# US 10,869,958 B2 · Flow balancing devices, methods, and systems

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- Number: US 10,869,958 B2
- Document ID: US10869958B2
- Status: Granted
- Kind: B2
- Application number: 16/381,363
- Filed: 2019-04-11
- Published: 2019-08-08
- Granted: 2020-12-22
- Earliest claimed: 2014-10-10
- Assignees: NxStage Medical, Inc.
- Applicants: NxStage Medical, Inc.
- Inventors: Jeffrey H. Burbank; Dennis M. Treu; Daniel J. Rubery, Jr.; Scott W. Newell; James M. Brugger; William J. Schnell; William K. Weigel; Steven A. White; Mark T. Wyeth; Jerome James; David Desouza; Joseph E. Turk, Jr.; Garrett Casey
- Web page: https://patentgrep.com/patent/US10869958B2

## CPC

- A61M 1/1605: {Physical characteristics of the dialysate fluid}
- A61M 1/14: Dialysis systems; Artificial kidneys; Blood oxygenators (semi-permeable membranes characterised by the material, manufacturing processes therefor B01D71/00){; Reciprocating systems for treatment of body fluids, e.g. single needle systems for hemofiltration or pheresis}
- A61M 1/1613: {Profiling or modelling of patient or predicted treatment evolution or outcome}
- A61M 1/1615: {using measurements made at different flow rates}
- A61M 1/1647: {with flow rate measurement of the dialysis fluid, upstream and downstream of the dialyser}
- A61M 1/165: {with a dialyser bypass on the dialysis fluid line}
- A61M 1/34: Filtering material out of the blood by passing it through a membrane, i.e. hemofiltration or diafiltration
- A61M 1/3403: {Regulation parameters}
- A61M 1/341: {by measuring the filtrate rate or volume}
- A61M 1/3434: {with pre-dilution and post-dilution}
- A61M 1/3437: {downstream of the filter, e.g. post-dilution with filtrate}
- A61M 1/3441: {Substitution rate control as a function of the ultrafiltration rate}
- A61M 1/3444: {in which the collected ultra-filtrate expels an equal volume of substitution fluid from a reservoir}
- A61M 1/3448: {by mechanically linked pumps in both ultra-filtrate and substitution flow line}
- A61M 1/3607: {Regulation parameters}
- A61M 1/3609: {Physical characteristics of the blood, e.g. haematocrit, urea}
- A61M 1/3635: {Constructional details}
- A61M 2205/05: combined with other kinds of therapy
- A61M 2205/058: with ultrasound therapy
- A61M 2205/15: Detection of leaks
- A61M 2205/3331: Pressure; Flow
- A61M 2205/3334: Measuring or controlling the flow rate
- A61M 2205/3341: stabilising pressure or flow to avoid excessive variation
- A61M 2205/3351: Controlling upstream pump pressure
- A61M 2205/3355: Controlling downstream pump pressure
- A61M 2205/3365: Rotational speed
- A61M 2205/3368: Temperature
- A61M 2205/502: User interfaces, e.g. screens or keyboards
- A61M 2205/702: automatically during use
- A61M: DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY (introducing media into or onto the bodies of animals A61D7/00; means for inserting tampons A61F13/26; devices for administering food or medicines orally A61J; containers for collecting, storing or administering blood or medical fluids A61J1/05); DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY (surgery A61B; chemical aspects of surgical articles A61L); DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR {(Electrotherapy, e.g. producing anaesthesia by the use of alternating or intermittent currents A61N1/36021)}

## 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.

## Claims

### Claim 1

A medical treatment method, comprising:
at treatment times, flowing medicament into and out of inflow and outflow channels connectable to a patient or to a treatment device with at least a first peristaltic pump and a second peristaltic pump;
at calibration times, over a calibration interval of less than a minute, flowing the medicament through a bridge channel between the inflow and outflow channels such that pulsations generated by the first peristaltic pump and the second peristaltic pump generate pressure fluctuations in the bridge channel, wherein the pressure fluctuations are caused by a superposition of a suction side pulsation of the first peristaltic pump and a pressure side pulsation of the second peristaltic pump; and
adjusting flow resistance in a pumping tube of at least one of the first peristaltic pump and the second peristaltic pump using an adjustable flow restrictor to generate a suction head of at least one of the first peristaltic pump and the second peristaltic pump so as to change a pulsation frequency of the respective peristaltic pump so that the changed pulsation frequency differs from the pulsation frequency of the other peristaltic pump by a predetermined amount.

### Claim 2 (depends on 1)

The method of claim 1, wherein the predetermined amount is such that a ratio of an inverse of a difference between pulsation frequencies of the first peristaltic pump and the second peristaltic pump is multiple times the calibration interval.

### Claim 3 (depends on 1)

The method of claim 1, wherein the predetermined amount is such that a ratio of an inverse of a difference between pulsation frequencies of the first peristaltic pump and the second peristaltic pump is three times the calibration interval.

### Claim 4 (depends on 1)

The method of claim 1, wherein the predetermined amount is such that a ratio of an inverse of a difference between pulsation frequencies of the first peristaltic pump and the second peristaltic pump is five times the calibration interval.

### Claim 5 (depends on 1)

The method of claim 1, wherein the predetermined amount is such that a ratio of an inverse of a difference between pulsation frequencies of the first peristaltic pump and the second peristaltic pump is eight times the calibration interval.

### Claim 6 (depends on 1)

The method of claim 1, wherein the predetermined amount is such that a ratio of an inverse of a difference between pulsation frequencies of the first peristaltic pump and the second peristaltic pump is twelve times the calibration interval.

### Claim 7

A flow system, comprising:
a first peristaltic pump having rotors engaged with a first pumping tube segment and configured to pump fluid through the first pumping tube segment when the first peristaltic pump operates;
a second peristaltic pump having rotors engaged with a second pumping tube segment and configured to pump fluid through the second pumping tube segment when the second peristaltic pump operates;
a channel with a component fluidly connecting the first pumping tube segment to the second pumping tube segment and permitting a net flow into and out of the channel between the first and second peristaltic pumps, wherein
the first pumping tube segment has a different cross-sectional area than the second pumping tube segment,
when the first and second peristaltic pumps are pumping at equal flow rates, their rotational speeds are different,
the first peristaltic pump has a first pulsation frequency,
the second peristaltic pump has a second pulsation frequency,
superposition of the first pulsation frequency and the second pulsation frequency causes pressure fluctuations in the channel,
an adjustable flow restrictor is provided on at least one of the first pumping tube segment and the second pumping tube segment, and
the adjustable flow restrictor is adjusted to restrict flow and thereby cause the first pulsation frequency to differ from the second pulsation frequency by a predetermined amount.

### Claim 8 (depends on 7)

The system of claim 7, wherein the component includes a dialyzer.

### Claim 9 (depends on 7)

The system of claim 7, wherein the fluid is incompressible.

### Claim 10 (depends on 7)

The system of claim 7, wherein the first and second peristaltic pumps are interconnected by a fluid circuit that lacks a pulsation damper.