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 comprising adding an anticoagulant bolus to blood of a patient over a bolus addition time B, wherein the bolus addition time B depends on TBV and CO, with TBV representing total blood volume of the patient and CO representing cardiac output of the patient.

2. The method in accordance with claim 1, wherein the bolus addition time B is equal to or greater than T, where T=TBV/CO.

3. The method in accordance with claim 1, wherein the anticoagulant bolus is added at a volume V.sub.hep and a rate Q.sub.hep, where Q.sub.hep=V.sub.hep/B.

4. The method in accordance with claim 1, wherein the anticoagulant bolus is heparin.

5. The method in accordance with claim 1, wherein addition of the anticoagulant bolus takes place by a pump.

6. The method in accordance with claim 1, wherein addition of the anticoagulant bolus takes place into an extracorporeal circuit of a blood treatment machine.

7. The method in accordance with claim 1, wherein addition of the anticoagulant bolus is carried out prior to a blood treatment of the patient.

8. The method in accordance with claim 1, wherein at least one of TBV and CO is determined or is read out of a memory prior to the anticoagulant bolus addition.

9. The method of claim 6, wherein the blood treatment machine is a dialysis machine.

10. The method of claim 7, wherein the blood treatment is a dialysis treatment.

11. A blood treatment machine comprising: at least one apparatus for adding an anticoagulant bolus to the blood of a patient, a processing unit that is programmed to determine a bolus addition time B in dependence on TBV and CO, with TBV representing total blood volume of the patient and CO representing cardiac output of the patient, a memory is provided in which the values for TBV and/or CO are stored, and means for administering the anticoagulant bolus within the bolus addition time B.

12. The blood treatment machine in accordance with claim 11, wherein the bolus addition time B is determined by the processing unit such that B>T is satisfied, where T=TBV/CO.

13. The blood treatment machine in accordance with claim 11, wherein the means for administering the anticoagulant are designed as a pump, with the pump being arranged such that the pump conveys the anticoagulant into an extracorporeal blood circuit of the blood treatment machine.

14. The blood treatment machine in accordance with claim 11, wherein the blood treatment machine is a dialysis machine.

Description

(1) Further details and advantages of the invention will be explained in more detail with reference to an embodiment shown in the drawing.

(2) There are shown:

(3) FIG. 1: a schematic view of a patient connected to a dialysis machine; and

(4) FIG. 2: a schematic representation of the flows of the arrangement in accordance with FIG. 1.

(5) 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 V. The direction of flow of the blood through the extracorporeal circuit is indicated by arrows.

(6) 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.

(7) 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.

(8) 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.

(9) Reference symbol F1 marks the fistula flow and the circle in the region of the fistula marks a possible fistula recirculation F2.

(10) 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.

(11) The elements of the blood circuit shown are controlled by a control or regulation unit, not shown, of the dialysis machine.

(12) Reference symbol CO marks the cardiac output and reference symbol TBV marks the total blood volume of the patient.

(13) 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.

(14) CO is furthermore 5 l/in and TBV is 5 l in the example shown.

(15) The exemplary values and the schematic flows are shown again in FIG. 2.

(16) In accordance with the above-named formula, T=TBV/CO=1 min.

(17) 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.

(18) 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.

(19) It is also conceivable that the dialysis machine has a reading device that reads in these value from a patient card or the like.

(20) After the addition of the anticoagulant, the blood treatment starts by switching on the blood pump 20 and the dialyzate pump, not shown.

(21) 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.

(22) 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.