Gas Trap Device For An Intravenous Injection

Abstract

A gas trap device for an intravenous injection comprises longitudinal extending passageways, an inverted, U-shaped passageway provided between and communicated with the longitudinal extending passageways, and a trap chamber provided at the top portion of the inverted, U-shaped passageway so as to prevent a gaseous material contained in a transfusion liquid from entering the body.

Description

The present invention relates to a gas trap device for removing bubble or gas from a transfusion liquid during intravenous injection.

In the prior art, gas trap devices for use in blood transfusion etc. are provided at the wall portion in the neighbourhood of a projector or needle, for example, in a manner to form a bulging space, to permit bubble or gas to be removed from a transfusion liquid. The transfusion liquid flowed through a straight passageway is passed at the bulging space where bubble or gas rises and degassing is effected. In the degassing devices as above-mentioned there are encountered drawbacks that the rising of bubble or gas is prevented by the axial flow of a transfusion liquid and the removal of gas or bubble from a transfusion liquid is not necessarily complete.

When an additional liquid medicine, e.g. cardiac etc. is added to a transfusion liquid in the conventional gas trap device, a rubber tube is connected at the forward end of the degassing device and an injection needle is pierced through the rubber tube into the transfusion liquid. A liquid medicine thus added to the transfusion liquid in the neighbourhood of the degassing device is transfused to the human body without being intimately mixed with the transfusion liquid.

It is a primary object of the present invention to provide a gas trap device which is capable of more complete removal of bubble or gas and foreign material from a transfusion liquid as well as capable of an intimate mixing of an additional medicine liquid with a transfusion liquid.

The gas trap device according to the present invention comprises longitudinal extending passageways, an inverted, U-shaped passageway provided between and communicated with the longitudinal extending passageways and a covering means for keeping air-tight the liquid passageway, the top portion of the inverted, U-shaped passageway being made larger in cross-sectional area than the other passageways so as to remove the bubble or gas from a transfusion liquid.

The present invention can be more fully understood from the following detailed description when taken in connection with reference to the accompanying drawings, in which:

FIG. 1 shows a blood transfusion set in which a gas trap device according to the present invention is used;

FIG. 2 is a view in cross section showing the gas trap device and its connection;

FIG. 3 is a cross sectional view taken along line II--II of FIG. 2;

FIG. 4 is a cross sectional view of the gas trap device;

FIG. 5 is a plan view of the gas trap device;

FIG. 6 is a plan view showing a filter mesh of FIGS. 2 and 3;

FIG. 7 is a cross section of a rubber plug as used in FIGS. 2 and 3;

FIG. 8 shows a holding cylinder used in the gas trap device of FIGS. 2 and 3;

FIG. 9 shows a bottom view of the holding cylinder;

FIG. 10 is another embodiment of the gas trap device showing the major parts thereof; and

FIG. 11 is a further modification of the gas trap device according to the present invention.

Let us now explain the embodiments of a gas trap device according to the present invention by reference to the drawings. FIG. 1 shows a diagrammatic view of a blood transfusion set. Reference numeral 1 shows a main vessel arranged at a higher place. The main vessel may be a blood transfusion bottle or bag. The main vessel 1 is connected through a penetrating needle 2 to the blood transfusion set which is connected through a drip chamber 4 and gas trap device 7 to an injection needle 5. Between the drip chamber 4 and the injection needle provided with the gas trap device there is provided a clamp 6. The adjustment of the clamp 6 permits a proper amount of liquid to be injected through the injection needle 5 into the human body.

