Calibrated measurement of blood vessels and endothelium after reactive hyperemia and method therefor
First Claim
1. A calibrated method for characterizing blood flow in a limb of a patient during reactive hyperemia with a blood pressure cuff bound about said limb comprising the steps of:
- establishing a predetermined, near diastolic, pressure in said blood pressure cuff during the reactive hyperemic episode;
substantially continually sensing the pressure in said blood pressure cuff during the reactive hyperemic episode;
during the reactive hyperemic episode, periodically changing a volume of said blood pressure cuff by a predetermined volumetric amount and substantially concurrently sensing a resultant change in the pressure as a calibration pressure pulse;
calculating pulsatile blood volume by correcting the sensed pressure with the ratio of the predetermined volumetric amount and calibration pressure pulse.
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Abstract
The calibrated method for characterizing blood flow in a limb of a patient during reactive hyperemia utilizes a blood pressure cuff. The method establishes a predetermined, near diastolic, pressure in said blood pressure cuff during the reactive hyperemic episode, continually senses the pressure in the cuff and periodically changes the internal volume of said blood pressure cuff by a predetermined volumetric amount to calibrate the system. The resultant change in the pressure is a calibration pressure pulse and is used to calculates pulsatile blood volume through the blood vessel. A calibrated method for determining the condition of blood vessels and endothelium includes determining, for each calibration cycle, a respective peak value for the blood volume and comparing the peak blood volume values with peak blood volume values for healthy blood vessels and endothelium. The comparison preferably utilizes a waveform. The calibrated system for characterizing blood flow includes a computerized electronic and pneumatic system which inflates, for a predetermined pre-test time, the blood pressure cuff to a suprasystolic pressure and thereafter establishes the near diastolic pressure in the cuff during the ensuing reactive hyperemic episode. A sensor substantially continually senses the pressure and generates a pressure signal. A subsystem periodically changes the volume of said blood pressure cuff during a calibration cycle. A corrected and calibrated blood volume signal is calculated with the calibration pressure signal. A calibrated system for determining the condition of blood vessels and endothelium is also disclosed.
83 Citations
59 Claims
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1. A calibrated method for characterizing blood flow in a limb of a patient during reactive hyperemia with a blood pressure cuff bound about said limb comprising the steps of:
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establishing a predetermined, near diastolic, pressure in said blood pressure cuff during the reactive hyperemic episode; substantially continually sensing the pressure in said blood pressure cuff during the reactive hyperemic episode; during the reactive hyperemic episode, periodically changing a volume of said blood pressure cuff by a predetermined volumetric amount and substantially concurrently sensing a resultant change in the pressure as a calibration pressure pulse; calculating pulsatile blood volume by correcting the sensed pressure with the ratio of the predetermined volumetric amount and calibration pressure pulse. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A calibrated method for determining the condition of blood vessels and endothelium in a limb of a patient during reactive hyperemia with a blood pressure cuff bound about said limb comprising the steps of:
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establishing a predetermined, near diastolic, pressure in said blood pressure cuff during the reactive hyperemic episode; substantially continually sensing the pressure in said blood pressure cuff during substantially the entire reactive hyperemic episode; periodically changing a volume of said blood pressure cuff by a predetermined volumetric amount and substantially concurrently sensing a resultant change in the pressure as a calibration pressure pulse at a predetermined plurality of calibration cycles during said reactive hyperemic episode; determining, for each of said plurality of calibration cycles, a respective peak value for a blood volume, said blood volume obtained by correcting the sensed pressure, at each of said plurality of calibration cycles, with the ratio of the predetermined volumetric amount and calibration pressure pulse obtained during said respective calibration cycle; and comparing said peak values for said plurality of calibration cycles with a plurality of predetermined peak blood volume values for healthy blood vessels and endothelium during reactive hyperemia. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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37. A calibrated system for characterizing blood flow in a limb of a patient during reactive hyperemia with a blood pressure cuff bound about said limb comprising:
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means, coupled to said blood pressure cuff, for inflating, for a predetermined pre-test time, said blood pressure cuff to a suprasystolic pressure and thereafter establishing a predetermined, near diastolic, pressure in said blood pressure cuff during the ensuing reactive hyperemic episode; a sensor, pneumatically coupled to said blood pressure cuff, substantially continually sensing the pressure in said cuff and generating a pressure signal during the reactive hyperemic episode; means, coupled to said blood pressure cuff, for periodically changing a volume of said blood pressure cuff by a predetermined volumetric amount during the reactive hyperemic episode; means, coupled to said sensor, for generating a calibration pressure pulse signal based upon a resultant change in the pressure signal during the periodic change of volume; means for calculating a blood volume signal by correcting the sensed pressure signal with a ratio of the predetermined volumetric amount and said calibration pressure pulse signal; and means for quickly releasing said suprasystolic pressure in said blood pressure cuff prior to establishing said predetermined, near diastolic, pressure in said cuff.
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- 38. A calibrated system for characterizing blood flow during reactive hyperemia as claimed in 37 wherein said means for quickly releasing includes an exhaust valve.
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51. A calibrated system for determining the condition of blood vessels and endothelium in a limb of a patient during reactive hyperemia with a blood pressure cuff bound about said limb comprising:
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means, coupled to said blood pressure cuff, for inflating, for a predetermined pre-test time, said blood pressure cuff to a suprasystolic pressure and thereafter establishing a predetermined, near diastolic, pressure in said blood pressure cuff during the ensuing reactive hyperemic episode; a sensor, pneumatically coupled to said blood pressure cuff, substantially continually sensing the pressure in said cuff and generating a pressure signal during the reactive hyperemic episode, said pressure signal including a plurality of pressure pulse signals therein; means, coupled to said blood pressure cuff, for periodically changing a volume of said blood pressure cuff by a predetermined volumetric amount at a predetermined plurality of calibration cycles during the reactive hyperemic episode; means, coupled to said sensor and said means for periodically changing volume, for generating a calibration pressure pulse signal during each of said calibration cycles based upon a resultant change in the pressure signal; means, coupled to said sensor and said means for generating said calibration pulse signal, for determining, for each of said plurality of calibration cycles and during said reactive hyperemic episode, a respective peak value for a blood volume signal, said blood volume signal obtained by correcting the pressure pulse signal, at each of said plurality of calibration cycles, with the ratio of the predetermined volumetric amount and said calibration pressure pulse signal obtained during said respective calibration cycle; and means, coupled to said means for determining, for comparing the peak blood volume values for said plurality of calibration cycles with a plurality of predetermined peak blood volume values for healthy blood vessels and endothelium during reactive hyperemia. - View Dependent Claims (52, 53, 54, 55, 56, 57, 58, 59)
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Specification