# US 11,298,446 B2 · Systems and methods for calibrating pump stroke volumes during a blood separation procedure

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- Number: US 11,298,446 B2
- Document ID: US11298446B2
- Status: Granted
- Kind: B2
- Application number: 14/577,236
- Filed: 2014-12-19
- Published: 2016-06-23
- Granted: 2022-04-12
- Earliest claimed: 2014-12-19
- Assignees: Fenwal, Inc.
- Applicants: Fenwal, Inc.
- Inventors: Samantha M. Planas; Amit J. Patel; Kathleen M. Higginson
- Web page: https://patentgrep.com/patent/US11298446B2

## CPC

- A61M 1/267: {used for pumping}
- A61M 1/0209: {Multiple bag systems for separating or storing blood components}
- 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 1/265: {inducing Taylor vortices}
- A61M 1/3496: {Plasmapheresis; Leucopheresis; Lymphopheresis (A61M1/3472 takes precedence)}
- A61M 60/104: Extracorporeal pumps, i.e. the blood being pumped outside the patient's body
- A61M 60/279: Peristaltic pumps, e.g. roller pumps
- A61M 60/39: for blood transfusion
- A61M 60/457: the force acting on the blood contacting member being magnetic
- A61M 60/546: of blood flow, e.g. by adapting rotor speed
- A61M 60/837: Aspects of flexible displacement members, e.g. shapes or materials
- A61M 60/851: Valves
- A61M 60/113: in other functional devices, e.g. dialysers or heart-lung machines
- A61M 2205/3334: Measuring or controlling the flow rate
- 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

A method is provided for calibrating a pump during a blood separation procedure that has at least a first and second state or phase where fluid is flowed to or from a reservoir by action of the pump. The state or phase of the procedure may be a priming state, a draw state, a separation state and a return state, and the pump calibration may be performed between consecutive performances of the same procedure state. The calibration is based on a variance between the volume of fluid predicted to be processed by the pump for the given state of the procedure and the actual volume processed based on the change of weight of the reservoir. Recalibration of the pump, if necessary, is accomplished before the performance of the second phase is commenced.

## Claims

### Claim 1

A method for adjusting a pump flow rate during a blood separation procedure having an initial performance of a first state and a second performance of the first state where fluid is flowed to or from a reservoir by the pump, the pump flow rate being adjusted between the initial and second performances of the first state, the method comprising:
a) establishing a minimum volume of fluid to be pumped during the initial performance of the first state of the procedure in an amount to account for permissible tolerances;
b) providing a predetermined value for a flow rate of fluid to or from the reservoir for the initial performance of the first state of the procedure;
c) weighing the reservoir at the beginning of the initial performance of the first state of the procedure;
d) operating the pump to flow fluid to or from the reservoir to perform the initial performance of the first state of the procedure;
e) weighing the reservoir at the end of the initial performance of the first state of the procedure;
comparing the weight of the reservoir at the beginning of the initial performance of the first state of the procedure to the weight of the reservoir at the end of the initial performance of the first state of the procedure to determine an actual volume of fluid pumped during the initial performance of the first state of the procedure and to determine an actual flow rate of fluid to or from the reservoir;
g) comparing the minimum volume of fluid to be pumped during the initial performance of the first state of the procedure to the actual volume of fluid pumped during the first state of the procedure;
h) if the actual volume of fluid pumped during the initial performance of the first state of the procedure exceeds the minimum volume of fluid to be pumped, then determining a variance between the actual flow rate and the predetermined value for the flow rate;
i) calculating a pump volume for the initial performance of the first state of the procedure;
j) adjusting the predetermined value for the flow rate for the second performance of the first state of the procedure based on the variance, wherein a maximum permissible adjustment of the predetermined value for the flow rate from the initial performance of the first state to the second performance of the first state is limited to a predetermined amount that is less than the variance between the predetermined value for the flow rate and the actual flow rate; and
k) operating the pump at the predetermined value for the flow rate for the second performance of the first state of the procedure to flow fluid to or from the reservoir to perform the second performance of the first state of the procedure.

### Claim 2 (depends on 1)

The method of claim 1 wherein the predetermined value for the flow rate for the initial performance of the first state of the procedure is obtained based on a nominal pump stroke volume and an anticipated number of pump strokes to be performed by the pump.

### Claim 3 (depends on 1)

The method of claim 1 wherein the first predetermined amount is the calculated pump volume for the first state of the procedure is from 10 mL to 1000 mL.

### Claim 4 (depends on 1)

The method of claim 1 wherein the second predetermined amount is from 1% to 50%.

### Claim 5 (depends on 1)

The method of claim 1 wherein the second predetermined amount is from 1 mL/min to 50 mL/min.

### Claim 6 (depends on 1)

The method of claim 1 wherein the pump is a blood pump and the first state of the procedure is a draw state.

