# US 2010/0168641 A1 · Method and Apparatus for Blood Withdrawal and Infusion Using a Pressure Controller

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- Number: US 2010/0168641 A1
- Document ID: US20100168641A1
- Status: Published application
- Kind: A1
- Application number: 12/719,667
- Filed: 2010-03-08
- Published: 2010-07-01
- Earliest claimed: 2000-11-02
- Assignees: CHF Solutions, Inc.
- Inventors: John J. O'Mahony; Mark Gelfand; Edward G. Rychlick
- Web page: https://patentgrep.com/patent/US20100168641A1

## CPC

- A61M 1/34: Filtering material out of the blood by passing it through a membrane, i.e. hemofiltration or diafiltration
- A61M 1/341: {by measuring the filtrate rate or volume}
- A61M 1/3639: {Blood pressure control, pressure transducers specially adapted therefor}
- A61M 1/3656: {Monitoring patency or flow at connection sites; Detecting disconnections}
- B01D 61/22: Controlling or regulating
- A61M 1/1692: {Detection of blood traces in dialysate}
- A61M 2205/15: Detection of leaks
- A61M 2205/18: with alarm
- A61M 2205/3331: Pressure; Flow
- A61M 2205/3334: Measuring or controlling the flow rate
- A61M 2205/50: with microprocessors or computers
- A61M 2205/502: User interfaces, e.g. screens or keyboards
- 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)}
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)

## Abstract

A method and apparatus for controlling blood withdrawal and infusion flow rate with the use of a pressure controller. The pressure controller uses pressure targets based upon occlusion limits that are calculated as a function of flow. The controller has the ability to switch from controlling withdrawal pressure to controlling infusion pressure based upon the detection of an occlusion. The controller distinguishes between partial and total occlusions of the withdrawal vein providing blood access. Depending on the nature of occlusion, the controller limits or temporarily reverses blood flow and, thus, prevents withdrawal vessel collapse or reverses blood flow to quickly infuse blood into the vessel without participation from operator.

## Claims

### Claim 1

A method for controlling blood flow through an extracorporeal blood circuit comprising the steps of:
a. withdrawing the blood from a withdrawal blood vessel in a patient into the extracorporeal circuit;
b. detecting an occlusion which at least partially blocks the withdrawal of blood from the patient, and
c. temporarily reversing a flow of the blood to infuse blood from the circuit into the withdrawal blood vessel after step b.

### Claim 2 (depends on 1)

A method for controlling blood flow as in claim 1 wherein the occlusion is detected based on a pressure measurement of the blood in the circuit.

### Claim 3 (depends on 1)

A method for controlling blood flow as in claim 1 wherein step (a) is repeated after step (c).

### Claim 4 (depends on 1)

A method for controlling blood flow as in claim 1 wherein blood flow is reversed after the blood flow is substantially reduced during step (a).

### Claim 5 (depends on 1)

A method for controlling blood flow as in claim 1 wherein blood flow is reversed after the blood flow is substantially reduced to zero flow during step (a).

### Claim 6 (depends on 1)

A method for controlling blood flow as in claim 1 wherein blood flow is reversed after the withdrawal blood vessel collapses.

### Claim 7 (depends on 1)

A method for controlling blood flow as in claim 1 wherein the flow is temporarily reversed after an occlusion has been detected in the withdrawal blood vessel.

### Claim 8 (depends on 1)

A method for controlling blood flow as in claim 1 wherein the blood flow is reversed for a predetermined duration.

### Claim 9 (depends on 1)

A method for controlling blood flow as in claim 1 wherein the reversed blood flow has a predetermined flow rate.

### Claim 10 (depends on 9)

A method for controlling blood flow as in claim 9 wherein the flow rate is substantially less than the flow rate during step (a) and prior to step (b).

### Claim 11 (depends on 1)

A method for controlling blood flow as in claim 1 wherein the step (a) is repeated after step (c) when a flow capacity of the withdrawal blood vessel substantially increases.

### Claim 12 (depends on 1)

A method for controlling blood flow as in claim 1 further comprising a step of gradually reducing blood flow prior to step (b).

### Claim 13

A method of controlling an extracorporeal blood circuit comprising the steps of:
a. withdrawing blood from a withdrawal blood vessel in a patient into the extracorporeal circuit;
b. determining a withdrawal blood pressure in the extracorporeal circuit;
c. withdrawing blood at a flow rate selected to reduce a difference between the withdrawal pressure and an occlusion limit which is a function of blood flow through the circuit and withdrawal pressure, and
d. temporarily reversing blood flow to infuse blood from the circuit into the withdrawal blood vessel if the flow rate selected in step (b) is reduced to below a predetermined limit;

### Claim 14 (depends on 13)

A method of controlling an extracorporeal blood circuit as in claim 13 wherein the predetermined limit is a blood flow rate of substantially zero.

### Claim 15 (depends on 13)

A method of controlling an extracorporeal blood circuit as in claim 13 further comprising the steps of:
e. detecting an occlusion which at least partially blocks the withdrawal of blood from the patient, and
f. temporarily reversing a flow of the blood to infuse blood from the circuit into the withdrawal blood vessel if the step (b) of the algorithm is unsuccessful in maintaining significant blood flow.

