Apparatus For Drawing Liquid Such As Blood

Abstract

In an apparatus for drawing liquid, especially for drawing blood, there is provided a stationary piston and a longitudinally extending container, open at one end, which receives the piston and is axially displaceable in relation to the piston to form a pump together therewith. A communication is provided through the piston from an inlet pipe to the space in the container closed off by the piston.

Description

The present invention relates to an apparatus for drawing blood or other liquid from a patient or a vessel, receptacle or the like. More particularly the invention relates to an apparatus for drawing blood in those instances where a number of blood samples are to be drawn from one patient.

When drawing a number of blood samples it is now usual to dispose one piercing end of a cannula within the vein of the patient, the opposite end of the cannula being adapted to be inserted through a resilient stopper provided on a vacuum container. A plurality of vacuum containers are connected and disconnected in succession to the cannula, valve means being provided to keep the flow passage through the cannula closed when no vacuum container is connected to the cannula.

Vacuum containers are preferred when multiple samples of blood are drawn from one patient due to the fact that these containers may be delivered from the manufacturer in a completely closed condition the interior of the container being sterilized for example by gamma ray radiation. However, the process of exhausting the containers and closing them at an underpressure raises the manufacturing cost of the container to a substantial degree. There is therefore a need for an apparatus which may replace the vacuum container and in which the underpressure necessary for drawing the blood from the patient through the cannula is created when the container is connected to the cannula.

An object of the present invention is to provide a new and novel apparatus for drawing blood or other liquid in which the container receiving the liquid is delivered as an open container and the necessary underpressure will be created therein at the moment when the container is used to receive the liquid.

According to the invention there is provided an apparatus for drawing liquid comprising a piston having a piston rod, support means supporting the piston at the piston rod, an inlet pipe supported by the supporting means, a longitudinally extending container, open at one end, of substantially uniform cross sectional area over at least a substantial part of its length from the open end, displaceably receiving the piston, means on the piston sealingly engaging the inner surface of the wall of the container, means forming a passage open at the inlet pipe and at the end face of the piston opposite to the piston rod to provide communication between the inlet pipe and said face of the piston, the container being axially movable on the piston to form together therewith a cylinder piston type pump.

An illustrative embodiment of the invention will now be described in detail with reference to the accompanying drawing in which

FIG. 1 is an exploded perspective view of an apparatus according to the invention in an advanced embodiment thereof; and

FIG. 2 is a fragmentary sectional view of the apparatus.

Referring now to the drawing a support means indicated generally by reference numeral 10 is formed as a cylinder case comprising two halves 11 and 12, respectively, of a plastic material, which are hinged by a web of said material at 13 and are to be interconnected at edge surfaces 14 when the two halves are closed together to form the complete cylinder case. The two halves form each one half portion 15 and 16, respectively, of an end wall. The apparatus further comprises a cylindrical inner sleeve 17 also of a plastic material having an end wall 18, which is dimensioned to be disposed inside the cylinder casing 10 inwardly of a projecting inner rim 19 thereon. A piston 20 formed integrally with a piston rod 21 as a unit of a plastic material which may be provided as a plunger, forms a pin 22 having a flat cylindrical head 23 and is adapted to be disposed inside sleeve 17 the headed pin being inserted through an opening 24 formed by end wall 18 of sleeve 17. The unit thus formed by sleeve 17 and piston 20 is disposed in the open cylinder casing 10 the headed pin 22 being received in an undercut cylindrical blind hole 25 in the two end wall portions 15 and 16 when halves 11 and 12 are subsequently closed to form the cylinder casing. Piston rod 21 has to be non-rotatably connected with the cylinder casing which may be achieved by using a glue in hole 25 or by giving the pin and/or the head and the hole a non-circular form. However, sleeve 17 has to be rotatably mounted on the pin between the outer cylinder casing 10 and piston rod 21. On the piston rod there is rotatably mounted in an annular groove therein at the end opposite to the piston 20 a washer 26 of a resilient material such as rubber or a rubber like plastic material. This washer has at the periphery thereof a notch 27 which is arranged to engage an inner projection 28 of sleeve 17 at the end wall 18 thereof and thus it will be seen that the washer will be rotated together with the sleeve.

