Method and device for detecting and assessing reactive hyperemia using segmental plethysmography

• US 10,226,186 B2
• Filed: 09/08/2017
• Issued: 03/12/2019
• Est. Priority Date: 06/02/2009
• Status: Active Grant

• Current Assignee: Cordex Systems, Inc.
• Original Assignee: Cordex Systems, Inc.
• Inventors: Whitt, Michael David, Magliato, Kathy Elizabeth, Ritterbush, Stephen, Shaw, Thomas Justin
• Primary Examiner(s): Weare, Meredith
• Application Number:
  US15/699,839
• Publication Number:
  US 20180042489A1
• Time in Patent Office: 550 Days
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/02255 the pressure being controlled by plethysmographic signals, e.g. derived from optical sensors
• CPC Class Codes: 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
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 5/7275 Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor
• CPC Class Codes: A61B 5/7282 Event detection, e.g. detecting unique waveforms indicative of a medical condition A61B5/4094, A61B5/4818, A61B5/349, A61B5/0823 take precedence
• CPC Class Codes: G16H 50/30 for calculating health indices; for individual health risk assessment
• CPC Class Codes: G16Z 99/00 Subject matter not provided for in other main groups of this subclass

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

1. A method for determining a risk of an endothelial dysfunction (ED)-related disease in a subject, comprising:

performing a first segmental cuff plethysmography having an inflation phase and a deflation phase and generating a first cuff compliance curve based only on data collected during the deflation phase of the first segmental cuff plethysmography;

generating a baseline arterial compliance curve and/or a baseline pressure-area (P-A) curve on a portion of the body of the subject, wherein the cuff pressure is increased to a first peak cuff pressure during the inflation phase and immediately reduced from the first peak cuff pressure during the deflation phase;

performing a second segmental cuff plethysmography having an inflation phase, a holding phase, and a deflation phase and generating a second cuff compliance curve based only on data collected during the deflation phase of the first segmental cuff plethysmography;

generating a hyperemic arterial compliance curve and/or a hyperemic P-A curve, wherein the cuff pressure is increased to a second peak level during the inflation phase, maintained at the second peak cuff pressure for a predetermined period of time during the holding phase, and then reduced from the second peak cuff pressure during the deflation phase;

calculating the difference between the baseline arterial compliance curve and the hyperemic arterial compliance curve as an area between the arterial compliance curves, and/or the difference between the baseline P-A curve and the hyperemic P-A curve as an area between the P-A curves;

measuring a level of reactive hyperemia based on the area between the arterial compliance curves and/or the area between the P-A curves; and

determining a risk of an ED-related disease based on the result of the measuring step, wherein the first and second cuff compliance curves are generated using a flowmeter that directly measures a volume change in the cuff during the deflation phase, and

wherein the ED-related disease is selected from the group consisting of coronary artery disease, heat stress, cirrhosis, hepatitis B and C, non-alcoholic steatohepatitis, fatty liver disease, all forms of dementia and psychological illness, and all illness related to localized or systemic inflammation and obesity.

2. The method of claim 1, wherein said cuff is inflated during the first and second segmental cuff plethysmography using a low-frequency pump.

3. The method of claim 2, wherein said low-frequency pump has an operation frequency of 10 Hertz or lower.

4. The method of claim 2, wherein said low-frequency pump has an operation frequency of 2 Hertz or lower.

5. The method of claim 1, further comprising:

determining a level of endothelial dysfunction (ED) in the subject based on the result of the measuring step.

6. The method of claim 1, wherein the first peak cuff pressure and the second peak cuff pressure are in the range of 150-180 mmHg.

7. The method of claim 1, wherein the predetermined period of time is about 2-10 minutes.

8. The method of claim 1, wherein the calculating step calculates the difference between the baseline arterial compliance curve and the hyperemic arterial compliance curve as an area between the arterial compliance curves within a transmural pressure range of 0-100 mmHg, and wherein the calculating step calculates the difference between the baseline P-A curve and the hyperemic P-A curve as an area between the P-A curves within a transmural pressure range of 0-100 mmHg.

9. The method of claim 8, wherein the calculating step calculates the difference between the baseline arterial compliance curve and the hyperemic arterial compliance curve as an area between the arterial compliance curves within a transmural pressure range of 20-80 mmHg, and wherein the calculating step calculates the difference between the baseline P-A curve and the hyperemic P-A curve as an area between the P-A curves within a transmural pressure range of 20-80 mmHg.

10. The method of claim 1, wherein the generation of said baseline arterial compliance curve and/or a baseline pressure-area (P-A) curve comprises applying a band pass filter of 0.5-5.0 Hertz to cuff pressure data collected during the deflation phase of said first segmental cuff plethysmography and wherein the generation of said hyperemia arterial compliance curve and/or hyperemia pressure-area (P-A) curve comprising applying a band pass filter of 0.5-5.0 Hertz to cuff pressure data collected during the deflation phase of said second segmental cuff plethysmography.

11. The method of claim 10, wherein an additional DC low pass filter between 0 Hz and 0.5 Hz is used to generate flowrate data during the deflation phase of said first and second segmental cuff plethysmography.

12. The method of claim 1, wherein the ED-related disease is coronary artery disease or heat stress.

13. The method of claim 1, wherein the ED-related disease is cirrhosis, hepatitis B, hepatitis C, non-alcoholic steatohepatitis or fatty liver disease.

14. The method of claim 1, wherein the ED-related disease is dementia.

15. The method of claim 1, wherein the ED-related disease is a psychological illness.

16. The method of claim 1, wherein the ED-related disease is an illness related to localized inflammation.

17. The method of claim 1, wherein the ED-related disease is an illness related to systemic inflammation.

18. The method of claim 1, wherein the ED-related disease is an illness related to obesity.