Flow balancing devices, methods, and systems

Patent metadata

Field	Value
Publication number	US-10835659-B2
Application number	US-201916381369-A
Country	US
Kind code	B2
Filing date	Apr 11, 2019
Priority date	Oct 10, 2014
Publication date	Nov 17, 2020
Grant date	Nov 17, 2020

Abstract

The disclosed subject matter relates to extracorporeal blood processing or other processing of fluids. Volumetric fluid balance, a required element of many such processes, may be achieved with multiple pumps or other proportioning or balancing devices which are to some extent independent of each other. This need may arise in treatments that involve multiple fluids. Safe and secure mechanisms to ensure fluid balance in such systems are described.

First claim

The invention claimed is:

1. A method of maintaining a predefined ratio of flow rates in a first channel and a second channel, the method comprising:
flowing a fluid through the first channel with a first peristaltic pump;
flowing the fluid through the second channel with a second peristaltic pump;
connecting the first channel and the second channel temporarily by a third channel to create a continuous flow between the first channel and the second channel;
measuring during a measurement time period a static pressure of the third channel carrying the continuous flow temporarily generated in the connecting; and
adjusting calibration data of one or both of the first peristaltic pump and the second peristaltic pump responsively to a result of the measuring the static pressure, wherein
the first peristaltic pump has a first pulsation frequency at a rate of the continuous flow,
the second peristaltic pump has a second pulsation frequency at the rate of the continuous flow,
the first pulsation frequency and the second pulsation frequency produce a superposed beat frequency due to superposition of their respective pulsations, and
the measurement time period is multiple times longer than a period of the superposed beat frequency.

2. The method of claim 1 , wherein the connecting, measuring, and adjusting are done automatically by a programmable controller, the method further comprising adjusting a speed of said one or more respective pumps in response to said calibration data.

3. The method of claim 1 , further comprising:
adjusting one or both of the first peristaltic pump and the second peristaltic pump to a flow rate that produces beats at the superposed beat frequency with the period multiple times shorter than the measurement time period; and
sampling said static pressure multiple times over said measurement time period, wherein
the first peristaltic pump and the second peristaltic pump have different ratios of flow rate to pulsation frequencies.

4. The method of claim 3 , wherein the first peristaltic pump and the second peristaltic pump have differences in one or a combination of tubing inner diameter or number of rollers of a peristaltic pump rotor.

5. The method of claim 1 , wherein one or both of the first and second channels includes at least two fluid lines.

6. The method of claim 5 , wherein the connecting, measuring, and adjusting are done automatically by a programmable controller, the method further comprising adjusting a speed of said one or more respective pumps in response to said calibration data.

7. The method of claim 4 , wherein the first peristaltic pump and the second peristaltic pump have different suction side head pressure.

8. The method of claim 1 , wherein the first and second channels are, at times other than said measuring, connected by a controller to a medical treatment device for supply and withdrawal of treatment fluid.

9. The method of claim 8 , wherein the medical treatment device includes a renal replacement therapy system and the treatment fluid includes dialysate or electrolyte.

10. A method of maintaining a predefined ratio of flow rates in a first channel and a second channel, the method comprising:
flowing a fluid through the first channel with a first peristaltic pump;
flowing the fluid through the second channel with a second peristaltic pump;
connecting the first channel and the second channel temporarily by a third channel to create a continuous flow between the first channel and the second channel;
measuring during a measurement time period a static pressure of the third channel carrying the continuous flow temporarily generated in the connecting; and
adjusting calibration data of one or both of the first peristaltic pump and the second peristaltic pump responsively to a result of the measuring the static pressure, wherein
the first peristaltic pump has a first pulsation frequency at a rate of the continuous flow,
the second peristaltic pump has a second pulsation frequency at the rate of the continuous flow,
the first pulsation frequency and the second pulsation frequency produce a superposed beat frequency due to superposition of their respective pulsations, and
the measurement time period is multiple times shorter than a period of the superposed beat frequency.

11. The method of claim 10 , wherein the connecting, measuring, and adjusting are done automatically by a programmable controller, and the method further comprises adjusting a speed of said one or more respective pumps in response to said calibration data.

12. The method of claim 10 , wherein the measuring includes sampling said static pressure multiple times over said measurement time period.

13. The method of claim 10 , wherein the first peristaltic pump and the second peristaltic pump have different ratios of flow rate to pulsation frequencies.

14. The method of claim 13 , wherein the first peristaltic pump and the second peristaltic pump have different ratios as a result of having differences in one or a combination of tubing inner diameter or number of rollers of a peristaltic pump rotor.

15. The method of claim 14 , wherein one or both of the first and second channels includes at least two fluid lines.

16. The method of claim 15 , wherein the connecting, measuring, and adjusting are done automatically by a programmable controller, and the method further comprises adjusting a speed of the first peristaltic pump and the second peristaltic pump in response to said calibration data.

17. The method of claim 10 , wherein the first and second channels are, at times other than at times that said continuous flow is established by said controller, connected by the controller to a medical treatment device for supply and withdrawal of treatment fluid.

18. A method of controlling a rate of ultrafiltration/infusion in an extracorporeal blood circuit, comprising:
pumping treatment fluid through blood treatment device using one or more peristaltic pumps;
pumping blood through the blood treatment device using two pumps whose rates of flow are controlled by a controller to achieve a predefined volume of ultrafiltration by the end of a treatment interval;
at times during a treatment, flowing blood between the two pumps and receiving a pressure signal representative of the relative rates of flow between the two pumps; and
based on the pressure signal, revising calibration data used to control the rates of flow to achieve the predefined volume, wherein
the revising includes changing a pumping rate of one of the two pumps responsively to an average of the pressure signal to achieve an unchanging pressure and using data indicating a rotation rate of the one of the two pumps when the unchanging pressure is achieved to revise the calibration data.

19. The method of claim 18 , wherein the two pumps are peristaltic pumps.

20. The method of claim 18 , wherein the receiving a pressure signal includes receiving a transient static pressure generated by unequal flows of the two pumps to and from a branch channel connecting the two pumps.

21. A method of controlling a balanced flow in a medical treatment, comprising:
using at least two pumps, flowing fluid into and out of a fluid management component over the course of a treatment interval and controlling rates of flow of said at least two pumps to meet a target net flow into or out of the fluid management component at an end of the treatment interval;
at calibration times during the treatment interval, interconnecting the at least two pumps and

Assignees

• Nxstage Medical Inc

Inventors

• Burbank Jeffrey H
• Treu Dennis M
• Rubery Jr Daniel J
• Newell Scott W
• Brugger James M
• Schnell William J
• Weigel William K
• White Steven A
• Wyeth Mark T
• James Jerome
• Desouza David
• Turk Jr Joseph E
• Casey Garrett

Classifications

• A61M1/3607

  Regulation parameters · CPC title

• A61M1/34

  Filtering material out of the blood by passing it through a membrane, i.e. hemofiltration or diafiltration · CPC title

• A61M1/3403

  Regulation parameters · CPC title

• A61M1/3448

  by mechanically linked pumps in both ultra-filtrate and substitution flow line · CPC title

• A61M1/3437

  downstream of the filter, e.g. post-dilution with filtrate · CPC title