Method and device for detecting a leakage in a fluid system of a blood treatment apparatus

• US 6,804,991 B2
• Filed: 01/14/2003
• Issued: 10/19/2004
• Est. Priority Date: 01/15/2002
• Status: Expired due to Term

• Current Assignee: Fresenius Medical Care Deutschland GmbH (Fresenius Medical Care AG)
• Original Assignee: Fresenius Medical Care Deutschland GmbH (Fresenius Medical Care AG)
• Inventors: Ender, Helmuth, Spickermann, Reiner, Balschat, Klaus, Gagel, Alfred
• Primary Examiner(s): Cygan, Michael
• Application Number:
  US10/342,851
• Publication Number:
  US 20030136181A1
• Time in Patent Office: 644 Days
• Field of Search: 73/405.R, 73/13.5, 210/90, 210/644-646, 604/4.01
• US Class Current: 73/40.50R
• CPC Class Codes: A61M 1/16 with membranes
• CPC Class Codes: A61M 1/1601 Control or regulation
• CPC Class Codes: A61M 2205/15 Detection of leaks
• CPC Class Codes: A61M 2205/18 with alarm
• CPC Class Codes: A61M 2205/3331 Pressure; Flow
• CPC Class Codes: A61M 2205/50 with microprocessors or computers

Abstract

In order to detect a leakage in a fluid system of a blood treatment apparatus having an extracorporeal blood circuit, the pressure in the fluid system is measured continuously during a predetermined period of the duration of treatment, and the leak rates are calculated from the change in the pressure at predetermined time intervals of the predetermined period of the duration of treatment. The leakage volume in the predetermined period of the duration of treatment is calculated from the leak rates, and the leakage volume is compared with a predetermined limit value. If the leakage volume is greater than the limit value, this indicates a possible loss of leaktightness in the system. This can be verified with a conventional pressure-holding test. The method and device are characterized by the fact that it is not necessary in principle to interrupt the blood treatment in order to detect a loss of leaktightness.

Claims

1. A method for detecting a leakage in a fluid system of a blood treatment apparatus having an extracorporeal blood circuit, said method comprising:

continuously measuring a pressure in the fluid system during a predetermined period of the duration of the blood treatment;

calculating leak rates from changes in the pressure at predetermined time intervals of the predetermined period of the duration of the blood treatment;

calculating a leakage volume in the predetermined period of the duration of the blood treatment from the leak rates; and

comparing the leakage volume to a predetermined limit value.

2. The method according to claim 1, further comprising:

calculating the changes in the pressure at predetermined time intervals by comparing the pressure in the fluid system to a pressure reference value.

3. The method according to claim 2, wherein the pressure reference value is equal to a pressure value in the fluid system which was measured during a preceding predetermined period of the duration of the blood treatment.

4. The method according to claim 2, wherein the pressure reference value is constant.

5. The method according to claim 2, wherein the pressure reference value is a mean value of a plurality of pressure values measured in an averaging interval.

6. The method according to claim 1, further comprising:

generating an alarm if the leakage volume exceeds the predetermined limit value.

7. The method according to claim 1, further comprising:

if the leakage volume exceeds the predetermined limit value, interrupting the blood treatment and conducting a pressure-holding test in the fluid system in order to check said fluid system for a loss of leaktightness.

8. The method according to claim 7, further comprising:

generating an alarm if the pressure-holding test indicates the loss of leaktightness.

9. The method according to claim 1, wherein the blood treatment apparatus includes a dialyzer which is divided by a semipermeable membrane into a blood chamber and a dialysis fluid chamber, wherein blood flows into the blood chamber via a blood delivery line and flows out of the blood chamber via a blood discharge line, and dialysis fluid flows into the dialysis fluid chamber via a dialysis fluid delivery line and flows out of the dialysis fluid chamber via a dialysis fluid discharge line.

10. The method according to claim 9, wherein the pressure in the fluid system is continuously measured in at least one of the dialysis fluid delivery line upstream of the dialyzer, the dialysis fluid discharge line downstream of the dialyzer, and the blood discharge line downstream of the blood chamber.

11. A device for detecting a leakage in a fluid system of a blood treatment apparatus having an extracorporeal blood circuit, the device comprising:

a controlling and computing unit, the controlling and computing unit comprising;

a means for continuously measuring a pressure in the fluid system during a predetermined period of the duration of the blood treatment;

a means for calculating leak rates from changes in the pressure at predetermined time intervals of the predetermined period of the duration of the blood treatment;

a means for calculating a leakage volume in the predetermined period of the duration of the blood treatment from the leak rates; and

a means for comparing the leakage volume to a predetermined limit value.

12. The device according to claim 11, wherein the means for calculating leak rates are designed to calculate the changes in the pressure by comparing the pressure in the fluid system to a pressure reference value.

13. The device according to claim 12, wherein the pressure reference value is equal to a pressure value in the fluid system which was measured during a preceding predetermined period of the duration of the blood treatment.

14. The device according to claim 12, wherein the pressure reference value is constant.

15. The device according to claim 12, wherein the pressure reference value is a mean value of a plurality of pressure values measured in an averaging interval.

16. The device according to claim 11, further comprising:

an alarm device which generates an alarm if the leakage volume exceeds the predetermined limit value.

17. The device according to claim 11, further comprising:

a means for checking the fluid system for a loss of leaktightness via a pressure-holding test in the fluid system, wherein the controlling and computing unit is designed to interrupt the blood treatment, and the means for checking the fluid system for a loss of leaktightness via a pressure-holding test can be activated to check the fluid system for a loss of leaktightness if the leakage volume exceeds the predetermined limit value.

18. The device according to claim 17, further comprising:

an alarm device which generates an alarm if the pressure-holding test indicates the loss of leaktightness.

19. The device according to claim 11, wherein the blood treatment apparatus includes:

a dialyzer which is divided by a semipermeable membrane into a blood chamber and a dialysis fluid chamber;

a blood delivery line connected to the blood chamber for delivering blood into the blood chamber;

a blood discharge line connected to the blood chamber for removing blood from the blood chamber;

a dialysis fluid delivery line connected to the dialysis fluid chamber for delivering dialysis fluid into the dialysis fluid chamber; and

a dialysis fluid discharge line connected to the dialysis fluid chamber for removing dialysis fluid from the dialysis fluid chamber.

20. The device according to claim 19, wherein the means for continuously measuring a pressure in the fluid system includes a pressure sensor measuring the pressure in at least one of the dialysis fluid delivery line upstream of the dialyzer, the dialysis fluid discharge line downstream of the dialyzer, and the blood discharge line downstream of the dialyzer.