To explain the gas trap device in more detail the gas trap device 7 is shown in FIG. 2 to be connected at each end. The gas trap device per se is made of a synthetic resin and has longitudinal extending passageways 8a, 8b and an inverted, U-shaped passageway 9 disposed at a middle between the passageways 8a and 8b. The inverted, U-shaped passageway 9 is constructed as such that, as shown by arrows in FIG. 2, a liquid introduced from the passageway 8a is, upon contact with an abutting wall 10, passed upwards through a bore 11a to a trap chamber provided at the top portion of the inverted, U-shaped passageway and, after diffusion, is flowed downwards through another bore 11b to the passageway 8b. The bottom portion of the gas trap device 7 confronting the trap chamber 12 is flattened so as to effect an easy attachment to the human body. The trap chamber constitutes a cylindrical space surrounded by a holding cylinder and has an extremely larger capacity than the amount of liquid passed beyond the inverted, U-shaped passageway 9. When the liquid is passed through the trap chamber 12 bubble or gas present therein is trapped within the trap chamber.

As shown in FIGS. 8 and 9 a holding cylinder 13 has a pair of cup-shaped bores 11a, 11b at the bottom portion thereof and fitted within the cylindrical wall of the gas trap device 7 per se. The holding cylinder 13 has an annular shoulder 15 at the bottom portion of the cylindrical wall 14 and is so designed as to securely hold a filter mesh on the top surface of the abutting wall which is in the same plane as the annular shoulder. As a filter mesh use is made, for example, of a disk-like filter mesh (37 .mu. pore size) of 9 mm in diameter. Within the inner wall of the cylindrical wall 14 there is provided a projection which is fitted into a groove 18 provided in an outer wall of the holding cylinder 13. This prevents any displacement of the holding cylinder 13 with respect to the cylindrical wall. As will be understood from the drawings the bores 11a, 11b are arranged at each side of the abutting wall 10.

As shown in FIGS. 2 and 3 a member such as rubber plug 19, through which additional liquid is introduced, may be sealed, as required, over the upper opening of the trap chamber 12. Before assembly the member 19 is in a position shown in FIG. 7 and has a plate-like portion 20 around which a cylindrical mating side wall 21 extends downwards. When the member 19 is assembled, the plate-like portion 20 is fitted over the opening of the cylindrical wall 14 to permit the mating side wall to be resiliently snap-fitted in a liquid-tight fashion over the cylindrical wall due to the resilience of the rubber plug 19. In this case a projection provided on the inner end portion of the mating side wall is snap-fitted over an annular projection 23 of the cylindrical wall portion 14 to permit the under-surface of the plate-like portion 20 to be urged downwardly relative to the top end of the holding cylinder 13, thereby securing the holding cylinder in place. At the liquid entering end of the gas trap device 7 there is connected one end of a tube 24 the other end of which is connected to the drip chamber 4. Over the outer periphery at the liquid discharging end of the degassing tube 7 a tapered cannula 5a is fitted having a needle 5.

When the gas trap device of the above-mentioned structure is used, transfusion blood can be supplied from the tube 24 with the trap chamber 12 kept underside and any air trapped within the trap space rises in the liquid passageway 8 and is degassed out of the needle 5. In this case, the trap chamber is filled with the liquid. Then a transfusion operation is effected with the trap chamber kept underside. When the fluid rises along the inverted, U-shaped passageway 9 bubbles of gas present in the liquid rise within the trap chamber 12 to permit the rising of the bubbles of gas to be promoted with the result that it is easily trapped within the trap chamber. This assures a degassing operation. Filter meshes 16 are provided one at the entry side and one at the discharge side of the inverted, U-shaped liquid passageway. Therefore, a transfusion liquid must be passed through filter mesh 16 and bore 11a into the trap chamber and be passed through filter mesh 16 and bore 11b out of the trap chamber. Since the liquid is passed through the filter mesh twice, any foreign matter is removed as well as a degassing operation is promoted due to the presence of a filter mesh at the discharge side of the inverted, U-shaped passageway. The filter mesh is usually required in the blood transfusion. However, it is not required in the transfusion of preliminarily refined liquid medicine etc.

When an additional liquid medicine is to be added to the transfusion fluid, a transfusion needle is pierced through the portion 20 of the rubber plug into the trap chamber 12. Since the needle is pierced into the eddy transfusion liquid caused by the inverted, U-shaped passageway 9 a liquid mixing operation is further promoted, which is partly aided by the presence of the filtering mesh. Thus, a sufficient stirring or agitation is assured. When a liquid medicine is added through a rubber tube connected at the drip chamber side of the gas trap device a mixing operation is effected at the inverted, U-shaped passageway and trap chamber 12 and filter mesh 16.

