WO2021089977A1

WO2021089977A1 - Suction device

Info

Publication number: WO2021089977A1
Application number: PCT/GB2020/050978
Authority: WO
Inventors: Simon Hall
Original assignee: Airway Medical Ltd
Priority date: 2019-11-08
Filing date: 2020-04-20
Publication date: 2021-05-14
Also published as: GB201916244D0; GB2588800A; GB2588800B

Abstract

The present invention provides a suction device comprising: a collection container; an inlet in fluid communication with the collection container; a venturi pump having a motive fluid port, a suction port in fluid communication with the collection container, and a discharge outlet, and wherein the motive fluid port is adapted to receive a source of compressed propellant 'air' or propellant gas. The device conforms to all standards for High, Low, Thoracic and Pharyngeal Suction as set out in ISO 10079-3:2014.

Description

Suction Device

The present invention relates to a suction device particularly, but not exclusively, the invention relates to a medical suction device.

Suction devices may be used for medical or industrial applications, whereby it is necessary to remove a fluid or fluid-like substances such as powders or other debris to remove a blockage. In industrial application such fluids could be any unwanted substance, such as a spillage or escape of fluid. In medical applications a common need for suction is to clear a blocked airway which may occur, for example, as a result of vomiting, inhaling fluid or debris or bleeding in the nose or mouth. Accordingly, in emergency situations where CPR is required clearing the airway must be the first step.

Some existing medical devices are available for assisting clearing of an airway. For example, suction units or aspirators which are generally mains or battery powered. Such devices may be static or portable but even portable devices are generally large and weighty. For example a typical existing "portable" suction unit may be around 4 to 5kg and 15,000 to 20,000cm³ in size. Battery powered devices must be charged and therefore may be of limited use away from mains sources. Further such electric suction units may not be suitable for use in some environmental conditions, for example near water. The operation of electric suction units requires user training and may be complex. Electric suction units are also relatively expensive and require regular maintenance.

An alternate portable/compact solution is a manual suction pump. These may be used for emergency situations such as during CPR. Manual medical suction pumps generally have a simple hand operated pump connected to a collection canister and a catheter which can be inserted into the patients airway. While such devices may be of some assistance in CPR situations, they do not generally create a reliable or effective amount of suction. Thus, such manual devices may be unable to clear an airway and are not in common use in the medical field.

Accordingly there is a need for a suction device which in at least some embodiments overcome or obviates at least some of the disadvantages of existing devices. In accordance with an aspect of the invention there is provided a suction device comprising: a collection port configured to enable fluid to pass therethrough; an inlet in fluid communication with the collection port; a source of compressed carbon dioxide-free air or carbon dioxide-free propellant gas; a venturi pump having a motive fluid port, a suction port in fluid communication with the collection port, and a discharge outlet, wherein the motive fluid port is adapted to receive the source of compressed carbon dioxide-free air or carbon dioxide-free propellant gas, and wherein the discharge outlet is adapted to discharge exhaust compressed carbon dioxide-free air or carbon dioxide-free propellant gas therethrough; and in which the device further comprising either a collection container in communication with the collection port to receive fluid, or a non-return valve located at or adjacent the collection port to ensure fluid is expelled from the device to an external environment.

The device conforms to all standards as set out in ISO 10079-3:2014 for High, Low, Thoracic and Pharyngeal Venturi Suction.

Embodiments of the invention provide a suction device with a simple and robust method of operation. When compressed air or propellant gas from the source is discharged into the motive fluid port it passes through the venturi pump and out of the discharge port. As is known in venturi pumps, an orifice or nozzle provides a restriction within the body of the venturi pump and result in the fluid (in the present case the released compressed air or propellant gas) flow rate increases and the pressure decreases. The suction port is positioned at or proximal to the restriction such that the pressure drop causes a suction through the port. In embodiments of the invention this suction is in communication with the collection container such that a vacuum (which for the purpose of the invention will be understood to include a partial vacuum) is created and the inlet can be used to suck substances into the collection chamber. Advantageously, in its simplest form the suction device requires no additional moving parts and no additional source of power other than the compressed air or propellant gas.

