WO2016097669A1

WO2016097669A1 - Entrainment devices and respiratory therapy devices

Info

Publication number: WO2016097669A1
Application number: PCT/GB2015/000297
Authority: WO
Inventors: Anthony Lucio BELISARIO; Paul James Leslie Bennett; Robert James Burchell; Mohammad Qassim Mohammad KHASAWNEH; Mark Charles Oliver
Original assignee: Smiths Medical International Limited
Priority date: 2014-12-19
Filing date: 2015-11-10
Publication date: 2016-06-23

Abstract

A respiratory therapy air entrainment device (1) has an oxygen jet nozzle (15) mounted at the open, upstream end of an outer housing (10) in axial alignment with the entrance of a diffuser sleeve (30). The diffuser sleeve (30) has a tapered bore (38) along its length and is mounted in the housing (10) by cooperating screw threads (33 and 34) on the outside of the diffuser sleeve and on the inside of the housing. The diffuser sleeve (30) can be screwed towards or away from the jet nozzle (15) by means of a ring (35) on the diffuser sleeve so as to' alter the effective size of the diffuser sleeve and hence the amount of air entrained by the device.

Description

ENTRAINMENT DEVICES AND RESPIRATORY THERAPY DEVICES

This invention relates to entrainyhent devices of the kind including a gas jet outlet aligned axially with an entrance to a diffuser member.

Entrainment devices are used to mix different gases. In respiratory therapy devices pressurised oxygen may be supplied to an entrainment device to draw air through the device and to mix it with the oxygen. Entrainment devices are also used in other applications, such as to mix fuel vapour with gases in combustion engines.

Patients suffering from respiratory ailments such as asthma or COPD may be treated with a respiratory therapy device incorporating a continuous positive air pressure (CPAP) or a bi-level positive pressure therapy function. This can be achieved using a demand valve that provides a pressure above atmosphere to the patient only when he breathes in. Alternatively, an air entrainment device run from a pressurised source of oxygen, such as a low-flow oxygen therapy line, may be used to entrain air from the atmosphere to deliver a continuous mix of air and oxygen above atmospheric pressure to the patient. Both arrangements extend the alveoli in the lungs thereby improving gaseous exchange and blood saturation without the need for the patient to extend his thoracic muscles as much on each breath.

Devices that deliver oxygen via a demand valve do this only during the inspiratory phase and thereby conserve the use of oxygen. Devices that deliver a gas mix continuously use oxygen continuously but this typically only makes up about one third of the gas mix whilst giving a total concentration of oxygen in the mix of about 50%. This also helps conserve the oxygen, which is particularly important where this is obtained from an oxygen cylinder.

Although the increased concentration of oxygen may be beneficial to the patient, the primary mechanism that achieves the therapy is the elevated pressure from the CPAP or bi- level positive pressure. Current entrainment devices have an oxygen jet with a fixed size orifice and a fixed size diffuser. This means that the jet flow is restricted to a set value at a particular pressure. Increasing the size of the diffuser entrains more air but it also has the effect of reducing the concentration of oxygen in the mix and makes it more difficult to overcome higher patient back pressures.

It is an object of the present invention to provide an alternative entrainment device and an alternative respiratory therapy device including an entrainment device.

According to one aspect of the present invention there is provided an entrainment device of the above-specified kind, characterised in that the entrainment device has an adjustable mounting arrangement by which the axial spacing between the gas jet outlet and the diffuser member can be adjusted, and that the diffuser member has an internal width that varies along a part at least of its length such that the effective size of the diffuser member can be varied by adjusting the axial spacing between the gas jet outlet and the diffuser member.

According to another aspect of the present invention there is provided respiratory therapy entrainment device including a patient inlet, an air inlet open to receive atmospheric air, and a source of pressurised oxygen, the entrainment device including an oxygen jet outlet connected with the source of pressurised oxygen, and a diffuser member having an inlet entrance in communication with the air inlet, the oxygen jet outlet being aligned with the entrance to the diffuser member so as to entrain air within the diffuser member, characterised in that the therapy entrainment device has an adjustable mounting arrangement by which the axial spacing between the oxygen jet outlet and the diffuser member can be adjusted, and that the diffuser member has an internal width that varies along a part at least of its length such that the effective size pf the diffuser member can be varied by adjusting the axial spacing between the oxygen jet outlet and the diffuser member so as thereby to alter the concentration of oxygen in the entrained gas mixture supplied to the patient inlet.

