WO1996037150A1

WO1996037150A1 - A device for sampling a specific quantity of organic body fluid

Info

Publication number: WO1996037150A1
Application number: PCT/SE1996/000660
Authority: WO
Inventors: Bengt-Inge Broden
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-05-22
Filing date: 1996-05-21
Publication date: 1996-11-28
Anticipated expiration: 1997-11-22
Also published as: SE9501909L; AU5786596A; SE9501909D0; SE504829C2

Abstract

A device for taking a sample of blood or some other organic body fluid from a patient in a specific volume and transfering this volume to a container, such as a culture bottle. The device includes a body fluid receiving chamber (1) having an inlet (4) and valve means (5, 6) connected to the inlet. In a first position, the valve means functions to connect the inlet (4) to a hose (7) extending from a needle intended for insertion into the patient. The chamber (1) includes a flexible membrane (3) which enables the chamber to be filled with fluid from the inlet (4) without the fluid coming into contact with the air that is therewith pressed out from the chamber. The valve means (5, 6) can be switched to a second position in wich the hose connection is broken and a chamber outlet (8) is opened, this chamber outlet being connectable to the container.

Description

A DEVICE FOR SAMPLING A SPECIFIC QUANTITY OF ORGANIC BODY FLUID

The present invention relates to a device for sampling a specific quantity of blood or some other organic body fluid from a patient, and transferring this sampled quantity to a container, such as a culture bottle.

In the diagnosis of illnesses and pathological changes in internal body organs, among other things, a certain amount of blood or other organic body fluid is taken from the patient for examination. When concerning blood analyses, a certain amount of blood is added to a nutrient solution in a so-called blood cultivating bottle or flask, among other things, and the result of the culture is analyzed after a given period of time has lapsed. Although the invention also applies to analyses of other organic body fluids, the invention will be described below with reference to the sampling of blood for blood cultures, since this method of analysis occurs very frequently. However, the invention is not restricted thereto.

Blood culture samples should be taken in precise predeter¬ mined quantities adapted to the amount of nutrient solution in the culture bottle or flask. In many cases it is necessary to effect both sampling and culturing processes anaerobically. Furthermore, it shall be possible to take a blood sample both simply and quickly and to obtain the predetermined sample quantity automatically, since it may sometimes be necessary to take a blood sample under difficult conditions and in poor lighting. Furthermore, there shall be no danger of nutrient solution or air being introduced into the blood circulation of the patient concerned.

In the most common sampling method used at present, a needle connected to a thin hose is inserted into a patient's vein. The other end of the hose is also connected to a needle which is inserted through a rubber membrane on a blood culture bottle that contains the desired quantity of the nutrient solution in question. Blood is drawn through the needle and into the bottle as a result of the subpressure prevailing therein. The amount of blood thus delivered to the bottle is dependent on the subpressure therein in relation to the surrounding atmospheric pressure, which varies. Consequently, the volume of the blood sample will also vary. A sample volume of 10 ml is normally desired. However, when using equipment of this kind, the volume of blood sampled may vary typically between 6-14 ml, which results in an uncertain and in some cases erroneous analysis response.

Another drawback with the aforedescribed method is that a direct connection is established between the culture bottle and the patient's blood circulation. If the bottle is handled or stored wrongly, it is possible that an overpressure will be generated in the bottle as a result of fermentation, for instance. When a vein is punctured, this overpressure may cause nutrient solution to pass into the vein. There is also the risk on each occasion that air present in the connecting hose will be pressed into the blood circulation.

These problems can be alleviated, by dividing the procedure into two steps. The first step involves taking a desired volume of blood with the aid of a graduated syringe, whereas the second step involves transferring this blood volume to a culture bottle. This method is lengthier than the aforedes¬ cribed method and is more costly, among other things due to the requirement of a disposable syringe.

The main object of the present invention is to provide a simple, inexpensive and reliable device for automatically sampling specific volumes of body fluid which will eliminate the aforesaid drawbacks of known devices, among other things. The present invention is based on the realization that this object can be achieved with a device which in a first stage takes a predetermined sample volume from the patient and in the next stage transfers this volume to a container, such as a culture bottle, in the absence of direct contact between the container and the needle inserted in the patient.