The term "carbon dioxide-free" is used herein to refer to the source of compressed air or propellant gas comprising substantially no carbon dioxide. The source of compressed air or propellant gas preferably comprises no more than 5% carbon dioxide, preferably no more than 1% carbon dioxide, preferably no more than 0.5% carbon dioxide, preferably no more than 0.1% carbon dioxide.

Preferably, the device is a reusable suction device. As such, the device provides an environmentally friendly suction device which can be used multiple times, thereby reducing landfill waste. The device is preferably composed of autoclavable materials, preferably entirely composed of autoclavable materials, to ensure that the device may be reused. In one embodiment, the collection container is autoclavable.

In one embodiment, the collection container is an integral part of the suction device. In a further embodiment, the collection container may be releasably engage to the collection port to enable the collection container to be reused.

In one embodiment, the venturi pump further comprises a control valve configured to adjust one or more of: the suction force, the vacuum and/or the fluid flow through the device.

The propellant gas may comprise one or more, for example a combination of, high boiling point gases (i.e. gases which are liquid under pressure). Preferably, the propellant gas comprises gas(es) having a boiling point of at least -26.3 °C. In particular, the propellant gas may comprise one or more of: hydrofluoroalkanes (HFA) and/or hydrofluoroolefin (HFO), or any combination thereof. Suitable hydrofluoroalkanes include, but are not limited to, HFA 134a (boiling point: -26.3 °C), HFA 227 (boiling point: -16.4 °C) or a combination thereof. Suitable hydrofluroroolefin (for example liquid hydrofluoroolefin) include HFO-1234ze (boiling point: -19.5 °C) and R1234ZE (boiling point: 9.8 °C). In one embodiment, the propellant gas may comprise, or consist of, one or more inert gases. It has been found that suction devices which use low boiling point gases, such as for example carbon dioxide, CO2, (boiling point: -78.46 °C) are prone to rapid freezing.

Furthermore, conventional suction devices using low boiling point gases also comprise a number of metal components which increase the risk of freezing of the components. As such, there is a risk that these devices may malfunction and become inoperable during use.

The suction device may be a hand-held portable suction device. The suction device could be provided as a stand-alone emergency device.

In one embodiment, the collection container may comprise a reusable collection container, preferably composed of polysulphone or polycarbonate, or any combination thereof, configured to be in communication with the collection port. The reusable collection container is preferably configured to be releasably engageable with the collection port. For example, the reusable collection container and the collection port preferably each comprise one or more complimentary engagement features. Suitable releasably engagement features include, but are not limited to, cooperative male and female engagement features, push fit engagement and/or threaded engagement features.

In one embodiment, the reusable collection container comprises a collection container, preferably composed of polysulphone or polycarbonate, or any combination thereof, and a collection container liner (preferably composed of polythene) configured to be received in use within the collection container and to be in communication with the collection port. One or each of the collection container and the collection container liner may be releasably engageable to the collection port. For example, the collection port and one (or each) of the collection container and the collection container liner may comprise one or more complimentary engagement features. Suitable releasably engagement features include, but are not limited to, cooperative male and female engagement features, push fit engagement and/or threaded engagement features. In one embodiment, each of the collection container and the collection container liner are releasably engageable to the collection port. In one embodiment, the collection container is releasably engageable to the collection port, and the collection container is releasably engageable to the collection container liner. In one embodiment, the collection container liner is releasably engageable to the collection port, and the collection container liner is releasably engageable to the collection container. After use, the collection container can be disengaged from the collection port. The collection container liner can be removed from the collection container. The collection container and the collection container liner may be cleaned, for example autoclaved, ready for future use. In one embodiment, the collection container is autoclavable. In one embodiment, the collection container liner is composed of autoclavable material.

