Flow balancing devices, methods, and systems

Patent metadata

Field	Value
Publication number	US-12226557-B2
Application number	US-202318508533-A
Country	US
Kind code	B2
Filing date	Nov 14, 2023
Priority date	Oct 10, 2014
Publication date	Feb 18, 2025
Grant date	Feb 18, 2025

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 system for performing a medical treatment, the system comprising:
a controller;
one or more controllable valve actuators;
a first pump;
a second pump, wherein the controllable valve actuators, the first pump and the second pump are controlled by the controller;
the first pump being controlled to regulate a flow toward a patient interface device and the second pump a being controlled to regulate a flow from the same patient interface device;
the patient interface device being a device that is separate from the system and interfaces with a patient fluid compartment including at least one of a dialyzer, a hemofilter, a hemodiafilter, an ultrafilter, and a plasmapheresis device;
the controller being configured to regulate a speed of the first and second pumps to achieve a predefined net removal of fluid from the patient interface device during a treatment interval;
the controller being further configured to control the control valve actuators to switch between a first position that configures a fluid circuit, when attached to said controllable valve actuators, in a bypass configuration which defines a bypass flow path that bypasses the patient interface device, and a second position which defines a flow path into and out of the patient interface device;
a pressure transducer connected to convey pressure signals to the controller, the pressure signals indicating pressure in the bypass flow path;
the controller being programmed to calculate and store flow correction data representing a correction to be applied to a rate of flow of said at least one of the first and second pumps responsively to said pressure signals; and
the controller being further programmed to modify a flow rate of said at least one of the first and second pumps responsively to said flow correction data, wherein
the system further comprises a third pump that pumps fluid into the patient interface device during a treatment, the third pump being coupled to a synchronization mechanism that causes the first and third pumps to pump equal amounts of fluid per unit time during the medical treatment.

2. The system of claim 1 , wherein a diverted flow in the bypass configuration flows between the first and second pumps through a fluid accumulator connected to a pressure sensor that outputs said pressure signals.

3. The system of claim 2 , wherein the fluid accumulator is configured such that pressure increases as fluid fills said fluid accumulator, whereby a difference in flow rates of the first pump and the second pump results in an increasing or decreasing pressure.

4. The system of claim 3 , wherein the fluid accumulator has a residual volume of fluid to permit a measurement of a pressure change caused by a net removal or a net addition of fluid from or to said fluid accumulator.

5. The system of claim 1 , wherein the first pump includes a peristaltic pump.

6. The system of claim 1 , wherein the fluid circuit includes a disposable plastic tubing set and at least one control valve, the control valve including a tubing junction that interfaces with one or more pinch clamps to form selectable flow paths, the one or more pinch clamps being permanent reusable elements that pinch respective portions of the tubing set.

7. The system of claim 1 , further comprising a blood circuit that interfaces with the patient interface device and, through the patient interface device, to the fluid circuit and wherein a diverted flow in the bypass configuration flows through a flow path between the first and second pumps through a fluid accumulator connected to a pressure sensor that outputs said pressure signals, wherein a fluid circuit portion connected to the patient interface device is separate from said flow path.

8. The system of claim 1 , wherein the controller is connected to a user interface and programmed to accept and store ultrafiltration data representing a target net ultrafiltration, wherein the controller is further programmed to control flow through said at least said one of said first and second pumps responsively to said ultrafiltration data.

9. A method of regulating a balanced flow of fluids, comprising:
in a system having first and second fluid channels each with at least one respective pump for each of said first and second fluid channels, using a controller to control a rate of pumping of one or more of said respective pumps to establish flows in the first and second fluid channels of equal volume flow rate based on calibration data stored in said controller;
the first and second fluid channels connecting to a fluid handling device in which a ratio of flow rates of an entering flow to said fluid handling device and a leaving flow from said fluid handling device is maintained by said controller;
using the controller, temporarily establishing a flow from said first fluid channel to said second fluid channel through a test flow branch with a pressure sensor and receiving a signal of a test branch pressure in said test flow branch at said controller; and
in response to said test flow branch pressure signal, using the controller, adjusting said calibration data; and
thereafter, using said controller, adjusting one or more of said respective pumps according to the calibration data adjusted by said adjusting,
wherein the respective pumps are of a type that produce pressure pulses at regular intervals during pumping, the respective pumps being selected such that the pressure pulses of pumps flowing into and out of the test flow branch differ by at least a factor of two at pumping rates that occur times other than at times of said temporarily establishing.

10. The method of claim 9 , wherein said controller receives a local pressure signal from upstream and/or downstream of at least one of said respective pumps, said adjusting being responsive to both said test flow branch pressure signal and said local pressure signal.

11. The method of claim 10 , wherein said receiving the local pressure signal includes receiving the local pressures upstream and downstream of said at least one of said respective pumps.

12. The method of claim 9 , wherein the controller controls a valve that selectively permits flow through said test flow branch and said controller automatically selects a time of said temporarily establishing.

13. The method of claim 9 , wherein the controller controls a valve that selectively permits flow through said test flow branch and said controller automatically selects multiple instances of said temporarily establishing.

14. The method of claim 9 , wherein the fluid handling device is a blood treatment device.

15. The method of claim 14 , wherein the blood treatment device is a dialyzer or a hemofilter and replacement fluid source.

16. The method of claim 9 , wherein said respective pumps are peristaltic pumps and pumping tube segments of no one of the respective pumps responsible for said entering flow has an inner diameter the same as a pumping tube segment inner diameter of a one of said respective pumps responsible for said leaving flow.

17. The method of claim 9 , wherein said respective pumps are peristaltic pumps and a number of rollers for no one of the respective pumps responsible for said entering flow is the same as the number of the rollers of a one of said respective pumps responsible for said leaving flow.

Assignees

• Nxstage Medical Inc

Inventors

• Burbank Jeffrey H
• Treu Dennis M
• Rubery Jr Daniel Joseph
• 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

• A61M2205/502

  User interfaces, e.g. screens or keyboards · CPC title

• A61M2205/3368

  Temperature · CPC title

• A61M2205/3365

  Rotational speed · CPC title

• A61M2205/15

  Detection of leaks · CPC title

• A61M1/34

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