# US 12,004,848 B2 · Blood flow meter

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- Number: US 12,004,848 B2
- Document ID: US12004848B2
- Status: Granted
- Kind: B2
- Application number: 16/672,562
- Filed: 2019-11-04
- Published: 2020-05-07
- Granted: 2024-06-11
- Earliest claimed: 2018-11-02
- Assignees: Boston Scientific Medical Device Limited
- Applicants: Boston Scientific Limited
- Inventors: Deepak Kumar Sharma
- Web page: https://patentgrep.com/patent/US12004848B2

## CPC

- A61B 5/027: using catheters
- A61B 5/02158: {provided with two or more sensor elements}
- A61B 5/6852: {Catheters}
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

A blood flow meter includes a rotor configured to be placed within a flow of blood and to be driven to rotate by the flow of blood; a magnetic encoder configured to sense the rotation of the rotor and to generate a rotation signal based on the sensed rotation of the rotor; a first pressure sensor configured to measure an upstream pressure; a second pressure sensor configured to measure a downstream pressure; and a control unit. The control unit is configured to determine a differential pressure, the differential pressure including a difference between the downstream pressure and the upstream pressure; and cause an alteration to the rotation of the rotor based on the differential pressure.

## Claims

### Claim 1

A method of using a blood flow meter having a rotor placed in the flow of blood to determine a blood flow rate, the method comprising:
initially permitting the rotor to rotate due to flow of blood over a plurality of blades of the rotor; and thereafter
measuring, using an upstream pressure sensor, an upstream pressure, wherein the upstream pressure is the blood pressure upstream of the rotor;
measuring, using a downstream pressure sensor, a downstream pressure, wherein the downstream pressure is the blood pressure downstream of the rotor;
determining that a differential pressure is not zero, the differential pressure comprising a difference between the downstream pressure and the upstream pressure;
causing an alteration to the rotation of the rotor in response to determining that the differential pressure is not zero;
sensing, using a magnetic encoder, the rotation of the rotor;
generating, using the magnetic encoder and based on the rotation of the rotor, a rotation signal; and
determining, based on the rotation signal, the blood flow rate.

### Claim 2 (depends on 1)

The method of claim 1, wherein the step of determining the differential pressure is performed using a differential transducer.

### Claim 3 (depends on 1)

The method of claim 1, the blood flow meter comprising a motor configured to provide external energy to the rotor, thereby causing the alteration to the rotation of the rotor.

### Claim 4 (depends on 3)

The method of claim 3, wherein the motor is a stepper motor.

### Claim 5 (depends on 3)

The method of claim 3, the blood flow meter comprising a controller, the method further comprising providing, using the controller, a control signal to the motor to control the motor.

### Claim 6 (depends on 5)

The method of claim 5, wherein determining the blood flow rate based on the rotation signal comprises using the controller to determine the blood flow rate.

### Claim 7 (depends on 5)

The method of claim 5, wherein the controller is operatively coupled to the upstream pressure sensor and the downstream pressure sensor.

### Claim 8 (depends on 1)

The method of claim 1, further comprising inserting the blood flow meter into a blood vessel before permitting the rotor to rotate due to the flow of blood over the plurality of blades of the rotor.

### Claim 9 (depends on 1)

The method of claim 1, wherein causing the alteration to the rotation of the rotor in response to determining that the differential pressure is not zero comprises maintaining a zero slip condition based on the differential pressure.