In one embodiment, the device comprises a collection container in communication with the collection port, in which the collection container comprises an inflatable container comprising an outer surface, an inner surface defining an internal cavity, and at least one air pocket extending therebetween. The at least one air pocket is preferably in communication with the discharge outlet to receive exhaust compressed air or propellant gas therefrom. The inflatable container is preferably moveable between a first collapsed non-operative configuration in which the at least one air pocket is collapsed, and a second operative configuration in which the at least one air pocket is inflated with exhaust compressed air or propellant gas to provide a rigid collection container. The inflatable container is preferably composed of polymeric material, such as for example polythene.

In some embodiments the fluid port may comprise a connector for connection to a compressed air or propellant gas line. As such the source of compressed air or propellant gas may comprise an external compressor. Such an arrangement may for example be useful in an industrial application where air lines are readily available. The connector may be any convenient form and may be selected to meet existing standards. In some embodiments the connector may be adapted to connect to an air gun (which are commonly used for in garages and the like).

In some applications, for example use as an emergency medical suction device, it may be desirable for the source of compressed air/propellant gas to be provided as a part of the suction device. Thus, the source of compressed air comprises a compressed air/propellant gas canister. The compressed air/propellant gas canister may be connected to the suction device or integrally formed with the suction device. The compressed air/propellant gas canister is in fluid communication with the motive fluid port to provide motive flow in use. In order to allow reuse of the suction device, the compressed air/propellant gas canister is removably connected to the suction device to allow the suction device to be reused. Such an arrangement may also enable the suction device to be used with a standardised compressed air/propellant gas canister. Changing/replacing of a canister would generally be very simple and rapid to perform - taking for example less than 5 seconds.

In one embodiment, the suction device is waterproof, and may be used in underwater environments. For example, the suction device may comprise waterproof seals located between one or more, preferably each, of the collection port, the inlet, the venturi pump, the (reusable) collection container and/or the non-return valve.

Additionally, there is potential for a disposable device, such as for example a single use, disposable device.

A cap may be provided for closing the collection container. The collection container may include an opening and the cap may close the opening. Conveniently the cap may provides the interface between the inlet, venturi pump and collection container. Such an arrangement may advantageously remove the need for any additional vents or openings in the container.

In some embodiments the cap may be reversibly connectable to the collection container. In other words the cap may be connectable to the container in a first orientation and also in a second orientation in which the cap has been generally inverted relative to the collection container. For example, the collection container may comprise a threaded connection for receiving the cap (for example a male thread) and the cap may comprises first and second screw threads (for example female threads) on opposing sides of the cap.

By providing a cap which is reversible the suction device may be assembled in either: a first configuration in which at least the inlet and the venturi pump are disposed within the collection container; or a second configuration in which the cap is reversed relative to the collection container such that said at least inlet and venturi pump are disposed of externally to the collection container. The first configuration may be a storage configuration. The second configuration may be an in use (or ready for use) configuration. This may allow the suction device to be supplied and/or stored in a compact configuration with the components of the suction device generally contained within the collection container. In the and/or a sterilisation seal when supplied in the first configuration. Thus, prior to use of the suction device the user may be required to remove or break a seal in order to remove the cap before re-orientating the cap in its reverse position. This ensures that the user knows the device is safe and ready for use.

Where the suction device includes a compressed air/propellant gas canister, the air canister may also be provided on or connected to the lid. The compressed air/propellant gas canister may also be positioned within the collection container in the first configuration and external to the container in the second configuration.

The inlet and venturi pump may be integral with the cap. A compressed air/propellant gas source, such as a canister, may also be integral with the cap.

The inlet may comprise flexible tubing. Accordingly, the suction from the inlet may be directed to a required location without the need to manoeuvre the entire suction devices.

Whilst the collection container could be a non-rigid container such as a bag to reduce the bulkiness of the device, the container may typically comprise a generally rigid container. For example, the container may be a polycarbonate container. The container may be a jar.

