Device for withdrawing body fluids.

(42) Start of patent period: 15.10.1993 (45) Date of issue: 25. 5.1994 (51) Int.Cl.⁵ : A61B 5/14

<td>(56) Documents:</td><td>(73) Patent owner:</td>

<td>EP-A 0223758 EP-A 0352322 EP-A 0376168 WO 88/07351 WO 89/00397</td><td>AVL COMPANY FOR INTERNAL COMBUSTION ENGINES AND MEASUREMENT TECHNOLOGY MBH. PROF.DR.DR.HC HANS LIST A-8020 GRAZ, STYRIA (AT).</td>

<td></td><td>(72) Inventor:</td>

<td></td><td>SKRABAL FALKO DR. GRAZ, STYRIA (AT). KLEINHAPPL ERICH ING. WEINITZEN, STYRIA (AT). LIST HELMUT DIPL.ING. GRAZ, STYRIA (AT).</td>

(54) DEVICE FOR REMOVING BODY FLUIDS (57) A body fluid extraction device comprising a sampling device (1) connected to a hollow needle (6) comprises a storage system (3) having a plurality of separate sample containers arranged on a movable support (4) on. The containers, which are sealed in a gastight manner with a pierceable membrane (5), collect body fluid fractions collected at certain time intervals, with a device (7) connected to a control device (2), with which the hollow needle (6) is successively passed over each of the sample containers (FIG. 4) can be positioned and inserted through the membrane (5) in the sample container. The removal device (1) is designed as a two-lumen cannula (18), one lumen (19) of which via a first connecting line (25) with the hollow needle (6) insertable into the sample container (4) and the other lumen (20) via a second connection line

CQ (26) is connected to a pump (8 ', 21) which is operable by the control device (2). The individual sample containers (4) contain in the unfilled state a gas or gas mixture amount whose volume is less than the volume of the body fluid to be absorbed under atmospheric pressure.

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The invention relates to a device for taking body fluids, for example, blood, Urine or tissue fluid with a withdrawal device, which is connected to a hollow needle, and a storage system, with a plurality of separate sample containers arranged on a movable support, which are gas-tightly sealed with a pierceable membrane and which absorb at certain time intervals collected fractions of the body fluid, wherein a device connected to a control device is provided, with which the hollow needle can be positioned in succession over each of the sample containers and inserted through the membrane into the sample container.

For medical applications, there is often a need for continuous or intermittent recovery of biological fluids, eg, blood, urine, or tissue fluid from humans or animals. It is advantageous to be able to carry out this extraction over 24 hours, ie both during the day and in the night, with an undisturbed sleep being guaranteed especially during the night in order to avoid distortions of the measured values.

For the application described, a new method was specified in WO 89/00397. It is about a roller pump blood in the microliter range, or Also tissue fluid (which is obtained by introducing a perfusion fluid into the tissue) collected in capillary tubes, wherein a valve system allows a temporal assignment of the fluid samples at certain sampling times. This system requires a very elaborate mechanical valve apparatus, which is also associated with a higher weight of the device. In the individual sections of the capillary system, there may be a standstill of the blood column, which favors thrombosis within the system.

A device of the type described above has become known, for example, from EP-A 0 223 758. The apparatus described here for handling small liquid samples has a plurality of sample containers in a rotatable holder, which can be filled via a hollow needle with liquid samples. The hollow needle is connected via a hose with a sampling device not described in detail or Removal needle connected via which the sample is taken. A special device ensures the relative movement between the hollow needle and the sample container to ensure safe insertion into the sample container. To protect the needle whose holder is equipped with a pressure sensor, with axially acting forces which exceed a certain value, further movement of the needle is prevented. When using sample containers which are closed by a membrane, attention is also drawn to the problem of changing internal pressure during sample manipulations. The solution provided in EP-A 0 223 758 problem solving a needle with two holes, which can be made via a pressure equalization, has the disadvantage that also sample parts can escape through this opening. The device or the operator, can be contaminated with the sample.

The object of the invention is, starting from a device of the type mentioned to develop a compact, attachable to the patient for a long time device, with which regardless of the spatial position of the device Fiüssigkeitsproben, such as blood, urine and tissue fluid collected safely and until can be stored for their further use.

This object is achieved according to the invention that the removal device is designed in a manner known per se as a two-lumen cannula, a lumen of the cannula is connected via a first connecting line to the hollow needle which can be inserted into the sample container and the other lumen is connected to a pump via a second connecting line, which can be actuated by the control device, and that the individual sample containers in a known manner in the unfilled state contain a gas or gas mixture amount, the volume of which under atmospheric pressure is smaller than the volume of the body fluid to be absorbed.

In a first, very simple embodiment, in which the sample container are designed rigid walls, so that in the containers a lower compared to the ambient pressure, a pumping unfolding unfolding pressure prevails, it is provided that the connecting line between the two-lumen cannula and the hollow needle has a metering device. About the metering device, such as a metering valve, the desired Fiüssigkeitsstrom can be adjusted. A pump for liquid transport can be omitted in this embodiment, which further simplifies the device.

Another embodiment of the invention, in which the individual sample containers consist of evacuated, deformable vessels, is characterized in that the connecting line between the two-lumen cannula and the hollow needle has a pump, preferably a peristaltic pump, for conveying the body fluid.

In order to store the obtained liquid fractions in the time between removal and subsequent evaluation unadulterated, it is inventively provided that the arranged on the movable support sample container are surrounded by a heat-insulating housing, the lid with

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Is provided openings for the passage of the hollow needle, and in that a temperature sensor connected to the control device and a cooling medium are arranged in the housing.