On the outer side of the end wall portion 16 of the cylinder casing 10 there is provided a projecting hollow stud 29 of truncated form, over which a cannula 30 forming an inlet tube may be fitted, communication thereby being provided between the passage through the cannula and the passage through the stud 29. In a first angular position of sleeve 17 a through opening 31 in the end wall 18 thereof is opposite stud 29 to be in communication therewith. An axial passage 32 extends through piston rod 21 and piston 20 and opens in the end face of the piston rod opposite to stud 29 and in the end face of the piston and in said first angular position an opening in washer 26 registers with this passage. In a second angular position of sleeve 17 a through opening 33 in the end wall of the sleeve communicates with a through opening 34 in the end wall portion 15 of the cylinder casing and a further axial passage 35 extending through piston rod 21 an piston 20 opens in the end face of the piston rod opposite opening 34 and in the end face of the piston an opening 36 in washer 26 being in register with the passage in said second position. The latter passage and the associated openings in the cylinder casing, the sleeve and the washer are of a larger diameter than passage 32 and the associated openings. Thus it will be seen that in the first angular position of the sleeve and the corresponding position of the washer there is communication from the pointed end of cannula 30 to the end face of the piston the communication from opening 34 in the cylinder casing to the end face of the piston being closed at the end wall of the sleeve and at the washer, and in the second angular position of the sleeve there is communication from opening 34 to the end face of the piston the communication from the pointed end of the cannula to the end face of the piston being closed at the sleeve and at the washer.

A container 37 of the test glass type consisting of a cylindrical tube of plastic, glass or other suitable material, open at one end and closed at the other is provided at the open end with a ring 38 forming an outer rim of the container. This ring has a projection 39 preferably of the saw tooth form. The container may be moved axially over the piston which is provided with a circumferential sealing gasket 40 of the O-ring type to sealingly engage the inner surface of the container wall. In the sleeve wall there is provided an axial slot 41 receiving projection 39 when the container is moved axially over the piston, and projection 39 is of a sufficient radial length to extend through the slot into a groove system provided in the inner surface of cylinder casing 10. This groove system includes an axially extending groove having a wider part 42 and a narrower part 43, a further axially extending groove 44 angularly spaced from groove 42, 43, and circumferentially extending grooves 45, 46, and 47 interconnecting the axially extending grooves, one of these circumferentially extending grooves, 46, being of a narrower width than the other two. Grooves 44 to 47 are provided with bottom serrations of the saw tooth type to be engaged by projection 39, these serrations allowing movement of the projection in the directions indicated by arrows in FIG. 1 but not in the opposite direction. Now, the groove system is related to the angular position of sleeve 17 and washer 26 in such a manner that communication through opening 34 is open when slot 41 in sleeve 17 is opposite to groove 42, 43, and communication through cannula 30 is open when slot 41 in sleeve 17 is opposite to groove 44.

Projections 39 of different types may be provided: one type may be of an angular width which allows the projection to enter groove portion 43 and of an axial length which prevents the projection to enter groove 46; the other type may be of an angular width which prevents the projection to enter groove portion 43 and of an axial length which allows the projection to enter groove 46.

Considering a container 37 having a projection 39 of the first type this may be axially moved over the piston the projection being guided first by groove portion 42 and then by groove portion 43. In the angular position defined by groove portions 42, 43 there is communication through passage 35 from the end face of the piston to opening 34 in cylinder casing 10 and, thus, the air displaced by the piston during the relative movement thereof into the container will escape through said passage. At the upper end of groove portion 43 the container may be rotated in a clockwise direction and thereby sleeve 17 and washer 26 will be moved in the same direction in order to close the communication through passage 35 and to open the communication through passage 32. When cannula 30 is inserted into a vein of a patient blood may now be drawn through the cannula and passage 32 into the container by moving the container axially during relative movement of the piston in the direction out of the container, projection 39 being guided by groove 44. At the lower end of this groove the sleeve and the washer will be returned to their initial angular positions. When projection 39 has reached the groove portion 42 the container may be withdrawn from the piston and the surrounding sleeve and cylinder casing. The blood flow through the cannula now being closed by the valve arrangement described it is possible to replace the container by a new container for drawing a further sample of blood from the patient in the manner described without removing the cannula from the vein.