In some embodiments the collection container may be provided with an outlet valve, for example a non-return valve. The outlet valve, for example non-return valve, may be arranged to enable the collection container to maintain a suction and allow larger amounts of fluid to be drawn and secreted to the external atmosphere. Such an arrangement could be useful for example as an emergency medical device for battlefield medics. In one embodiment, the collection container comprises an outlet valve configured to open at a predetermined positive pressure, and an inlet valve for directing purge fluid under pressure into the chamber. The inlet valve may be a non-return valve. In one embodiment, the container may further comprise an internal diaphragm configured in use to open the inlet valve when a predetermined level of fluid is accumulated in the container.

The inlet valve may be connected to the source of compressed propellant gas.

The suction device may be a medical suction device, particularly a portable medical suction device. Accordingly, the inlet may comprise a catheter or Jankauer tip or a collection tube.

An embodiment of the invention will now be described by way of example only, with reference to the accompanying drawings in which:

Figure 1A is a schematic representation of the components of the suction device in accordance with an embodiment; Figure IB is a schematic representation of the components of the suction device in accordance with a further embodiment;

Figure 1C is a schematic representation of the components of the suction device in accordance with a further embodiment;

Figure ID is a schematic representation of the components of the suction device in accordance with a further embodiment;

Figure 2 is a schematic representation of the suction device of an embodiment in a first, pre-use, configuration;

Figure 3 is a schematic representation of the suction device of the embodiment of figure 2 in a second, ready-for-use, configuration; Figure 4 is an end view of the suction device of figure 2; and

Figure 5 is an example of a reversible cap arrangement for use in embodiments of the invention.

As seen in Figures 1 to 4, the suction device 10 of the invention comprises 5 main components: a collection container 1, an injection suction unit formed by a venturi pump 2, a closure cap 3 for the collection container, a source of compressed air/propellant gas in the form of a canister 4 and an inlet collection tube 5.

In Figure 1A, the collection container 1 is provided in the form of a polycarbonate container. In Figure IB, the collection container 1 further comprises a collection container liner 6a, in the form of a polythene collection container liner. The embodiment of Figure IB further comprises negative port 6b configured to equalize the negative pressure within the jar liner and thereby enabling the liner to be pulled towards the walls of the collection container 1.

In Figure 1C, the collection container 6 comprises an inflatable container comprising an outer surface, an inner surface defining an internal cavity, and a plurality of air pockets 6c extending therebetween. In the illustrated embodiments, the air pockets 6c are substantially elliptical in shape with wall portions 6d extending therebetween. It is however to be understood that the container may comprise any suitable number of air pockets of any suitable shape, and in any suitable location. Prior to use, the collection container 6 can be collapsed so as to have the smallest possible footprint. As such, the device of Figure 1C has minimum storage requirements and so can be effectively be stored in conditions where space is limited. The device 1 comprises a positive pressure port 6a in communication with the gas canister 4. During use, the positive pressure port 6a enables the air pockets 6c of the container to be filled directly from the gas canister 4 until inflated to provide a rigid container. The device 1 further comprises a pressure relief valve which is configured to close pressure port 6a once the air pockets 6c have been inflated.

Figure ID illustrates an embodiment in which the device has a non-return valve in communication with a container. The container 8 may be a rigid container or an air pocket container as described in more detail above. The container 1 may have any convenient shape and in the illustrated example is a cylinder. The container may for example have a capacity of between 0.25 and 10 Litres, dependent upon the desired application. The container may have any suitable capacity depending on the requirements for the device. For example, a typical medical emergency suction device may have a volume of around 0.5 litres (or for paediatric use this may be less, for example 0.25 litres). The container 1 includes a standard connection arrangement for receiving a closure, for example a threaded male collar for receiving a screw thread lid 3.

