Method of operating a blood treatment apparatus, and blood volume monitor and blood treatment apparatus for implementing the method

1. A method of operating a blood treatment apparatus for the extracorporeal blood treatment of a patient (P), comprising:

obtaining a value (RBV) relating to (a) the blood volume at least at one point of time of the blood treatment or (b) a change in the blood volume through at least two points of time of the blood treatment;

obtaining a statement (P a-ex , P v-ex ) concerning (a) a pressure prevailing in a portion of the blood treatment apparatus or in an extracorporeal circulation or (b) a change in the pressure prevailing in the portion of the blood treatment apparatus or in the extracorporeal circulation;

determining the presence of a coincidence between the change in the blood volume and the change in the pressure, the determination being based on (a) the value (RBV) and the statement (P a-ex , P v-ex ) and/or (b) a change in the value (RBV) and a change in the statement (P a-ex , P v-ex ).

2. The method according to claim 1 , wherein the pressure is a blood pressure.

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

outputting a first signal for controlling the blood treatment apparatus, the first signal reflecting (a) the obtained value (RBV) or (b) the change in the obtained value (RBV); and

adapting the first signal to additionally reflect the obtained statement (P a-ex , P v-ex ).

4. The method according to claim 3 , wherein the first signal is for controlling a rate or capacity of ultrafiltration of the blood treatment apparatus.

5. The method according to claim 3 , further comprising:

changing the magnitude of the first signal for controlling the blood treatment apparatus while the first signal reflects (a) the obtained statement (P a-ex , P v-ex ) or (b) the change in the obtained statement (P a-ex , P v-ex ).

6. The method according to claim 5 , wherein the magnitude is changed by adding a pressure-proportional value to the first signal.

7. The method according to claim 3 , further comprising:

outputting a second signal reflecting (a) the obtained statement (P a-ex , P v-ex ) or (b) the change in the obtained statement (P a-ex , P v-ex ).

8. The method according to claim 7 , wherein the second signal is for at least temporarily interrupting a control of the blood treatment.

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

outputting a signal for performing an at least temporarily constant blood treatment.

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

measuring the pressure in the extracorporeal circulation to obtain the statement (P a-ex , P v-ex ).

11. The method according to claim 10 , wherein the pressure is a blood pressure.

12. The method according to claim 10 , wherein pressure is measured in a venous portion of the extracorporeal circulation.

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

measuring the relative blood volume (RBV) to obtain the value (RBV) relating to (a) the blood volume at least at one point of time of the blood treatment or (b) a change in the blood volume through at least two points of time of the blood treatment.

14. A blood volume monitor for monitoring an extracorporeal blood treatment of a patient via a blood treatment apparatus, said blood volume monitor comprising:

means for obtaining a value relating to (a) the blood volume (BV) at least at one point of time of the blood treatment or (b) a change in the blood volume through at least two points of time of the blood treatment; and

means for obtaining a statement (P a-ex , P v-ex ) concerning (a) a pressure prevailing in a portion of the blood treatment apparatus or in an extracorporeal circulation or (b) a change in the pressure prevailing in the portion of the blood treatment apparatus or in the extracorporeal circulation; and

a control unit configured to determine the presence of a coincidence between a change in the blood volume and a change in the pressure, using (a) the value (RBV) and the statement (P a-ex , P v-ex ) and/or (b) a change in the value (RBV) and a change in the statement (P a-ex , P v-ex ).

15. The blood volume monitor according to claim 14 , wherein the pressure is a blood pressure.

16. The blood volume monitor according to claim 15 , further comprising:

a regulation unit configured to output a first signal reflecting the obtained value (RBV) for controlling the blood treatment apparatus; and

means for adapting the first signal to additionally reflect the obtained statement (P a-ex , P v-ex ) concerning (a) the pressure prevailing in a portion of the blood treatment apparatus or in an extracorporeal circulation or (b) the change in the pressure prevailing in the portion of the blood treatment apparatus or in the extracorporeal circulation.

17. The blood volume monitor according to claim 16 , wherein the first signal is for controlling a rate or capacity of ultrafiltration of the blood treatment apparatus.

18. The blood volume monitor according to claim 16 , further comprising:

means for changing the magnitude of the output first signal for controlling the blood treatment apparatus to reflect (a) the obtained statement (P a-ex , P v-ex ) or (b) the change in the obtained statement (P a-ex , P v-ex ).

19. The blood volume monitor according to claim 18 , wherein the magnitude is changed by adding a pressure-proportional value to the first signal.

20. The blood volume monitor according to claim 16 , further comprising:

means for outputting a second signal reflecting (a) the obtained statement (P a-ex , P v-ex ) or (b) the change in the obtained statement (P a-ex , P v-ex ).

21. The blood volume monitor according to claim 20 , wherein the second signal is for at least temporarily interrupting a control of the blood treatment.

22. The blood volume monitor according to claim 14 , further comprising:

means for outputting a signal for performing an at least temporarily constant blood treatment.

23. The blood volume monitor according to claim 15 , further comprising:

a measurement line configured to measure the blood pressure in the extracorporeal circulation.

24. The blood volume monitor according to claim 23 , wherein the measurement line is configured to measure the blood pressure in a venous portion of the extracorporeal circulation.

25. The blood volume monitor according to claim 14 , further comprising:

a measurement unit configured to measure the relative blood volume (RBV).

26. A blood treatment apparatus, comprising:

a blood volume monitor according to claim 14 ; and

a dialysis apparatus configured to accommodate the blood volume monitor.

27. The blood treatment apparatus according to claim 26 , wherein the dialysis apparatus is configured to accommodate a blood tubing system for the extracorporeal blood circulation.

28. The blood treatment apparatus according to claim 26 , further comprising a blood tubing system for the extracorporeal blood circulation.

29. The blood treatment apparatus according to claim 26 , wherein the dialysis apparatus is configured to accommodate a hemodialyzer.

30. The blood treatment apparatus according to claim 26 , wherein the dialysis apparatus includes a hemodialyzer.