# US 2014/0194754 A1 · Method and device for detecting and assessing reactive hyperemia using segmental plethysmography

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- Number: US 2014/0194754 A1
- Document ID: US20140194754A1
- Status: Published application
- Kind: A1
- Application number: 14/204,678
- Filed: 2014-03-11
- Published: 2014-07-10
- Earliest claimed: 2009-06-02
- Assignees: Cordex Systems, Inc.
- Applicants: Cordex Systems, LLC
- Inventors: Michael David WHITT; Kathy Elizabeth MAGLIATO; Stephen RITTERBUSH
- Web page: https://patentgrep.com/patent/US20140194754A1

## CPC

- A61B 5/0295: using plethysmography, i.e. measuring the variations in the volume of a body part as modified by the circulation of blood therethrough, e.g. impedance plethysmography
- A61B 5/02007: {Evaluating blood vessel condition, e.g. elasticity, compliance}
- A61B 5/022: by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
- A61B 5/02255: {the pressure being controlled by plethysmographic signals, e.g. derived from optical sensors}
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

A method for measuring reactive hyperemia in a subject is disclosed. The method includes performing a first segmental cuff plethysmography to generate a baseline arterial compliance curve and/or a baseline pressure-area (P-A) curve, performing a second segmental cuff plethysmography to generate a hyperemic arterial compliance curve and/or a hyperemic P-A curve, and calculating an area between the baseline and the hyperemic curves. The size of the area can be used as an indication of endothelial dysfunction (ED) and ED-related diseases.

## Claims

### Claim at position 1

1-25. (canceled)

### Claim 26

A method for measuring arterial blood flow in a subject, comprising:
performing a first segmental cuff plethysmography on a portion of the body of the subject with an inflatable cuff having a cuff pressure, wherein the cuff pressure is increased to a peak cuff pressure and immediately reduced from the peak cuff pressure;
generating a pressure descent curve and a cuff compliance (dV/dP)cuff curve based on change in cuff pressure and cuff volume;
generating an arterial compliance (dV/dP)artery curve;
obtaining values of (dV/dP)artery at any transmural pressure based on said arterial compliance (dV/dP)artery curve;
taking derivative of said pressure descent curve to obtain a (dP/dt)artery curve;
multiplying (dP/dt)artery by (dV/dP)artery to obtain an arterial flow curve (dV/dt)artery.

### Claim 27 (depends on 26)

The method of claim 26, wherein said cuff compliance curve is generated using a metering pump to measure the volume change in the cuff and a pressure sensor to measure pressure change for each known volume change.

### Claim 28 (depends on 27)

The method of claim 27, wherein said metering pump is a low-frequency pump operating at a frequency that is not higher than the arterial cycle frequency.

### Claim 29 (depends on 26)

The method of claim 26, wherein the peak cuff pressure is in the range of 150-180 mmHg.

### Claim 30 (depends on 26)

The method of claim 26, wherein the arterial compliance (dV/dP)artery is obtained via the following equation:
(

V

P
)
artery
=
(

P
)
artery
×
(

V

P
)
cuff
[
P
sys
-
P
dia
]
wherein (dP)artery is the magnitude of pressure pulses that take place at each cuff pressure, Psys is systolic blood pressure, and Pdia is diastolic blood pressure.

### Claim 31 (depends on 30)

The method of claim 30, wherein a band pass filtering method is used on cuff compliance (dV/dP)cuff curve to obtain Psys and Pdia.

### Claim 32

An apparatus for measuring arterial blood flow in a subject, comprising:
an inflatable cuff;
a metering pump for inflating the cuff;
a pressure transducer for measuring the pressure inside the cuff; and
a computer configured to:
generate a pressure descent curve and a cuff compliance curve by directly measuring volume change in said cuff with said metering pump and pressure change inside the cuff with said pressure transducer;
calculate an arterial compliance curve during the inflation and deflation process of the cuff; and
generate an arterial compliance (dV/dP)artery curve;
obtain values of (dV/dP)artery at any transmural pressure based on the arterial compliance (dV/dP)artery curve;
take derivative of said pressure descent curve to obtain a (dP/dt)artery curve;
multiply (dP/dt)artery by (dV/dP)artery to obtain an arterial flow (dV/dt)artery curve.

### Claim 33 (depends on 32)

The apparatus of claim 32, wherein the metering pump is a low-frequency pump operating at a frequency that is not higher than the arterial cycle frequency.

### Claim 34 (depends on 33)

The apparatus of claim 33, further comprising an amplifier.

### Claim 35 (depends on 34)

The apparatus of claim 34, further comprising means for band pass filtering data.