The injection suction unit 2 is a conventional static venturi pump arrangement. As best seen in the schematic representation of figure 1, the venturi pump comprises a motive fluid port 2a, to which the flow from the compressed air/propellant gas canister 4 is introduced. A suction port 2b is in fluid communication with the collection container. In the illustrated example the suction port is directly connected to an inlet la of the container 1 via a flexible tubing lb. It will, however, be appreciated that the suction port could be connected indirectly via the collection tubing 5 provided it is able to create a vacuum across the collection container 1 and cause a suction into the inlet collection tubing 5. The suction port 2b is positioned adjacent an orifice nozzle 2c formed within the body of the suction unit 2. The orifice causes a reduction in pressure and a resulting suction through the suction port 2b. The resulting combined flow is exhausted through the discharge outlet 2d. As shown in the embodiment of figures 2 to 4, the injection suction unit 2 may be integrally formed with the closure member 3 (for example by co- moulding the passageways and ports into the closure member). By way of example, in a typical embodiments suction unit could be formed by providing a venturi restriction of lmm in a tubing having a bore of around 8mm.

The closure member 3 is in the form of a threaded cap. The closure may be made from any convenient material such as injection moulded plastic or glass reinforced fabric. In the illustrated preferred embodiment it may be noted that the closure 3 is reversible relative to the container 1. As seen in figure 5, the cap has two female screw threads 3a, 3b which are arranged in a back to back arrangement with a closure plate 3c extending therebetween. This allows the cap 3 to be fitted in a first configuration relative to the container 1 and after removal to be inverted relative to the container and fitted in a second orientation. As will be explained in further detail below, in one configuration the cap 3 allows the components of the suction device 10 to be contained within the interior of the container 1 and in the reverse configuration of the cap 3 the components may be external to the container 1. One of the closure member 3 or the container 1 may include a rubber seal or the like to provide an airtight interface. The source of compressed air/propellant gas 4, is a compressed propellant gas canister. Such canisters are readily commercially available or a specifically configured canister could be used. The canisters generally have a button operated valve that allows the air/propellant gas to be released at a relatively high velocity. This airflow is directed into the motive fluid port 2a during use. Although the illustrated embodiment comprises a button operated valve, it is to be understood that the canisters may be operated by any suitable mechanism in order to release the air or compressed gas.

The inlet collection tube 5 is generally a flexible pipe which can be positioned as required to provide suction. The tube extends from a first end 5a which is connected to the closure 3 and open to the interior of the collection container 1 (in at least the in-use configuration) to an open tip 5b which may be freely directed by the user.

Use of the device will now be described. The suction device 10 is initially in a pre-use configuration as shown in Figure 2. The reversible cap 3 is in the inverted position such that the suction unit 2, air/propellant gas canister 4 and collection tubing 5 are all sealed within the container 1. This may for example be a sterile arrangement with a seal provided to protect the suction device (for example a shrink wrap package may be provided around the suction device). The user removes the cap 3 and then replaces the cap in the reverse orientation relative to the container 1. This places the collection tubing 5, air/propellant gas canister 4 and suction unit 2 on the exterior of the container. The collection tubing 5 may then be placed as required such as proximal to a blockage, for example in the case of a medical emergency device the collection tubing may be a catheter which can be placed in an obstructed airway.

The user then simply activates the compressed air source - for example pressing on a valve of the compressed air/propellant gas canister 4. This releases air/propellant gas through the suction unit 2, resulting in a vacuum (or partial vacuum) being created in the container 1. Thus, the device could apply a suction of for example 0 to -80KPa, or greater than -80 kPa, suction to be applied through the collection tubing 5.

As an example, for a simple application an embodiment of the invention may use a 200g canister 4 holding approximately 170g of gas. For medical applications, an output pressure of 4 to 6 Bar (400 to 600Kpa) is standard. A typical suction rate could be around 0.5L in 2 seconds, which equates to a 15Litre per minute flow rate. Approximately 4g of gas would be required per 0.5L, such that a standard sized gas canister may be able to displace around 21 litres of fluid. In the case of a device for use in CPR and the like, it may be noted that the typical maximum fluid capacity of adult lungs is between 4 to 10 litres of fluid. As such, in a situation such as drowning this could be the approximate maximum volume required. As such a custom device could have a reduced capacity compressed air/propellant gas canister of around 50g. This would be sufficient to provide 42 seconds of suction and to empty a 10 litre volume. Such a device could have a compact footprint of less than 950cm³ and a weight of 200g or less.