According to the present invention, a device of the kind defined in the first paragraph is characterized in that the device includes a body fluid receiving chamber which has an inlet and a valve means/cuvette connected to the inlet and which when in a first position functions to connect the inlet to a hose extending from a needle intended for insertion into the patient, wherein the chamber includes a flexible membrane which enables the chamber to be filled with fluid from said inlet without the fluid coming into contact with air that is therewith pressed out from the chamber, and wherein the valve means can be adjusted to a second position in which the hose connection is broken and a chamber outlet is opened, said outlet being connectable to a container.

The device thus enables a precise and predetermined volume of body fluid to be sampled and delivered to the container with no risk of "reflux" to the patient.

The membrane is suitably arranged so that the chamber can be filled completely with fluid, wherewith the sample volume is determined by the volume of the chamber. The chamber will preferably have a generally hemispherical shape with a generally flat bottom, wherein the inlet is provided in said bottom and the membrane is sealingly attached at the transi¬ tion between the bottom and the hemispherical top of the chamber.

Other features of the invention will be apparent from the following Claims. The invention will now be described in more detail with reference to an exemplifying embodiment thereof and also with reference to the accompanying drawings, in which

Fig. 1 is a cross-sectional view of an inventive blood sampling device and shows the device while taking a blood sample from a patient; and

Fig. 2 is a cross-sectional view of the device shown in Fig. 1 during the transfer of the blood sample to a culture bottle.

The illustrated device comprises a hemispherical receiving chamber 1 having a flat bottom 2. A schematically illustrated membrane 3 made of thin rubber material or plastic material is welded sealingly around the transition between the bottom 2 and the hemispherical top 1. The membrane 3 divides the chamber 1 into two mutually separated parts. In its initial starting position, the membrane 3 lies folded or pleated on the bottom 2. The area of the membrane shall be at least equally as large as the internal area of the hemispherical top 1. The hemispherical top 1 may be welded at the periphery of the bottom 2 together with the membrane 3.

The bottom 2 is provided with an inlet 4 from a valve housing 5 in which a plug tap is rotatably mounted. In Figure 1, the plug 6 is in a position in which the inlet 4 is connected with a thin plastic hose 7 which is connected at one end to the valve chamber 5 and is provided at its other end with a needle (not shown) intended for insertion into a patient's vein.

The bottom 2 is also provided with an outlet 8, which is closed in the illustrated position of the plug 6 in Fig. 1. Provided at the highest point of the hemispherical top 1 is an outlet 9 which communicates with the surrounding atmo¬ sphere. The valve chamber 5 has an outlet 10 to which a needle 11 is connected. The needle can be used to transfer sample fluid from the chamber 1 to a culture bottle 12 which typically includes a rubber membrane that can be penetrated by the needle 11. The device is suitably controlled in this regard with the aid of a sleeve 13 placed over the neck of the bottle.

The described device functions in the following manner.

With the plug 6 in the position shown in Fig. 1, blood will flow from a needle (not shown) inserted into a patient's vein, through the hose 7 and into the chamber 1 via the inlet 4. A normal vein pressure is about 20 mm Hg. The inflowing blood therewith lifts the membrane 3 up towards and against the inner surface of the hemispherical top 1, and air present in the chamber will be displaced and depart through the outlet 9 without coming into contact with the blood that flows in beneath the membrane 3. The chamber 1 may have a volumetric capacity of 10 ml for instance, wherewith it will be known with certainty that the chamber contains a sample volume of 10 ml when the membrane 3 reaches the inner surface of the hemispherical top.

Subsequent to filling the chamber 1, the plug 6 is set to the position shown in Fig. 2 with the aid of a plug grip 16, so as to close the inlet 4 to the chamber 1 while bringing the outlet 8 into connection with the outlet 10 connected to the needle 11, through the medium of a passage 14 in the valve slide 6.

The subpressure that prevails in the bottle 12, which subpressure may be well taken, will cause the blood to be drawn from the chamber 1 and into the bottle 12, in which it is mixed with intended nutrient solution. The whole of the sampling process takes place without the blood coming into contact with the ambient air. Neither is there any risk of air or nutrient solution being pressed back to the patient, since no direct connection between the bottle 12 and the hose 7 is possible. Furthermore, a precise volume of sample is always obtained, irrespective of the ambient pressure and without the person taking the sample needing to read-off the sample against a scale.

