GB2224957A - Water trap - Google Patents

Abstract

A water trap, in the air line of a respirator for administration of anaesthetics or a mechanical breathing system, comprises a membrane 8 that allows passage of water into container 9 but prevents substantial passage of gas. The membrane may be formed of an absorbent material which forms a barrier to gas when saturated with water, for example, a polytetrafluorethylene based hydrophilic material. Alternatively the membrane may be formed of a material that will allow diffusion of water therethrough for example, a hydrogel supported on plastics netting. Container 9 has a valve or is removable for emptying. <IMAGE>

Description

WAT##R TRAPS This application relates to water traps and more particularly to water traps for use in pressurised gas systems in which it is desirable to have the facility of removing the water trap while causing minimum disruption to the gas system.

For medical applications, for example respirators for administration of anaesthetics or ventilators or other mechanical breathing systems, which might be used with a humidifiers relatively large amounts of water vapour which may be contanusnated bacterially or virally, condenses in the tubes of the apparatus and has to be collected in water traps. These water traps must be periodically emptied and while so doing it is desirable that the pressure in the lines is not affected.In order to achieve this various valve devices have been used used in association with hitherto known removable water traps to close the line leading from the gas system to the water trap when the trap is reiwved# When the trap is replaced, however, and the valve reopened the pressure in the water trap must equalise with the pressure in the adjacent part of the system and this causes at least a temporary reduction in the overall pressure in that part of the system.

.Moreover, because there is a direct flow passage between the gas line and the container any contamirlants in the gas line originating from the patient can pass with the water into the trap so that the person emptying the trap may be at risk.

Further, external contaminants can be introduced into the gas system from the air in the trap when it is reconnected to the system.

According to another proposal the trap is ernptied through a suction line. While this reduces the risk of cross-contamination it increases the problem of pressure fluctuation in the gas system.

This invention provides a water trap system for use in a gas pressure system which avoids these problems.

According to the invention a filter/diffusion membrane is placed between the gas line and the container of a water trap, the m,embrane being formed of a material that at least when wet allow passage of water but prevents substantial passage of gas.

The membrane material used according to the invention may be, for example, an absorbent material that when at least partially saturated with water forms a barrier to passage of gas and when fully saturated allows further water to pass. Alternatively the membrane may be a material that will allow diffusion of water therethrough but not allowing diffusion of air.

Numerous absorbent film materials that are satisfactory for use in the invention are commercially available. One preferred material is a polytetrafluorethylene based hydrophyllic membrane material. Other membranes that can be used, for example, are acrylic copolymer membranes, optionally supported on nylon or polyester net, or polysulphone or polyamide v branes.

As diffusion type materials there may be mentioned various materials that are commonly used as water--based dressing materials and which comprise hydrogels supported, for example, on plastics netting or the like. Examples of such materials are sold under the trade names "Vigilon" and Ilcelipermil. "Vigilon" comprises a 96% water hydrogel supported on a polyethylene net.

The membrane material may need to be supported in a frame or other support if its wet-strength is insufficient to allow it to be self-supporting.

The invention will now be described in greater detail by way of example with reference to the drawings in which Fig. 1 is a schematic view of a complete ventilator circuit; and Fig. 2 is a schematic view of one form of water trap.

As shown in Fig. 1 a ventilator circuit includes a ventilator (1) having input and output lines (2) and (3) respectively.

Line (2) which leads to to the patient includes a humidifier (4) and a water trap (5) positioned at a low point in the line. The return line (3) also includes a water trap (6) at a low point in the line.

As shown in Fig. 2, according to the invention one form of water trap comprises a head portion (7) detachably connected into the gas line (2) or (3) by connector means (not shown). The head portion (7) comprises a chamber closed at its lower side (8) by a wall formed wholly or partially of a filter diffusion membrane of polytetraflurethylene based hydrophillic material. The water trap (5) or (6) also includes a jar or other container (9) which is disconnectably connected to the head portion (7) at (10).

Such disconnectable connection may, for example, comprise a push fitting or a screw thread or bayonet fitting.

Alternatively the container may be permanently fixed to the head portion and provided with a drain means for example a drain tap or plug or means for connection to a source of suction.

With the water trap of the invention the container (9) can be emptied without any substantial change of pressure in the gas lines 2 and 3 because the membrane forms a gas tight seal in the line. A further very considerable advantage is that because the gas lines are never open to unsterile ambient air the risk of cross-infection of a patient is reduced and any viral or bacterial contamination originating from the patient and present in the gas lines is maintained within the circuit thus avoiding contamination of the ambient. The filtering properties of the membrane may also prevent such viral or bacterial matter from passing into the collector so that there is a reduced risk to the person emptying the collector. If the membrane material itself will not resist passage of bacterial or viral oontaminants antagonists to such containnants can be incoporated in the material of the membrane.

Claims (9)

CLW

1. A water trap system for use in a gas pressure system and comprising a portion for attachment in a gas line and a container for collected water, wherein there is placed between the gas line and the container a filter/diffusion membrane formed of a material that at least when wet allows passage of water but prevents substantial passage of gas.

2. A system according to claim 1 wherein the membrane material is an absorbent material that when at least partially saturated with water forms a barrier to passage of gas and when fully saturated allows water to pass.

3. A system according to claim 2 wherein the absorbent material is a polytetrafluorethylene based hydrophillic membrane material

4. A system according to claim 1 wherein the membrane material is a material that will allow diffusion of water therethrough but will not allow diffusion of air.

5. A system according to claim 4 wherein the diffusion material is a supported hydrogel.

6. A system according to claim 5 wherein the hydrogel is supported on plastics netting.

7. A system according to any one of claims 1 to 6 incorporated in a gas pressure system for medical applications.

8. A system according to claim 7 wherein the gas pressure system is a respirator for administration of anaesthetics or a mechanical breathing system.

9. A gas pressure system incorporating at least one water trap system according to any one of claims 1 to 5.