Bench tests have shown embodiments of the device to produce a minimum of -60KPA vacuum with 25+ LPM flow rate which has been found to be more than sufficient to satisfy ISO 10079-3:2014 for High, Low, Thoracic and Pharyngeal Suction. The device can be manually adjusted to provide 0 to -60Kpa and 0 to 25+ LPM; thus satisfying High, Low, Thoracic and Pharyngeal Suction parameters of ISO 10079-3:2014. Indeed, all such embodiments conform to all requirements of ISO 10079-3:2014.

With reference to the embodiment of Figure ID, the container in the illustrated embodiment comprises an internal diaphragm 8a. At a predetermined fluid level, the diaphragm 8a is in communication with switch 8b to operate valve 8c. This enables positive pressure to enter the container 8 via non return valve 8d. The positive pressure causes non-return valve 8e at the base of the container to open, and for non-return valve 8f to close, thus releasing the excess fluid. Such an embodiment enables fluid contained in the container 8 to be expelled, for example to allow re-use of the device. Whilst in some circumstances (such as sterile medical environments) this may be undesirable, in others it may be useful for example in emergency or battlefield medicine. As the fluid is released, the diaphragm 8a relaxes causing valves 8c, 8d and 8e to close. Valve 8f remains open under negative pressure thereby drawing fluid into container 8.

Although the embodiment described above may be particularly suitable for use as an emergency medical device it will be appreciated that the invention is not limited to such uses. For example, a suction device may be useful to engineers or mechanics to clear blockages in orifices or conduits. A suction device may be preferable to the use of blown air/propellant gas which may merely displace debris elsewhere into the engine and may avoid stripping down and reassembly which may be time consuming. In such situations it may be preferable to provide a device which is connectable to a compressed air/propellant gas line or air gun rather than requiring a canister of compressed air to be used with the suction device.

Likewise, it will be appreciated that embodiments of the invention may be useful in other practical applications such as DIY and trades. For example, to provide quick and simple collection of escaped liquid in plumbing applications.

An advantage of the suction device according to embodiments is the lack of moving parts or requirement for a source of electrical energy. Not only is this particularly useful for an emergency device which may be left in-situ and unused for an extended period it may also enable the device to be used in all environments. As such, embodiments may be used in sub-aqua applications. For example, when carrying out maintenance underwater a suction device in accordance with an embodiment of the invention could be used to remove debris.

It is however to be understood that the suction device, according to embodiments, of the present invention may comprise a power source, such as for example a battery source, configured to activate the device.

Whilst embodiments of the invention have been described above, the skilled person will appreciate that other modifications may be possible without departing from the scope of the invention. For example, where more powerful suction is required it may be possible to run a number of suction pumps in sequence from the exhaust of the previous device. The devices could be arranged either in parallel or series depending upon the requirements.

The skilled person will readily appreciate that embodiments of the invention could be readily tailored to a particular application for example an application requiring a particular level of suction. For example if the size of the venturi can be varied and/or a restriction/flow resistor could be provided in the vacuum line. In some embodiments it may be desirable for example to provide a variable suction level with a control element provided for adjusting the venturi or restriction. To gain greater suction, for example for an industrial type application, the invention could be scaled. For example the size of the tubing could be adjusted along with the size of the source of compressed air.

