Assessing endothelial function and providing calibrated UFMD data using a blood pressure cuff
First Claim
1. An apparatus for assessment of endothelial function in a mammal comprising:
- a measurement cuff adapted to apply pressure to an artery in said mammal;
a measurement unit adapted to detect and quantify, over one or more cardiac cycles, pressure pulses in said cuff while said pressure is applied;
a controller that is adapted to apply to the cuff different pressures within a single time period (Tm), or to apply substantially constant pressures that differ in different time periods (Tm(s)) where;
said controller monitors cuff pressure and adjusts a pneumatic regulator to maintain substantially constant pressure in said cuff and where the response time of said cuff and controller is sufficiently slow so that the changes in pressure resulting from said one or more cardiac cycles are not substantially attenuated;
orsaid controller monitors cuff pressure and adjusts a valve operably coupled to a pressure source to provide on-off control of the pressure in said cuff where the pressure can change over time; and
a processor adapted to determine a plurality of baseline values for a parameter related to endothelial function as a function of applied pressure (Pm) and to determine a plurality of stimulus-effected values for a parameter related to endothelial function as a function of applied pressure (Pm), wherein said processor is adapted todetermine a measure proportional to the area of the arterial lumen calculated from the baseline pressure measurements as a function of transmural pressure Ptm, where transmural pressure is determined as the difference between the baseline measured pressures and the applied pressure Pm and fitting these data with a first non-linear model to provide a first function describing baseline arterial lumen area as function of transmural pressure;
to determine a measure proportional to the area of the arterial lumen calculated from the stimulus-effected pressure measurements as a function of transmural pressure Ptm, where transmural pressure is determined as the difference between the measured stimulus-effected pressures and the applied pressure Pm and fitting these data with a second non-linear model to provide a second function describing stimulus-effected arterial lumen area as function of transmural pressure;
to use said first function to calculate a measure proportional to baseline arterial lumen area (Ab) at a transmural pressure substantially equal to the systolic blood pressure; and
to use said second function to calculate a measure proportional to stimulus-effected arterial lumen area (Ar) at a transmural pressure substantially equal to the systolic blood pressure; and
to determine the equivalent ultrasound-based flow-mediated vasodilation (uFMD) where uFMD is proportional to the square root of the ratio Ar/Ab.
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Accused Products
Abstract
Methods and apparatus are provided for assessing endothelial function in a mammal. In certain embodiments the methods involve using a cuff to apply pressure to an artery in a subject to determine a plurality of baseline values for a parameter related to endothelial function as a function of applied pressure (Pm); b) applying a stimulus to the subject; and applying external pressure Pm to the artery to determine a plurality of stimulus-effected values for the parameter related to endothelial function as a function of applied pressure (Pm); where the baseline values are determined from measurements made when said mammal is not substantially effected by said stimulus and differences in said baseline values and said stimulus-effected values provide a measure of endothelial function in said mammal.
88 Citations
18 Claims
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1. An apparatus for assessment of endothelial function in a mammal comprising:
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a measurement cuff adapted to apply pressure to an artery in said mammal; a measurement unit adapted to detect and quantify, over one or more cardiac cycles, pressure pulses in said cuff while said pressure is applied; a controller that is adapted to apply to the cuff different pressures within a single time period (Tm), or to apply substantially constant pressures that differ in different time periods (Tm(s)) where; said controller monitors cuff pressure and adjusts a pneumatic regulator to maintain substantially constant pressure in said cuff and where the response time of said cuff and controller is sufficiently slow so that the changes in pressure resulting from said one or more cardiac cycles are not substantially attenuated;
orsaid controller monitors cuff pressure and adjusts a valve operably coupled to a pressure source to provide on-off control of the pressure in said cuff where the pressure can change over time; and a processor adapted to determine a plurality of baseline values for a parameter related to endothelial function as a function of applied pressure (Pm) and to determine a plurality of stimulus-effected values for a parameter related to endothelial function as a function of applied pressure (Pm), wherein said processor is adapted to determine a measure proportional to the area of the arterial lumen calculated from the baseline pressure measurements as a function of transmural pressure Ptm, where transmural pressure is determined as the difference between the baseline measured pressures and the applied pressure Pm and fitting these data with a first non-linear model to provide a first function describing baseline arterial lumen area as function of transmural pressure; to determine a measure proportional to the area of the arterial lumen calculated from the stimulus-effected pressure measurements as a function of transmural pressure Ptm, where transmural pressure is determined as the difference between the measured stimulus-effected pressures and the applied pressure Pm and fitting these data with a second non-linear model to provide a second function describing stimulus-effected arterial lumen area as function of transmural pressure; to use said first function to calculate a measure proportional to baseline arterial lumen area (Ab) at a transmural pressure substantially equal to the systolic blood pressure; and to use said second function to calculate a measure proportional to stimulus-effected arterial lumen area (Ar) at a transmural pressure substantially equal to the systolic blood pressure; and to determine the equivalent ultrasound-based flow-mediated vasodilation (uFMD) where uFMD is proportional to the square root of the ratio Ar/Ab. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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Specification