The adjustable mounting arrangement preferably includes a screw thread mechanism such that the axial spacing of the diffusor member from the jet outlet can be adjusted by rotating the diffuser member relative to its mounting. The surface of the interior of the diffuser member may be provided with a texture to increase turbulence. The texture may be provided by one or more of the following: surface roughness, concentric rings, steps or striations. The jet outlet may include an arrangement for adjusting gas flow through the outlet. The jet outlet may include a jet nozzle and a needle spindle adjustably mounted within the nozzle. The device preferably has an outer housing, the jet outlet being mounted with the outer housing towards its upstream end and the adjustable mounting arrangement serving to mount the diffuser member adjustably with the outer housing. The outer housing may be flared to an increased diameter towards its upstream end. The jet outlet is preferably mounted centrally of the outer housing by a support structure of open form that allows air to flow along the outer housing around the jet outlet. The support structure may include a gas^~ passage extending between the jet outlet and a gas port on the outside of the outer housing. The diffuser member may have a bore along its length that reduces continuously in internal diameter from its upstream end along a major part of its length. The bore may open at its downstream end into a section of increased diameter such that gas entering the section of increased diameter undergoes a pressure drop. Alternatively, the diffuser member may have a passage with a short upstream section that tapers to a smaller diameter in a downstream direction and opens into a longer downstream section that tapers in the opposite sense.

Respiratory therapy devices including an entrainment device, according to the present invention, will now be described, by way of example, with reference to the following drawings in which: '

Figure 1 is an external side elevation view of a first form of therapy device;

Figure 2 is a sectional side elevation view of the entrainment device within the therapy device of Figure 1;

Figure 3 is a sectional side elevation view showing the entrainment device of

Figure 1 and 2 coupled with a face mask and used in a CPAP mode; Figure 4 is a sectional side elevation view showing an entrainment device

coupled with a fapemask arranged in a bi-level PAP mode; and

Figure 5 is a sectional side elevation view of an alternative adjustable

entrainment device.

With reference first to Figures 1 ,and 2, the therapy entrainment device 1 is arranged to deliver a continuous mixture of air and oxygen at an elevated pressure (CPAP) to a patient. The device 1 has an outer housing 10 of cylindrical shape along most of its length and that flares outwardly along a region 14 to form an air inlet 11 at its upstream, left-hand end 12. The air inlet 11 is open to atmosphere. The opposite, right-hand or downstream end 3 of the device 1 provides a patient inlef and is shaped to be coupled with a patient interface, such as a mask or a removable mouthpiece 4 shown in Figure 1.

A support structure 13 inside the flared region 14 of the outer housing 10 supports a gas jet nozzle 15 in a fixed position centrally within the outer housing and just inside its open end 12. The support structure 13 is of an open form and may include several struts or structures of any other form that supports the gas jet nozzle 15 while also allowing air to flow through the support structure from left to right within the outer housing 10. The gas jet nozzle 15 includes a tubular outer housing 17 that is internally screw-threaded at its upstream, left-hand end and that tapers fo a narrower diameter at its downstream, right-hand end 18 to form an outlet orifice 19. The gas jet nozzle 15 contains a needle spindle 20 within it that is screw-threaded on its outer surface^" towards its left-hand end 21 and that is screwed into the thread in the outer housing 17. A slot 22 in the left-hand end face of the spindle 20 is shaped to receive the tip of a screw driver or similar tool (not shown) so that the spindle can be moved to different positions along the length of the nozzle housing 17 by screwing it in or out. A small bore passage 23 extends along the support structure 13, through the wall of the housing 10 where it is terminated by a short gas port 24. One end of oxygen tubing 25 is fitted over the gas port 24 and its other end extends to a source of oxygen at elevated pressure (above atmospheric pressure) such as a cylinder 26 of compressed oxygen via a regulator 27. In this way, a low flow of pressurised oxygen can be supplied to the gas jet nozzle 15 so that it emerges from the orifice 19 in a jet stream axially of the device 1 directed downstream towards the right-hand, patient end of the device. The rate of flow from the orifice 1 can be controlled by screwing the needle spindle 20 into the nozzle housing 17 (to reduce flow) or screwing it out (to increase flow).

