Method and device for detecting and assessing reactive hyperemia using segmental plethysmography
First Claim
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1. A method for measuring reactive hyperemia in a subject, comprising:
- performing a 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 and immediately reduced from the first peak cuff pressure;
performing a second 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, maintained at the second peak cuff pressure for a predetermined period of time, and then reduced from the second peak cuff pressure;
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; and
measuring a level of reactive hyperemia based on the area between the arterial compliance curves and/or the area between the P-A curves,wherein a first cuff compliance curve is generated during the first segmental cuff plethysmography and a second cuff compliance curve is generated during the second segmental cuff plethysmography, wherein said first and second cuff compliance curves are generated using a metering pump to measure the volume change in a cuff, and a pressure sensor to measure pressure change for each known volume change, and wherein the metering pump is a low-frequency pump operating at a frequency that is not higher than the arterial cycle frequency.
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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.
17 Citations
25 Claims
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1. A method for measuring reactive hyperemia in a subject, comprising:
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performing a 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 and immediately reduced from the first peak cuff pressure; performing a second 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, maintained at the second peak cuff pressure for a predetermined period of time, and then reduced from the second peak cuff pressure; 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; and measuring a level of reactive hyperemia based on the area between the arterial compliance curves and/or the area between the P-A curves, wherein a first cuff compliance curve is generated during the first segmental cuff plethysmography and a second cuff compliance curve is generated during the second segmental cuff plethysmography, wherein said first and second cuff compliance curves are generated using a metering pump to measure the volume change in a cuff, and a pressure sensor to measure pressure change for each known volume change, and wherein the metering pump is a low-frequency pump operating at a frequency that is not higher than the arterial cycle frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method for determining endothelial dysfunction (ED) in a subject, comprising:
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(a) inflating a cuff around a portion of the body of the subject and immediately deflating the cuff after reaching a first cuff pressure and measuring the volume and pressure changes in the cuff during the inflation process and the deflation process; (b) generating a first curve based on the measurements in step (a); (c) inflating the cuff around the portion of the body of the subject for the second time, maintaining the inflation at a second cuff pressure for a predetermined period of time, deflating the cuff, and measuring the volume and pressure changes in the cuff during the inflation process and the deflation process; (d) generating a second curve based on the measurements in step (c); (e) determining a difference between areas under the first curve and the second curve, wherein the first curve and the second curve are arterial compliance curves or pressure-area (P-A) curves; and (f) determining a level of endothelial dysfunction based on the difference determined in step (e), wherein a first cuff compliance curve is generated during step (a) and a second cuff compliance curve is generated during step (c) using a metering pump to directly measure the volume change in a cuff, and a pressure sensor to measure pressure change for each known volume change, and wherein the metering pump is a low-frequency pump operating at a frequency that is not higher than the arterial cycle frequency, wherein the first curve is generated based the first cuff compliance curve, and wherein the second curve is generated based the second cuff compliance curve. - View Dependent Claims (18, 19, 20, 21, 22)
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23. An apparatus comprising:
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an inflatable cuff; a metering pump for inflating and deflating the cuff; a pressure transducer for measuring the pressure inside the cuff; and a computer configured to; generate 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 and a P-A curve during the inflation and deflation process of the cuff; and calculate difference between areas under a first arterial compliance curve and a second arterial compliance curve and difference between areas under a first pressure-area (P-A) curve and a second P-A curve, wherein the metering pump is a low-frequency pump operating at a frequency that is not higher than the arterial cycle frequency. - View Dependent Claims (24, 25)
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Specification