FIG. 10 shows another plug member through which another liquid is added by means of a needle to a transfusion liquid. Into the opening of a cylindrical wall 25 there is fitted a plug member 26 over which a thermally shrinkable tube 27 may be fitted. It is also possible to form an outer threaded portion at the periphery wall of the cylindrical wall 25 which is in mesh with an inner threaded portion provided at the inner periphery of the plug member. It will be clear that the other anchoring means may be used in this case.

When another liquid is added through a rubber tube connected at the drip chamber side of the degassing tube it is not particularly necessary to provide any plug member at the trap chamber 12. In this case the opening of the cylindrical wall 28 may be covered with a synthetic resin dish plate 29 which is either thermally fused or adhesively bonded to the top end of the cylindrical wall 28. A filter mesh 30 may be adhesively bonded to the shoulder portion 15 and abutting wall 10.

In the above embodiments, use is made as a filter mesh of such material as nylon mesh. However, as a filter mesh, there may be used a variety of porous materials such as, for example, polyvinyl chloride, polyethylene, polypropylene, polycarbonate, those sintered or compression formed materials made of the other powdered synthetic resins, as well as inorganic porous materials such as, for example, fiscuit diatomaceous earth, glass fiber, asbestos, metal sintered body etc. These porous filter materials have a porous diameter of 20-150 .mu.. Preferable is a filter material capable of eliminating particles whose size ranges between 3 and 80 .mu.. These porous materials, unlike those flattened meshes, are capable of catching any foreign matter not only at the surface but also at the inside thereof. Since the foreign matter is caught in a dispersed manner, lesser clogging of the mesh is encountered as compared with the amount of the foreign matter as caught. Even if the amount of the foreign matter so caught is increased, the flow resistance of the liquid is not so increased, thereby assuring a long service of life. The foreign matter once caught does not tend to pass through the filter mesh.

As will be understood from the above explanation the present invention provides a gas trap device for liquid transfusion capable of assuredly removing bubble or gas from a transfusion liquid as well as adding another liquid to the transfusion liquid. This assures an easy transfusion operation as well as easy addition of another liquid to the transfusion liquid without involving any dangerous result.

Claims

What we claim is:

1. A gas trap device for an intravenous injection comprising longitudinally extending passageways, an inverted U-shaped liquid passageway provided between and communicated with said longitudinally extending passageways, and covering means provided over the inverted U-shaped liquid passageway for keeping air-tight the liquid passageway, the top portion of said inverted U-shaped liquid passageway being larger in cross-sectional area than the other passageways, thereby providing a gas trap chamber.

2. The gas trap device as claimed in claim 1 wherein said covering means is a rubber plug through which additional liquid can be introduced.

3. The gas trap device as claimed in claim 1 in which said covering means is a plastic plate.

4. The gas trap device as claimed in claim 1 in which a filter mesh is provided in said U-shaped liquid passageway.

5. The gas trap device as claimed in claim 1 in which a filter mesh is provided at the inlet to said U-shaped liquid passageway and another filter mesh is provided at the outlet of said U-shaped liquid passageway.

6. The gas trap device as claimed in claim 4 wherein said filter mesh is a plastic mesh.

7. The gas trap device as claimed in claim 4 wherein said filter mesh is a disc of porous material.

8. The gas trap device claimed in claim 4 wherein said gas trap chamber is surrounded by a holding cylinder which serves to hold said filter mesh in position relative to said U-shaped liquid passageway.

9. The gas trap device claimed in claim 4 wherein said filter mesh is thermally fused to the bottom portion of said gas trap chamber.

10. The gas trap device claimed in claim 4 wherein said filter mesh is adhesively bonded to the bottom portion of said gas trap chamber.