Method of determining a system compressibility value of a medical membrane pump drive

Patent metadata

Field	Value
Publication number	US-2017290971-A1
Application number	US-201515509009-A
Country	US
Kind code	A1
Filing date	Sep 3, 2015
Priority date	Sep 4, 2014
Publication date	Oct 12, 2017
Grant date	—

Abstract

The present invention relates to a method of determining a system compressibility value of a medical membrane pump drive, wherein a first and second pressure level are moved to and a first and second operating parameter value of the membrane pump drive are detected; wherein the system compressibility value is determined on the basis of the detected operating parameter values; and wherein the membrane of the membrane pump drive is supported at a rigid surface during the determination of the system compressibility value.

First claim

1 . A method of determining a system compressibility value of a medical membrane pump drive, wherein a first and a second pressure level are moved to and a first and second operating parameter value of the membrane pump drive is detected, with the system compressibility value being determined on the basis of the detected operating parameter values, characterized in that
the membrane of the membrane pump drive is supported at a rigid surface during the determination of the system compressibility value.

2 . A method in accordance with claim 1 , wherein the first and second pressure levels exceed the maximum counter-pressure of the membrane.

3 . A method in accordance with claim 1 , wherein a pump cassette can be coupled to the membrane pump drive; and wherein the determination of the system compressibility value takes place before the pump cassette has been coupled, with the membrane preferably contacting a receiving surface of a pump cassette receiver.

4 . A method in accordance with claim 1 , wherein a pump cassette can be coupled to the membrane pump drive; and wherein the determination of the system compressibility value takes place with a coupled pump cassette, with the membrane preferably being completely pressed into a pump chamber of the pump cassette and is supported at the rear wall of the pump chamber.

5 . A method in accordance with claim 1 , wherein the determination of the system compressibility value takes place at a vacuum, with the membrane preferably being completely drawn into a drive chamber of the membrane pump drive and contacting a rear wall of the drive chamber.

6 . A method in accordance with claim 1 , wherein an air cushion via which, in normal operation, a pump cassette can be pressed toward a coupling surface of the membrane pump drive is filled to operating pressure before determining the system compressibility value.

7 . A method in accordance with claim 1 , wherein the first pressure level is greater than 50 mbar, preferably greater than 75 mbar, further preferably greater than 100 mbar, further preferably greater than 150 mbar, and/or wherein the first pressure level is smaller than 600 mbar, preferably smaller than 400 mbar, further preferably smaller than 300 mbar, further preferably smaller than 250 mbar; and/or wherein the second pressure level is greater than 50 mbar, preferably greater than 100 mbar, further preferably greater than 200 mbar, further preferably greater than 250 mbar; and/or wherein the second pressure level is smaller than 600 mbar, preferably smaller than 500 mbar, further preferably smaller than 450 mbar, further preferably smaller than 400 mbar; and/or wherein the difference between the first and second pressure levels is greater than 5 mbar, preferably greater than 10 mbar, further preferably greater than 40 mbar, further preferably greater than 80 mbar and/or wherein the difference between the first and second pressure levels is smaller than 500 mbar, preferably smaller than 400 mbar, further preferably smaller than 300 mbar, further preferably smaller than 200 mbar.

8 . A method in accordance with claim 1 , wherein a system compressibility value is determined both at vacuum and at excess pressure.

9 . A method in accordance with claim 1 , wherein the system compressibility value depends on the difference of the operating parameter values that are determined at the first and second pressure levels, with the system compressibility value preferably depending on the difference between the pump positions that the membrane pump drive adopts at the first and second pressure levels and further preferably corresponding to this difference.

10 . A method in accordance with claim 1 , wherein the membrane pump drive has a drive chamber that is closed by the membrane, with the membrane being deflected outwardly out of the drive chamber by excess pressure in the drive chamber and being deflected inwardly into the drive chamber by vacuum in the drive chamber; and/or wherein a pressure sensor is provided that determines the pressure in the drive chamber to move to the first and second pressure levels; and/or wherein the pressure in the drive chamber is preferably produced via a piston-in-cylinder unit connected to the drive chamber; wherein a length sensor is preferably provided that detects the position of the piston as an operative parameter value; and/or wherein the transmission of the pressure onto the membrane preferably takes place hydraulically, with the piston-in-cylinder unit and the drive chamber preferably being filled with hydraulic fluid.

11 . A method of determining an air proportion and/or an air quantity in a medical fluid conveyed by a membrane pump, for which purpose a first and a second pressure level are moved to by a corresponding control of a membrane pump drive of the membrane pump and associated operating parameter values of the membrane pump are detected, with the air proportion and/or the air quantity being determined on the basis of the operating parameter values.

12 . A method in accordance with claim 11 , wherein a system compressibility value of the membrane pump drive is taken into account in the determination of the air proportion and/or of the air quantity; wherein a third and fourth pressure level are moved to for determining the system compressibility value and associated operating parameter values of the pump are detected; wherein the system compressibility value is determined on the basis of the operating parameter values; and wherein the third and fourth pressure levels are preferably equal to the first and second pressure levels.

13 . A method in accordance with claim 11 , wherein a system compressibility value of the membrane pump drive is taken into account in the determination of the air proportion and/or of the air quantity, with the determination of the system compressibility value taking place in accordance with a method wherein a first and a second pressure level are moved to and a first and second operating parameter value of the membrane pump drive is detected, with the system compressibility value being determined on the basis of the detected operating parameter values, characterized in that
the membrane of the membrane pump drive is supported at a rigid surface during the determination of the system compressibility value.

14 . A membrane pump drive having a pressure sensor and having a control, wherein a pump cassette can preferably be coupled to a coupling surface of the membrane pump drive, characterized in that
the control has a function for carrying out a method of determining a system compressibility value in accordance with claim 1 and/or for carrying out a method of determining an air proportion and/or an air quantity in the medical fluid conveyed by the membrane pump drive by determining an air proportion and/or an air quantity in the medical fluid conveyed by the membrane pump, for which purpose a first and a second pressure level are moved to by a corresponding control of the membrane pump drive of the membrane pump and associated operating parameter values of the membrane pump are detected, with the air proportion and/or the air quantity being determined on the basis of the operating parameter values.

15 . A blood treatment machine, in particular a dialysis machine, in particular a peritoneal dialysis machine, having a membrane pump drive in accordance with claim 14 , wherein the blood treatment machine preferably has a pump cassette receiver and/or an air cushion for pressing the pump cassette to a coupling surface of the membrane pump drive.

Assignees

• Fresenius Medical Care Deutschland Gmbh

Inventors

• Hedmann Frank
• Hochrein Torsten

Classifications

• A61M2205/12

  with interchangeable cassettes forming partially or totally the fluid circuit · CPC title

• F04B51/00

  Testing machines, pumps, or pumping installations · CPC title

• A61M1/281 Primary

  Instillation other than by gravity · CPC title

• A61M5/1413

  Modular systems comprising interconnecting elements · CPC title

• A61M2005/14513

  with secondary fluid driving or regulating the infusion · CPC title