Device and method for detecting the recirculation during an extracorporeal blood treatment

Patent metadata

Field	Value
Publication number	US-9616164-B2
Application number	US-201615012010-A
Country	US
Kind code	B2
Filing date	Feb 1, 2016
Priority date	Sep 21, 2012
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

A device and method for detecting recirculation for an extracorporeal blood treatment apparatus and an apparatus with a device for detecting recirculation are based on targeted haemodilution by administration of a substituate bolus, causing a pressure change in venous and arterial branches of the extracorporeal circuit due to a viscosity change of flowing fluid. Recirculation is detected based on detection of the pressure change. The device includes a control unit cooperating with a device for conveying blood and a device for supplying substituate. The control unit provides an operating mode for detecting recirculation, in which blood flow rate is reduced during administration of a substituate bolus. With simultaneous substituate bolus administration and reduction of blood flow rate, the composition of fluid flow is optimized for detection of recirculation, so that fairly large pressure changes result in venous and arterial branches, thereby improving sensitivity and reliability of the measurement method.

First claim

What is claimed is:

1. A device for detecting recirculation for an extracorporeal blood treatment apparatus, the extracorporeal blood treatment apparatus comprising an extracorporeal blood circuit with an arterial blood line, which leads to a first chamber of a dialyser or filter divided by a membrane into the first chamber and a second chamber, and a venous blood line, which leads away from the first chamber of the dialyser or filter, a fluid system, which comprises the second chamber of the dialyser or filter, a device for conveying blood at a preset blood flow rate Q b through the arterial blood line into the first chamber of the dialyser or filter and through the venous blood line from the first chamber of the dialyser or filter, and a device for supplying substituate to the blood at a preset substituate rate Q s in the arterial blood line upstream of the dialyser or filter, the device for detecting the recirculation comprising:
a measuring unit adapted for measuring pressure in the extracorporeal circuit in the arterial and/or venous blood line;
an evaluation unit adapted for detecting the recirculation based on the pressure measurement; and
a control unit cooperating with the device for conveying blood and the device for supplying substituate, the control unit being adapted, in an operating mode for detecting the recirculation, to control the device for conveying blood such that in a preset time interval, a preset first blood flow rate Q b1 is reduced to a preset second blood flow rate Q b2 , and to control the device for supplying substituate such that in the preset time interval, substituate is fed at the preset substituate rate Q s to the blood in the arterial blood line upstream of the dialyser or filter,
wherein the evaluation unit is adapted to monitor the pressure measured by the measuring unit in the arterial and/or venous blood line for a change in the pressure and to calculate a ratio between an amount of the change in the pressure measured by the measuring unit in the arterial blood line and an amount of the change in the pressure measured in the venous blood line.

2. The device according to claim 1 , wherein the evaluation unit is adapted to generate a control signal signalling a presence of the recirculation when a pressure increase is detected in the arterial blood line.

3. The device according to claim 1 , wherein the evaluation unit is adapted to generate a control signal signalling a presence of the recirculation when a pressure reduction is detected in the venous blood line.

4. The device according to claim 1 , further comprising:
an optical and/or acoustic signal unit adapted to receive a control signal of the evaluation unit, said signal unit being adapted to generate an acoustic and/or optical signal when the signal unit receives the control signal from the evaluation unit.

5. The device according to claim 1 , wherein the control unit is adapted to control the device for supplying substituate in the preset time interval in the operating mode for detecting the recirculation such that a difference between the preset substituate rate Q s and a difference between the first blood flow rate Q b1 and the second blood flow rate Q b2 corresponds to a specific value.

6. The device according to claim 5 , wherein the specific value is zero.

7. The device according to claim 1 , further comprising:
an actuation unit provided for the control unit, the actuation unit being adapted such that, after actuation of an actuation element, the control unit selects the operating mode for detecting the recirculation, in which the device for conveying blood and the device for supplying substituate are controlled.

8. An extracorporeal blood treatment apparatus, comprising:
an extracorporeal blood circuit with an arterial blood line, which leads to a first chamber of a dialyser or filter divided by a membrane into the first chamber and a second chamber, and a venous blood line, which leads away from the first chamber of the dialyser or filter,
a fluid system, which comprises the second chamber of the dialyser or filter,
a device for conveying blood at a preset blood flow rate Q b through the arterial blood line into the first chamber of the dialyser or filter and through the venous blood line from the first chamber of the dialyser or filter,
a device for supplying substituate to the blood at a preset substituate rate Q s in the arterial blood line upstream of the dialyser or filter, and
the device for detecting the recirculation according to claim 1 .

9. A method for detecting recirculation for an extracorporeal blood treatment apparatus, the extracorporeal blood treatment apparatus comprising an extracorporeal blood circuit with an arterial blood line, which leads to a first chamber of a dialyser or filter divided by a membrane into the first chamber and a second chamber, and a venous blood line which leads away from the first chamber of the dialyser or filter, a fluid system, which comprises the second chamber of the dialyser or filter, a device for conveying blood at a preset blood flow rate Q b through the arterial blood line into the first chamber of the dialyser or filter and through the venous blood line from the first chamber of the dialyser or filter, a device for supplying substituate to the blood at a preset substituate rate Q s in the arterial blood line upstream of the dialyser or filter, wherein pressure in the extracorporeal blood circuit is measured in the arterial and/or venous blood line and detection of the recirculation takes place based on the pressure measurement, the method comprising:
in an operating mode for detecting the recirculation,
reducing a preset first blood flow rate Q b1 to a preset second blood flow rate Q b2 in a preset time interval,
supplying substituate at the preset substituate rate Q s to the blood in the arterial blood line upstream of the dialyser or filter in the preset time interval,
monitoring the pressure measured by a measuring unit in the arterial and/or venous blood line for a change in the pressure, and
detecting a presence of the recirculation by calculating a ratio between an amount of the change in the pressure measured by the measuring unit in the arterial blood line and an amount of the change in the pressure measured in the venous blood line.

10. The method according to claim 9 , wherein the pressure measured by the measuring unit in the arterial blood line is monitored for an increase in the pressure, wherein the presence of the recirculation is detected when there is an increase in pressure.

11. The method according to claim 9 , wherein the pressure measured by the measuring unit in the venous blood line is monitored for a reduction in the pressure, wherein the presence of the recirculation is detected when there is a reduction in pressure.

12. The method according to claim 9 , further comprising:
generating an acoustic and/or optical signal when there is a change in pressure.

13. The method according to claim 9 , further comprising:
in the operating mode for detecting the recirculation, the substituate rate Q s is selected, at which a difference between the preset substituate rate Q s and a difference between the first blood flow rate Q b1 and the second blood flow rate Q b2 corresponds to a specific value.

14. The method according to claim 13 , wherein the specific value is zero.

Assignees

• Fresenius Medical Care Deutschland Gmbh

Inventors

• Nuernberger Thomas

Classifications

• A61M1/3653 Primary

  Interfaces between patient blood circulation and extra-corporal blood circuit · CPC title

• A61M2205/3334

  Measuring or controlling the flow rate · CPC title

• A61M1/3656 Primary

  Monitoring patency or flow at connection sites; Detecting disconnections · CPC title

• B01D61/28

  Apparatus therefor · CPC title

• A61M1/342

  Adding solutions to the blood, e.g. substitution solutions (for preventing coagulation A61M1/3672) · CPC title