The device 1 also includes a diffuser member 30 in the form of an internal sleeve supported in the housing 10 and projecting out of the housing at its downstream, patient end to provide the patient end 3 of the device. At its upstream end the diffuser member 30 has an entrance 32 that is aligned with the gas nozzle 15. The diffuser sleeve 30 is formed with a screw-threaded region 33 on its outside that engages a cooperating screw-threaded region 34 on the inside surface of the outer housing 10 so as to provide an adjustable mounting arrangement. The diffuser 30 also includes a manual adjustment member in the form of a handle, knurled ring 35 or the like projecting radially outwardly towards its patient end. By rotating the member 35 the diffuser 30 can be rotated and screwed into or out of the outer housing 10.

Internally, the diffuser 30 is divided into an upstream section 36 and a downstream section 37 towards the patient end of the device. The upstream section 36 occupies about two thirds of the length of the diffuser 30 and is provided by a bore 38 of circular section with a width or diameter that varies along the length of the section, being wider at its left-hand, upstream end than at its downstream end. More particularly, the bore 38 is of frusto-conical shape, tapering along its length and preferably has a surface that promotes turbulence of gas flowing along the bore. In this respect, the surface of the bore 38 may be roughened or formed with several concentric rings, steps or striations (or a combination of these) to encourage mixing of gas flowing over if. The upstream section 36 opens into the

downstream section through an opening 39, the diameter of the downstream section being about three times the diameter of the opening and substantially constant along its length. It will be appreciated that the gas mixture flowing along the upstream section 36 will undergo a pressure drop as it emerges from the ppening 39 because of the larger cross-sectional area of the downstream section 37.

When the handle or ring 35 is rotated to move the diffuser 30 to the left or right relative to the housing 10 it moves the entrance 32 of the diffuser closer to, or further from, the gas jet nozzle 15, which is fixed with the outer housing. Because the left-hand, upstream end 36 of the diffuser 30 is tapered internally the effective diameter of the diffuser, that is, the diameter at the region where the gas jet impinges on the diffuser, will change as the diffuser is moved along its length. Moving the diffuser 30 to the right, away from the gas jet nozzle 15 increases its effective size and^' results in more air being entrained along the device. This also has the effect of reducing the percentage of oxygen in the gas mix. In the arrangement described, however, it is possible to compensate for this, to maintain the same oxygen concentration, by moving the needle spindle 20 rearwardly (to the left) in the gas nozzle 15 so as to allow more oxygen through the gas jet orifice 19. In some devices movement of the diffuser could be mechanically linked to the gas jet spindle so that altering the effective size of the diffuser automatically adjusts the gas jet nozzle to maintain a constant oxygen concentration at different diffuser settings. Alternatively, the diffuser adjustment member 35 and the needle spindle 20 could be marked with calibrations so that it was readily apparent what changes in settings of these two controls were needed to achieve the desired flow rate of the gas mixture and its oxygen concentration.

The device 1 described above can be used directly with the mouthpiece 4 or it could be connected with some other form of patient breathing interface such as a face mask 30 shown in Figure 3. In this arrangement, ihe entrainment therapy device 1 is coupled to the only gas port 31 on the face mask 30 so that the patient has both to inhale and exhale through the therapy device 1. The patient is, therefore, exposed to elevated pressure during inhalation and exhalation phases, that is, a CPAP arrangement.

Alternatively, the entrainment therapy device 1 could be incorporated into a bi-level positive pressure arrangement as shown in Figure 4. In this arrangement the face mask 130 has two gas ports, namely a gas inlet port 131 to which the entrainment therapy device 1 is connected and an outlet port 132 incorpprating a combined one-way valve (arranged to enable gas to flow out of the mask but preventing flow into the mask through the port) and an adjustable patient relief valve 133. The patient relief valve 133 opens to allow gas flow out of the mask 130 when pressure in the mask rises above an adjustable threshold. This arrangement delivers bi-level positive pressure therapy to the patient. The arrangement is also shown as including a reservoir bag 134 between the entrainment device 1 and the inlet port 131. This can improve the effectiveness of the arrangement and can make use of the arrangement more comfortable for the patient.

Figure 5 shows an alternative enfrainment device in which the diffuser 30' differs from the diffuser 30 shown in Figures 2, 3 and 4 by having an internal surface of a different shape. In particular, the passage 38' through the diffuser 30' is divided into a relatively short left-hand, upstream section 36' with a relatively steep taper, wider at its upstream end, which opens into a longer downstream section 37' having a shallower taper of the opposite sense. The downstream section 37' continues with a constant internal diameter along a portion 39' towards the patient end. In this device 1 ' the oxygen jet from the nozzle 15' entrains air upstream of section 36', the gas mixture then flows to the patient via the downstream section 37' and the patient end portion 39'.