It is to be noted that a full cycle has to be performed when the projection has entered grooves 45 and 46, respectively, since there is no possibility for projection 39 to move in the counter-clockwise direction or to move upwardly in groove 44. The blocking of upward movement in groove 44 is a precautionary measure in order to prevent air or blood to be displaced into the vein. Grooves 45 and 46 have a slight slope downwardly towards groove 44 in order to create an underpressure in the container when it is rotated from the first angular position to the second angular position, and thus to obtain a suction in the cannula passage before the axial movement of the container along groove 44 will be started.

In case a smaller quantity of blood shall be drawn from the patient a container having the projection of said second type will be used. In that case the projection will have to pass along groove 46 in order to enter groove 44 and thus the axial relative movement of the piston in the container will be reduced.

Claims

I claim:

1. Apparatus suitable for drawing blood samples comprising:

a piston;

a piston rod rigidly connected to and coaxially extending from said piston;

a tubular support means coaxially arranged with respect to and supporting said piston by way of said piston rod;

an inlet tube means supported by said support means and providing a passage communicating with the interior of said support means;

a container having a bore adapted to slideably receive said piston and with said piston defining a receiving chamber;

sealing means extending around the periphery of said piston to sealingly engage said bore;

first and second axially extending passages communicating with said receiving chamber; and

a sleeve means mounted between said piston and said support means for movement relative thereto between first and second positions;

said sleeve means when in said first position facilitating communication of said inlet tube passage with said receiving chamber by way of said first axially extending passage and closing said second axially extending passage;

said sleeve means when in said second position facilitating communication between the environment outside said apparatus and said receiving chamber by way of said second axially extending passage and closing said first axially extending passage.

2. Apparatus as claimed in claim 8 further comprising interengaging means on the container and the sleeve means for providing a releasable engagement between the container and the sleeve means enabling the sleeve means to be manually rotated by the container between said first and second positions.

3. Apparatus as claimed in claim 4 wherein the interengaging means comprises guide track means on the support means and track engaging means on the container allowing for axial displacement of the container in relation to the support means in two different angular positions of the container and rotational movement of the container in relation to the support means between said two different angular positions in at least two axially spaced positions of the container.

4. Apparatus as claimed in claim 3 further comprising means in the guide track means allowing for displacement of the container in one axial direction only in at least one of said angular positions and in one rotational direction only in one of said axially spaced positions and in the opposite rotational direction only in the other one of said axially spaced positions.

5. Apparatus for drawing blood comprising:

a plunger;

support means supporting the plunger at one end thereof;

an inlet pipe for said blood supported by the support means;

a longitudinally extending container, open at one end, of substantially uniform cross sectional area over at least a substantial part of its length from the open end, displaceably receiving the plunger;

means on the plunger sealingly engaging the inner surface of the wall of the container;

said plunger defining a blood receiving passage opening at the inlet pipe and at the other end of the plunger to provide communication between the inlet pipe and said other end of the plunger;

said plunger further defining a vent passage opening opening at said other end of said plunger and at said support means to provide communication between the interior of said container and the surrounding air; and

a sleeve means controlling communication through said blood receiving passage and said vent passage to keep one of these passages open and the other closed, and vice versa;

the container being axially movable on the plunger to form together therewith a cylinder piston type pump adapted when the sleeve means keeps said blood receiving passage open to draw blood through said inlet pipe and said blood receiving passage into said container.