### Claim 16

A method for controlling withdrawal of blood from a patient into an extracorporeal circuit, and allowing for detection of and recovery from a reduced flow capacity or total occlusion of a withdrawal blood vessel, comprising the steps of:
a. reducing blood flow being withdrawn from the patient when a withdrawal pressure of the blood in the circuit becomes more negative than an occlusion limit that is a function of blood flow through the circuit, and
b. if the reduced blood flow is reduced below a predetermined minimal flow during step (a), then temporarily reversing the flow of blood in the circuit and infusing blood into the withdrawal blood vessel.

### Claim 17 (depends on 16)

A method as in claim 16 further comprising the steps of:
c. prior to step (a), increasing a rate of blood being withdrawn until the withdrawal blood vessel begins to collapse and occlude blood withdrawal;
d. prior to step (a), determining an occlusion withdrawal pressure corresponding to collapse of the vessel,
e. initiating step (b) when the collapse withdrawal pressure is detected.

### Claim 18 (depends on 17)

A method as in the claim 17 wherein the collapse withdrawal pressure is a variable and a function of withdrawal blood flow.

### Claim 19 (depends on 17)

A method as in claim 17 wherein the collapse withdrawal pressure is periodically reestablished by stopping the blood flow through the circuit pump and then performing steps (c), (d) and (e).

### Claim 20

A system for controlling blood flow withdrawn from a patient comprising:
an extracorporeal circuit having a blood passage including a blood withdrawal tube, a treatment device and an infusion tube,
a pressure sensor coupled to said withdrawal tube and sensing a blood pressure in the withdrawal tube;
a pump coupled to the circuit and adapted to move blood through the blood passage at a controlled flow rate, and
a pump controller receiving a blood pressure signal from the pressure sensor and controlling the pump to regulate the controlled flow rate, wherein the pump controller includes a processor and a memory storing a control algorithm of a variable withdrawal pressure target as a function of flow rate, said controller reduces the controlled flow rate based on a difference between a withdrawal pressure sensed by the pressure sensor and the withdrawal pressure target, and said controller reverses blood flow to infuse blood into the patient through the withdrawal tube if the controlled flow rate is reduced below a predetermined limit.

### Claim 21 (depends on 20)

A system as in claim 20 wherein the pump controller includes a proportional integral feed forward pressure controller.

### Claim 22 (depends on 20)

A system as in claim 20 wherein the treatment device is a hemofilter.

### Claim 23 (depends on 20)

A system as in claim 20 wherein the treatment device is a dialysis device.

### Claim 24 (depends on 20)

A system as in claim 20 wherein the pressure sensor is a real time sensor providing real time pressure signals to the pump controller.

### Claim 25 (depends on 20)

A system as in claim 20 wherein the pump includes a direct DC drive motor.

### Claim 26 (depends on 25)

A system as in claim 25 wherein the drive motor is a brushless motor.

### Claim 27 (depends on 20)

A system as in claim 20 wherein the treatment device is a blood filter.

### Claim 28 (depends on 20)

A system as in claim 20 wherein the pressure controller alternatively controls a withdrawal pressure and an infusion pressure by synchronized switching.

### Claim 29

A method for controlling blood flow in a closed loop extracorporeal blood circulation system where blood is withdrawn and returned into a blood vessel in the same body in the process of treatment comprising the steps of:
a. withdrawing blood from a blood vessel of the patient at a controlled flow rate;
b. measuring a withdrawal pressure of the withdrawn blood;
c. infusing the withdrawn blood into the patient;
e. measuring the infusion pressure of the blood;
f. comparing the withdrawal pressure to a withdrawal pressure target, and comparing the infusion pressure to an infusion pressure target;
g. adjusting the flow rate to reduce a difference between the withdrawal pressure and a withdrawal pressure target, if the infusion pressure is less than an infusion pressure target, and
h. adjusting the flow rate to reduce a difference between the infusion pressure and an infusion pressure target, if the infusion pressure is greater than the infusion pressure target.

### Claim 30 (depends on 29)

A method as in claim 29 wherein step (h) includes applying a difference between the infusion pressure and the infusion pressure target as feedback to adjust the flow rate of the blood being withdrawn.

### Claim 31 (depends on 29)

A method as in claim 29 wherein the blood is withdrawn through a withdrawal needle and infused through an infusion needle.

### Claim 32 (depends on 31)

A method as in claim 31 wherein the blood is withdrawn through a needle and infused through said needle.

### Claim 33

A method as in 29 wherein blood is withdrawn from and infused into a peripheral vein of a patient.

### Claim 34

A method for limiting pump pressure in an extracorporeal blood circuit coupled to a pump driven by a direct DC drive motor, wherein the method comprises the steps of:
a. measuring current used by the motor,
b. limiting pressure in said blood circuit by controlling said current, and
c. controlling the current based on a difference between a measured blood pressure in the circuit and a pressure target.

### Claim 35

A method for controlling blood infusion into a mammalian patient in an air-free extracorporeal blood circuit comprising the steps of:
a. infusing blood from the circuit into a blood vessel of the patient at a controlled infusion flow rate;
b. measuring an infusion pressure of the blood being infused;
c. comparing the measured infusion pressure to a disconnect pressure target;
d. sensing for air in the blood being infused;
e. generating a disconnection alarm if both the measured infusion pressure is no greater than the disconnect pressure target and air is sensed in the blood being infused.

### Claim 36 (depends on 35)

A method for controlling blood infusion as in claim 35, further comprising the step of reducing a rate of infusing blood if the measured infusion pressure is greater than the disconnect pressure target and air is not sensed in the blood being infused.