Claims

1. A suction device comprising: a collection port configured to enable fluid to pass therethrough; an inlet in fluid communication with the collection port; a source of compressed carbon dioxide-free air or carbon dioxide-free propellant gas; a venturi pump having a motive fluid port, a suction port in fluid communication with the collection port, and a discharge outlet, wherein the motive fluid port is adapted to receive the source of compressed carbon dioxide- free air or carbon dioxide-free propellant gas, and wherein the discharge outlet is adapted to discharge exhaust compressed carbon dioxide-free air or carbon dioxide-free propellant gas therethrough; and in which the device further comprising either a collection container in communication with the collection port to receive fluid, or a non-return valve located at or adjacent the collection port to ensure fluid is expelled from the device to an external environment.

2. A suction device as claimed in claim 1, in which the device is a reusable suction device.

3. A suction device as claimed in claim 2, in which the device is composed of autoclavable materials.

4. A suction device as claimed in any one of claims 1 to 3, in which the device comprises an integral collection container.

5. A suction device as claimed in any one of claims 1 to 3, in which the device comprises a collection container releasably engaged to the collection port.

6. A suction device as claimed in any preceding claim, in which the venturi pump further comprises a control valve configured to adjust one or more of: the suction force, the vacuum and/or the fluid flow through the device.

7. A suction device as claimed in any preceding claim in which the source of compressed carbon dioxide-free gas or carbon dioxide-free air comprises one or more of: hydrofluoroalkanes (HFA) and/or hydrofluoroolefin (HFO), propellant gas or any combination thereof.

8. A suction device as claimed in claim 7, in which the one or more hydrofluoroalkanes are selected from HFA 134a, HFA 227, or a combination thereof.

9. A suction device as claimed in either of claims 7 and 8, in which the one or more hydrofluroroolefin is HFO-1234ze or R1234ZE.

10. A suction device as claimed in any preceding claim, further comprising a propellant gas.

11. A suction device as claimed in any preceding claim, in which the device comprises a collection container, and the collection container comprises a collection container and a collection container liner configured to be received in use within the collection container and to be in communication with the collection port.

12. A suction device as claimed in any preceding claim, in which the device comprises a collection container in communication with the collection port, in which the collection container comprises an inflatable container comprising an outer surface, an inner surface defining an internal cavity, and at least one air pocket extending therebetween.

13. A suction device as claimed in claim 12, in which the at least one air pocket is in communication with the discharge outlet to receive exhaust compressed air or propellant gas therefrom.

14. A suction device as claimed in any preceding claim, in which the device is waterproof.

15. A medical suction device comprising a suction device as claimed in any preceding claim, wherein the inlet comprises a catheter.

16. A suction device as claimed in any preceding claim, further comprising a cap for closing the collection container, and wherein the cap provides the interface between the inlet, venturi pump and the collection container.

17. A suction device as claimed in claim 16, wherein the cap is reversibly connectable to the collection container such that the suction device may be assembled in: a first, storage, configuration in which at least the inlet and the venturi pump, and optionally the compressed air or propellant gas canister, are disposed within the collection container; and a second, ready, configuration in which the cap is reversed relative to the collection container such that at least the inlet and the venturi pump, and optionally the compressed air or propellant gas canister, are disposed externally to the collection container.

18. A suction device as claimed in claim 17, in which the collection container comprises a threaded connection for receiving the cap and the cap comprises first and second screw threads on opposing sides of the cap.

19. A suction device as claimed in claim 16 or 17, wherein the collection container comprises a seal to ensure an air tight seal with the suction device and to ensure vacuum is maintained.

20. A suction device as claimed in any one of claims 17 to 19, wherein the inlet and venturi pump are integrally formed with the cap.

21. A suction device as claimed in any preceding claim, wherein the collection container further comprises an outlet valve which opens at a predetermined positive pressure and an inlet valve for directing purge fluid under pressure into the chamber.

22. A suction device as claimed in claim 21, wherein the inlet valve is a non-return valve.

23. A suction device as claimed in claim 21 or 22 wherein the container further comprises an internal diaphragm which opens the inlet valve when a predetermined level of fluid is accumulated in the container.

24. A suction device as claimed in any of claims 21 to 23, wherein the inlet valve is connected to the source of compressed propellant gas.