It is advantageous if the heat-insulating housing together with the sample containers from the rest of the device is removable. While now the collected liquid samples in the heat-insulating housing for further use, eg the evaluation are supplied, a new housing with empty sample containers can be immediately connected to the device and the sampling can be continued without significant interruption.

For example, if the sample is taken in blood vessels, the drug pump may contain heparin, with the heparin exiting the lumen from the lumen immediately being drained away through the other lumen of the needle, causing only small amounts of heparin to enter the body and sustaining blood clotting in the device's lead system is prevented.

In a further development of the invention, it is provided that the device additionally comprises a further medicament pump, preferably a syringe whose drive is in communication with the control device. With this device, studies on the mode of action and temporal concentration of drugs in the blood are possible. About the syringe, a drug can be administered in exactly calculated dosage, so as to gain from the pharmacokinetics of this drug conclusions about body functions.

If samples of tissue fluid are taken directly from the tissue, it is provided in a further embodiment of the invention that the first, leading to the hollow needle connecting line is guided in the suction direction via a peristaltic pump, which also serves as a pressure pump for the second connection line.

The wall of the outer lumen of the two-lumen cannula may have an opening, preferably a plurality of openings.

Finally, it is provided in a further variant of the invention that the wall of the outer lumen of the two-lumen cannula is at least partially formed as a diffusion path.

The invention is explained in more detail below with reference to schematic drawings. 1 shows a device according to the invention, and FIG. 2 shows a variant of the device according to FIG. 1.

The in Fig. 1 shown apparatus for the removal of body fluids has as main components a removal device 1, a control or Data input device 2 and a memory system 3. In the storage system 3 sample containers 4 are arranged in several concentric circles, which are sealed gas-tight with a pierceable membrane 5. A hollow needle 6 connected to the removal device 1 via a connecting line can be successively positioned by means of a device 7 connected to the control device 2 via each of the sample containers 4 and introduced through the membrane 5 into the sample container 4.

The individual sample containers 4 can be designed either rigid-walled, wherein in the containers a reduced compared to the ambient pressure prevails, or consist of evacuated, deformable vessels, in both cases contain the individual sample container 4 in the unfilled state, a gas or gas mixture amount whose volume is less than the volume of the body fluid to be absorbed under atmospheric pressure. The containers must therefore not be vented during filling, whereby the device is operational regardless of its spatial position and leakage of sample components can be prevented.

Between the removal device 1 and the hollow needle 6, a metering device is arranged, which is ralisiert in Fig. 1 by a peristaltic pump 8. Alternatively, in the case of rigid-walled sample containers 4, which exhibit a pumping action due to the lowered internal pressure, a metering valve 28 instead of the peristaltic pump 8 is also conceivable. This metering valve can also be actuated via the control device 2.

As a movable support 9 for the sample container 4, a turntable arranged in a misleading housing 13 is provided in the exemplary embodiment shown, which has a drive 10 in communication with the control device 2. The device 7 for positioning the hollow needle 6 has a first drive device 11 for the radial movement of the hollow needle 6 and a second drive device 12, for the up and down movement of the hollow needle 6. Both drive devices 11 and 12 are acted upon by the control device 2 with signals.

The heat-insulating housing 13 has a closure part or cover 14 with openings 15 through which the hollow needle 6 can pass to the sample containers 4. Only one opening 15 is provided per row of the sample containers arranged in several rows, whereby the cooling losses can be kept low.

Inside the housing 13, a temperature sensor 16 connected to the control device 2 and a cooling medium 17 are arranged. If a permissible maximum temperature is exceeded, the

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Electronics of the control device 2 an optical or audible alarm are triggered. Advantageously, the heat-insulating housing 13 together with the sample containers 4 can be removed from the rest of the device. By attaching a new housing with empty sample containers, the removal of body fluid can be continued without interruption.

In the embodiment according to FIG. 1 the insertable into the sample container 4 hollow needle 6 is connected via a first connection line 25 with the outer lumen 19 of a two-lumen cannula 18 removal device 1, wherein the inner lumen 20 of the cannula 18 is a connecting line 26 to a Medlkamentpumpe, eg a heparin pump 21 has. The drive 22 of the heparin pump is also connected to the control device 2 in connection. Due to the precisely metered amount of heparin, which exits at the top of the two-lumen cannula 18 and is discharged immediately through the negative pressure in the outer lumen 19, the blood coagulation in the leading to the hollow needle 6 connecting line 25 is prevented. To avoid blood clotting, it is also possible to coat the connecting line 25 with a thrombosis-preventing substance.

The device can also be connected via the control device 2 to a further medicament pump 23 together with the drive 24. About the drug syringe can be administered a drug in exactly the desired dosage, so as to gain from the pharmacokinetics of this drug conclusions about the body functions.

Via the control or input unit 2, the patient also has the option of entering a specific code or pressing a key in the event of unforeseen events. As a result, the device is caused by the controller to fill certain sample containers outside the normal row, which can then be evaluated separately. Thereafter, the device automatically returns to its normal operating state.

The embodiment of FIG. 2 is particularly suitable for tissue perfusion, in which - as in the aforementioned WO 89/00397 - a perfusion fluid is introduced into the tissue and pumped out again after a short equilibration phase. The insertable into the sample container 4 hollow needle 6 is connected here via the first connecting line 25 with the lumen 19 of the two-lumen cannula 18, wherein the other lumen 20 of the cannula 18 is connected via the second connecting line 26 with a container 27 for a perfusion fluid. The first connecting line 25 can be guided in the suction direction and the second connecting line 26 in the pumping direction via a single peristaltic pump 8 '. The outer wall of the cannula 18 is provided with openings 29 which increase the contact area to the tissue.

For special applications, the wall of the outer lumen 19 of the cannula 18 may also be partially formed as a diffusion path.