### Claim 7 (depends on 1)

The method of claim 1 wherein the pump is a blood pump and the first state of the procedure is a return state.

### Claim 8 (depends on 1)

The method of claim 1 wherein the pump is a cell pump and the first state is a separation state.

### Claim 9 (depends on 1)

The method of claim 1 wherein the pump is an AC pump and the first state of the procedure is a prime state.

### Claim 10 (depends on 1)

The method of claim 1 wherein the pump is an AC pump and the first state of the procedure is a draw state.

### Claim 11 (depends on 1)

The method of claim 1 in which the pump is a cell pump and the fluid in the reservoir is a return fluid that has a target hematocrit, the method further comprising reducing the target hematocrit of the fluid in the reservoir if the pump recalibration adjustment results in a slower pump speed.

### Claim 12 (depends on 1)

The method of claim 1 in which the pump is a blood pump and the fluid in the reservoir is a return fluid that has a target hematocrit, the method further comprising reducing the target hematocrit of the fluid in the reservoir if the pump recalibration adjustment results in an increased pump speed.

### Claim 13

In a blood separation procedure comprising one or more of a priming state, a draw state, a separation state and a return state and utilizing a system comprising a fluid circuit with at least one reservoir and a pump for flowing fluid through the fluid circuit during each state, a method for adjusting a pump flow rate for consecutive performances of the same procedure state, comprising:
a) establishing a minimum volume of fluid to be pumped during the initial performance of a selected first state of the procedure in an amount to account for permissible tolerances;
b) providing a predetermined value for a flow rate of fluid to or from the reservoir for the selected first state of the procedure;
c) weighing the reservoir at the beginning of the initial performance of the selected first state of the procedure;
d) operating the pump to flow fluid to or from the reservoir for the initial performance of the selected first state of the procedure;
e) weighing the reservoir at the end of the initial performance of the selected first state of the procedure;
f) comparing the weight of the reservoir at the beginning of the initial performance of the selected first state of the procedure to the weight of the reservoir at the end of the initial performance of the selected first state of the procedure to determine an actual volume of fluid pumped during the initial performance of the selected first state of the procedure and to determine an actual flow rate of fluid to or from the reservoir;
g) comparing the minimum volume of fluid to be pumped during the initial performance of the selected first state of the procedure to the actual volume of fluid pumped during the initial performance of the selected first state of the procedure;
h) if the actual volume of fluid pumped during the initial performance of the selected first state of the procedure exceeds the minimum volume of fluid to be pumped, then determining a variance between the actual flow rate and the predetermined value for the flow rate;
i) calculating a pump volume for the initial performance of the selected first state of the procedure;
j) adjusting the predetermined value for the flow rate for a subsequent performance of the selected first state of the procedure based on the variance wherein a maximum permissible adjustment of the predetermined value for the flow rate from the initial performance of the selected first state to the subsequent performance of the selected first state is limited to a predetermined amount that is less than the variance between the predetermined value for the flow rate and the actual flow rate; and
k) operating the pump at the predetermined value for the flow rate for the subsequent performance of the selected first state of the procedure to flow fluid to or from the reservoir for the subsequent performance of the same state of the procedure.

### Claim 14 (depends on 13)

The method of claim 13 wherein the predetermined value for the flow rate for the initial performance of the selected first state of the procedure is obtained based on a nominal pump stroke volume and an anticipated number of pump strokes to be performed by the pump.

### Claim 15 (depends on 13)

The method of claim 13 wherein the predetermined amount is from 10 mL to 1000 mL.

### Claim 16 (depends on 13)

The method of claim 13 wherein the second predetermined amount is from 1% to 50%.

### Claim 17 (depends on 13)

The method of claim 13 wherein the second predetermined amount is from 1 mL/min to 50 mL/min.

### Claim 18 (depends on 13)

The method of claim 13 wherein the pump is a blood pump and the selected first state of the procedure is a draw state.

### Claim 19 (depends on 13)

The method of claim 13 wherein the pump is a blood pump and the selected first state of the procedure is a return state.

### Claim 20 (depends on 13)

The method of claim 13 wherein the pump is a cell pump and the selected first state of the procedure is a separation state.

### Claim 21 (depends on 13)

The method of claim 13 in which the pump is a cell pump and the fluid in the reservoir is a return fluid that has a target hematocrit, the method further comprising reducing the target hematocrit of the fluid in the reservoir if the pump recalibration adjustment results in a slower pump speed.

### Claim 22 (depends on 13)

The method of claim 13 in which the pump is a blood pump and the fluid in the reservoir is a return fluid that has a target hematocrit, the method further comprising reducing the target hematocrit of the fluid in the reservoir if the pump recalibration adjustment results in an increased pump speed.