The present invention, when applied to a respiratory therapy device, can be used to enable the amount of air entering the device to be optimised and the percentage of oxygen in the mixture to be controlled. The term "gas" has been used herein to include vapours and gas or vapour mixtures.

Claims

An entrainment device (1, ) including a gas jet outlet (15, 15') aligned axially with an entrance (32) to a diffuser member (30, 30'), characterised in that the entrainment device has an adjustable mounting arrangement (33, 34, 35) by which the axial spacing between the gas jet outlet (15, 15') and the diffuser member (30, 30') can be adjusted, and that the diffuser member (30, 30') has an internal width that varies along a part at least of its length such that the effective size of the diffuser member can be varied by adjusting the axial spacing between the gas jet outlet (15, 15') and the diffuser member (30, 30').

A respiratory therapy entrainment device (1, ) including a patient inlet (3), an air inlet (11) open to receive atmospheric air, and a source (26) of pressurised oxygen, the entrainment device including an oxygen jet outlet (15) connected with the source (26) of pressurised oxygen, and a diffuser member (30, 30') having an inlet entrance (32) in communication with the air inlet (11), the oxygen jet outlet (15, 15') being aligned with the entrance (32) to, the diffuser member (30, 30') so as to entrain air within the diffuser member, characterised in that the therapy entrainment device has an adjustable mounting arrangement (33, 34, 35) by which the axial spacing between the oxygen jet outlet (15, 15') and the diffuser member (30, 30') can be adjusted, and that the diffuser member (30, 30 ) has an internal width that varies along a part at least of its length such that the effective size of the diffuser member can be varied by adjusting the axial spacing between the oxygen jet outlet (15, 15') and the diffuser member (30, 30') so as thereby \o alter the concentration of oxygen in the entrained gas mixture supplied to the patient inlet (3).

A device according to any one oi" the preceding claims, characterised in that the adjustable mounting arrangement includes a screw thread mechanism (33, 34) such that the axial spacing of the diffusor member (30, 30') from the jet outlet (15, 15') can be adjusted by rotating the diffusor member (30, 30') relative to its mounting.

4. A device according to any one of the preceding claims, characterised in that the surface of the interior (38) of the diffusor member (30, 30') is provided with a texture to increase turbulence.

5. A device according to Claim 4, characterised in that the texture is provided by one or more of the following: surface roughness, concentric rings, steps and striations.

6. A device according to any one of the preceding claims, characterised in that the jet outlet (15, 15') includes an arrangement (20) for adjusting gas flow through the outlet. _f

7. A device according to Claim 6, characterised in that the jet outlet (15) includes a jet nozzle (17, 18, 19) and a needle spindle (20) adjustably mounted within the nozzle (17).

8. A device according to any one of the preceding claims, characterised in that the

device has an outer housing (10), that the jet outlet (15, 15') is mounted with the outer housing (10) towards its upstream end, and that the adjustable mounting arrangement (33, 34, 35) serves to mount the diffuser member (30, 30') adjustably with the outer housing (10).

9. A device according to Claim 8, characterised in that the outer housing (10) is flared (14) to an increased diameter towards its upstream end (12).

10. A device according to Claim 8 or 9, characterised in that the jet outlet (15, 15') is mounted centrally of the outer hpusing (10) by a support structure (13) of open form that allows air to flow along the outer housing (10) around the jet outlet (15, 15').

11. A device according to Claim 10, characterised in that the support structure (13)

includes a gas passage (23) extending between the jet outlet (15, 15') and a gas port (24) on the outside of the outer housing (10).

12. A device according to any one of the preceding claims, characterised in that the diffuser member (30) has a bore j 38) along its length that reduces continuously in internal diameter from its upstream end along a major part of its length.

13. A device according to Claim 12, characterised in that the bore (38) opens at its downstream end into a section (37) of increased diameter such that gas entering the section (37) of increased diameter undergoes a pressure drop.

14. A device according to any one of Claims 1 to 11, characterised in that the diffuser member (30') has a passage (38') with a short upstream section (36') that tapers to a smaller diameter in a downstream direction and opens into a longer downstream section (37') that tapers in the opposite sense.