METHOD AND APPARATUS FOR ADDING AN ANTICOAGULANT TO THE BLOOD OF A PATIENT

Abstract

The present invention relates to a method of adding an anticoagulant to the blood of a patient, wherein the addition takes place in the form of a bolus, wherein the bolus application time B depends on the values TBV and CO, with TBV representing the blood volume of the patient and CO the cardiac output of the patient. The present invention furthermore relates to an apparatus for adding a coagulant to the blood of a patient.

Claims

1. A method of adding an anticoagulant to the blood of a patient, wherein the addition takes place in the form of a bolus, characterized in that the bolus application time B depends on the values TBV and CO, with TBV representing the blood volume of the patient and CO the cardiac output of the patient.

2. A method in accordance with claim 1, characterized in that the bolus application time is equal to or greater than the value T=TBV/CO.

3. A method in accordance with claim 1, characterized in that the anticoagulant is applied at the rate Q.sub.hep=V.sub.hep/B, where Q.sub.hep is the volume rate of the anticoagulant and V.sub.hep is the volume of the anticoagulant to be applied.

4. A method in accordance with claim 1, characterized in that the anticoagulant is heparin.

5. A method in accordance with claim 1, characterized in that the addition of the anticoagulant takes place by means of a pump.

6. A method in accordance with claim 1, characterized in that the addition of the anticoagulant takes place into the extracorporeal circuit of a blood treatment machine, in particular of a dialysis machine.

7. A method in accordance with claim 1, characterized in that the addition of the anticoagulant is carried out prior to the blood treatment of the patient, in particular prior to the dialysis treatment of the patient.

8. A method in accordance with claim 1, characterized in that the value TBV and/or the value CO is determined or is read out of a memory prior to the anticoagulant addition.

9. An apparatus for adding an anticoagulant to the blood of a patient, wherein the addition takes place in the form of a bolus, characterized in that the apparatus has means for determining the bolus application time B in dependence on the values TBV and CO, and with TBV representing the blood volume of the patient and CO the cardiac output of the patient, and with the apparatus furthermore having means for administering the anticoagulant within the specific bolus application time B.

10. An apparatus in accordance with claim 9, characterized in that the means for determining the bolus application time are designed such that the relationship BT is satisfied.

11. An apparatus in accordance with claim 9, characterized in that the apparatus has means for determining TBV and/or CO; and/or in that a memory is provided in which the values for TBV and/or CO are stored and which the apparatus can access or which is a component of the apparatus.

12. An apparatus in accordance with claim 9, characterized in that the means for administering the anticoagulant are designed as a pump, with the pump preferably being arranged such that it conveys the anticoagulant into the extracorporeal blood circuit of a blood treatment machine; and/or in that the anticoagulant is heparin.

13. An apparatus in accordance with claim 9, characterized in that the apparatus is a component of a blood treatment machine, preferably of a dialysis machine, or is connected to a blood treatment machine, preferably to a dialysis machine.

14. A blood treatment device, in particular a dialysis machine, having at least one apparatus in accordance with claim 9.

Description

[0042] Further details and advantages of the invention will be explained in more detail with reference to an embodiment shown in the drawing.

[0043] There are shown:

[0044] FIG. 1: a schematic view of a patient connected to a dialysis machine; and

[0045] FIG. 2: a schematic representation of the flows of the arrangement in accordance with FIG. 1.

[0046] As can be seen from FIG. 1, the patient is connected to an extracorporeal blood circuit of a dialysis machine by means of a fistula and the arterial branch of said dialysis machine is marked by the reference symbol A and its venous branch by the reference symbol B. The direction of flow of the blood through the extracorporeal circuit is indicated by arrows.

[0047] The blood moves through the arterial branch A in which the pressure measurement device 10 and the blood pump 20 are located to the dialyzer 30 and from there into the venous branch V. The venous pressure measurement device 40 and the venous drip chamber 50 are located therein. The venous clamp 60 is arranged downstream of the drip chamber 50. The blood moves back to the patient after passing this clamp.

[0048] The blood flow in the dialyzer 30 is marked by the arrow P1 and the dialyzate flow by the arrow P2. The blood and the dialyzate are separated from one another by one or more semipermeable membranes, preferably by a hollow fiber bundle. As can be seen from the arrows P1 and P2, the dialyzer 30 in the embodiment shown is flown through by blood and dialyzate in counter current flow.

[0049] The arrow P3 designates the risk of heparin loss over the membrane of the dialyzer that is in particular present when the heparin has not yet bonded to the proteins of the blood, for instance because it was added at too great a speed or within too short a time.

[0050] Reference symbol F1 marks the fistula flow and the circle in the region of the fistula marks a possible fistula recirculation F2.

[0051] A heparin pump is marked by the reference numeral 70 and, as can be seen from FIG. 1, is connected to the arterial branch A and conveys the heparin into this branch.

[0052] The elements of the blood circuit shown are controlled by a control or regulation unit, not shown, of the dialysis machine.

[0053] Reference symbol CO marks the cardiac output and reference symbol TBV marks the total blood volume of the patient.

[0054] In the example shown here, the blood flow Q.sub.B during the treatment is 300 ml/min and the fistula flow is 1 ml/min.

[0055] Co is furthermore 5 l/in and TBV is 5 l in the example shown.

[0056] The exemplary values and the schematic flows are shown again in FIG. 2.

[0057] In accordance with the above-named formula, T=TBV/CO=1 min.

[0058] In accordance with the invention, the bolus application time B for the anticoagulant thus has to be set to a value of 1 min or more, preferably to 2 min, i.e. the anticoagulant is added to the extracorporeal circuit by means of the pump 70 over a duration of e.g. 2 min. This addition preferably takes place prior to the start of the dialysis treatment.

[0059] The calculation of B takes place in a processing unit of the dialysis machine that accesses a memory in which the values for TBV and CO are stored individually to the patient.

[0060] It is also conceivable that the dialysis machine has a reading device that reads in these value from a patient card or the like.

[0061] After the addition of the anticoagulant, the blood treatment starts by switching on the blood pump 20 and the dialyzate pump, not shown.

[0062] If it is assumed that V.sub.hep is the volume of heparin to be added, there results for the flow rate Q.sub.hep at which the pump 70 conveys

Q.sub.hep=V.sub.hep/B=V.sub.hep/2 min.

[0063] This desired conveying speed is indicated to the pump 70 by the control or regulation unit or by said processing unit of the dialysis machine.