rotation of the orifice plates in a first direction causes selection of successively smaller apertures of one of the orifice plates, and successively larger orifices of the other of the orifice plates.

14. The CPAP device of any preceding claim, wherein the demand valve is configured to open in response to a reduction in pressure at the outlet compared to ambient pressure.

15. The CPAP device of claim 14, wherein the demand valve comprises a flexible membrane having a first side exposed to ambient pressure and a second side exposed to pressure at the outlet, and wherein the flexible membrane is configured to deform in response to the reduction in pressure at the outlet, the deformation of the flexible membrane opening the demand valve.

16. The CPAP device of any preceding claim, further comprising a relief valve configured to prevent the supply of fluid via the outlet at pressures above a predetermined peak pressure.

17. The CPAP device of any preceding claim, further comprising a housing, the housing comprising the oxygen flow regulator at a first end and the compressed air regulator at a second end opposite the first end; wherein the control element is disposed between the first end and second end of the housing, and the demand valve is disposed on an exterior of the housing; and wherein the housing further comprises one or more channels placing the oxygen regulator and/or compressed air regulator in fluid communication with the demand valve.

18. The CPAP device of any preceding claim, further comprising an oxygen supply connector connectable to a hose to receive the pressurised oxygen therefrom, the oxygen supply connector being in fluid communication with the oxygen regulator to supply the pressurised oxygen thereto; and/or a compressed air supply connector connectable to a hose to receive the compressed air therefrom, the compressed air supply connector being in communication with the compressed air regulator to supply the compressed air thereto.

19. The CPAP device of any preceding claim, wherein the device is free of electronic components.

20. A kit of parts comprising: a CPAP device according to any of claims 1-19; and one or more of: an oxygen cylinder storing pressurised oxygen; a compressed air cylinder storing compressed air; an oxygen concentrator; a mask for placement over the airways of the patient; tubing and/or filters for connection between the outlet and the mask.

21. A continuous positive airway pressure, CPAP, treatment method comprising: receiving pressurised oxygen at an oxygen flow regulator of a CPAP device; receiving compressed air at a compressed air flow regulator of the CPAP device; in response to user input, controlling the oxygen flow regulator and compressed air regulator to vary their respective flow rates; supplying the oxygen and compressed air to a demand valve of the CPAP device, the demand valve coupled to an outlet connected via tubing to a mask placed over airways of a patient; and opening the demand valve in response to inhalation of the patient, to supply pressurised oxygen and compressed air to the airways of the patient.