The vein pressure of old, sick and infirm persons in particu¬ lar may be so low as to be unable to fill the chamber 1. As shown in Fig. 1, there may be provided in this regard a compressible rubber ball 15 or like device which is connected to the outlet 9 and which when expanding generates a given subpressure in the chamber 1, enabling the chamber to be filled with blood. The ball 15 is compressed prior to being connected to the outlet 9. However, there can be no risk of air being pressed into the patient's vein even if the ball 15 is compressed when fitted, since the membrane 3 will therewith act as a "check valve" and prevent air from passing out through the inlet 4. Naturally, the ball 15 can be replaced with some other device capable of creating a subpressure in the chamber 1.

The ball 15 can also be used in the second stage shown in Fig. 2 for safe transfer of all blood in the chamber 1 to the bottle 12. In this case, the ball is used to generate an overpressure in the chamber 1, as the ball is compressed.

The aforedescribed device can be used suitably in the assembled state shown in Fig. 2. However, the device may alternatively be used for separate sampling of a body fluid in accordance with the Fig. 1 illustration, whereafter the sample is transferred to a bottle 12 in accordance with Fig. 2 in a second stage of the sampling process. In this latter case, the bottle need not be fitted to the device at the time of taking the sample. According to the aforegoing, the volume of the sample is determined by the volumetric capacity of the hemispherical chamber 1. Alternatively, the area of the membrane 3 may be smaller than the inner surface of the chamber 1, in which case the volume is determined by the area of the membrane. In this case, the membrane will preferably be essentially non-elastic at the pressure in question.

The invention has been described in the aforegoing with reference to blood cultures. As mentioned in the introduc¬ tion, however, the device can also be used for sampling other organic body fluids for different analyses. Furthermore, the sampled volume of body fluid may be transferred to a contain¬ er other than a bottle 12, in which case the needle 11 may be replaced with some other suitable transfer means.

The device can also be modified in several other respects within the scope of the following Claims. For instance, the valve means 5, 6 may have any desired construction and may optionally be replaced with two separate valves, which are suitably forcibly controlled relative to one another. The shape of the chamber 1 can also be varied in accordance with requirements.

Claims

1. A device for taking a specific volume of blood or some other organic body fluid from a patient and transferring said volume to a container (12) such as a culture bottle, charac¬ terized in that the device includes a body fluid receiving chamber (1) having an inlet (4), valve means (5, 6) connected to the inlet and which when in a first position functions to connect the inlet (4) to a hose (7) extending from a needle intended for insertion into the patient, that the chamber (1) is provided with a flexible membrane (3) which enables the chamber to be filled with fluid from said inlet (4) without the fluid coming into contact with the air that is therewith pressed out of the chamber; and in that said valve means (5, 6) can be switched to a second position in which the connec¬ tion with the hose (7) is broken and a chamber outlet (8) is opened, said outlet being connectable to said container (12) .

2. A device according to Claim 1, characterized in that the membrane (3) is arranged to enable the chamber (1) to be filled completely with fluid, wherein the sample volume is determined by the volumetric capacity of the chamber.

3. A device according to Claim 1 or Claim 2, characterized in that the chamber (1) has a generally hemispherical shape with a generally flat bottom (2) ; and in that the inlet (4) is provided in said bottom and the membrane (3) is sealingly attached at the transition between said bottom and said generally hemispherical top of said chamber.

4. A device according to Claim 3, characterized in that the membrane (3) is comprised of a thin rubber or plastic material and has an area which corresponds at least to the inner surface area of the generally hemispherical top (I) of the chamber (1) .

5. A device according to any one of Claims 1-4, character¬ ized in that when in its second position the valve means (5, 6) connects the outlet (8) with an outlet (10) from the valve means (5, 6) , wherein a needle (11) or a corresponding device can be connected to said outlet (10) to enable the sample volume to be transferred from the chamber (1) to a desired container (12) .

6. A device according to any one of Claims 1-5, character- ized in that the chamber (1) is provided on the side of said membrane (3) opposite said inlet (4) with an outlet (9) through which the chamber (1) communicates with the surround¬ ing atmosphere.

7. A device according to Claim 6, characterized in that the device includes a flexible ball (15) or some other corre¬ sponding device that can be connected to the outlet (9) which communicates with the atmosphere so as to enable a sub¬ pressure to be generated in said chamber (1) .