System and method of measuring changes in arterial volume of a limb segment
First Claim
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1. A method for assessing change in arterial volume of a limb segment of a mammal, said method comprising:
- determining amplitudes of component pulse waves of detected volume pulse waves of a limb segment detected during a baseline period to determine a baseline arterial volume of the limb segment;
applying a stimulus to the mammal to induce a period of change in the arterial volume of the limb segment;
determining amplitudes of component pulse waves of detected volume pulse waves of the limb segment detected during a time period after the stimulus has been applied to the mammal to induce a period of change in the arterial volume of the limb segment; and
determining relative change in arterial volume of the limb segment during the time period after the stimulus relative to the arterial volume of the limb segment during the baseline period from the amplitudes of the component pulse waves of the detected volume pulse waves during the baseline and after the stimulus;
wherein determining relative change in arterial volume of the limb comprises;
calculating an average component pulse wave amplitude during the baseline period;
generating a curve fit of component pulse wave amplitudes during the after-stimulus period;
calculating a maximum of the fitted curve;
determining a time between beginning of the after-stimulus period and the time of the maximum of the fitted curve;
determining a relative amplitude change from the baseline to the maximum of the fitted curve; and
determining a relative change in arterial volume from the relative amplitude change from the baseline to the maximum of the fitted curve and the average component pulse wave amplitude during the baseline period.
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Abstract
A medical diagnostic device performs diagnostics for assessing the ability of the arteries to respond to an increase in blood flow. The medical diagnostic device determines relative changes in arterial volume of the limb segment during a time period after a stimulus relative to the arterial volume of the limb segment during a baseline period using the amplitudes or other portions of the component pulse waves (such as early systolic components) of volume pulse waves during the baseline period and after the stimulus.
209 Citations
49 Claims
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1. A method for assessing change in arterial volume of a limb segment of a mammal, said method comprising:
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determining amplitudes of component pulse waves of detected volume pulse waves of a limb segment detected during a baseline period to determine a baseline arterial volume of the limb segment; applying a stimulus to the mammal to induce a period of change in the arterial volume of the limb segment; determining amplitudes of component pulse waves of detected volume pulse waves of the limb segment detected during a time period after the stimulus has been applied to the mammal to induce a period of change in the arterial volume of the limb segment; and determining relative change in arterial volume of the limb segment during the time period after the stimulus relative to the arterial volume of the limb segment during the baseline period from the amplitudes of the component pulse waves of the detected volume pulse waves during the baseline and after the stimulus; wherein determining relative change in arterial volume of the limb comprises; calculating an average component pulse wave amplitude during the baseline period; generating a curve fit of component pulse wave amplitudes during the after-stimulus period; calculating a maximum of the fitted curve; determining a time between beginning of the after-stimulus period and the time of the maximum of the fitted curve; determining a relative amplitude change from the baseline to the maximum of the fitted curve; and determining a relative change in arterial volume from the relative amplitude change from the baseline to the maximum of the fitted curve and the average component pulse wave amplitude during the baseline period. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for assessing change in arterial volume of a limb segment of a mammal, said method comprising:
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monitoring a limb segment to record detected volume pulse waves of the limb segment during a baseline period; determining amplitudes of component pulse waves of the detected volume pulse waves of the limb segment detected during the baseline period to determine a baseline arterial volume of the limb segment; applying a stimulus to the mammal to induce a period of change in the arterial volume of the limb segment; monitoring the limb segment to record detected volume pulse waves of the limb segment during an after-stimulus period after the stimulus has been applied; determining amplitudes of component pulse waves of detected volume pulse waves of the limb segment detected during the after-stimulus period; and determining relative change in arterial volume of the limb segment during the after-stimulus period relative to the arterial volume of the limb segment during the baseline period from the amplitudes of the component pulse waves of the detected volume pulse waves during the baseline and after-stimulus periods; wherein monitoring the limb segment during the baseline and after-stimulus periods each comprise; applying, in a series, an external pressure to the limb segment at a mean arterial pressure of the limb; and detecting volume pulse waves of the limb segment.
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14. A method for assessing change in arterial volume of a limb segment of a mammal, said method comprising:
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monitoring a limb segment to record detected volume pulse waves of the limb segment during a baseline period; determining amplitudes of component pulse waves of the detected volume pulse waves of the limb segment detected during the baseline period to determine a baseline arterial volume of the limb segment; applying a stimulus to the mammal to induce a period of change in the arterial volume of the limb segment; monitoring the limb segment to record detected volume pulse waves of the limb segment during an after-stimulus period after the stimulus has been applied; determining amplitudes of component pulse waves of detected volume pulse waves of the limb segment detected during the after-stimulus period; and determining relative change in arterial volume of the limb segment during the after-stimulus period relative to the arterial volume of the limb segment during the baseline period from the amplitudes of the component pulse waves of the detected volume pulse waves during the baseline and after-stimulus periods; wherein monitoring the limb segment during the baseline and after-stimulus periods each comprise; applying an external pressure to the limb segment at a pressure level which allows blood flow through the artery to produce said volume pulse waves in response to the applied external pressure. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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21. A method for assessing change in arterial volume of a limb segment of a mammal, said method comprising:
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determining amplitudes of component pulse waves of detected volume pulse waves of a limb segment detected during a baseline period to determine a baseline arterial volume of the limb segment; applying a stimulus to the mammal to induce a period of change in the arterial volume of the limb segment; determining amplitudes of component pulse waves of detected volume pulse waves of the limb segment detected during a time period after a stimulus has been and determining relative change in arterial volume of the limb segment during the time period after the stimulus relative to the arterial volume of the limb segment during the baseline period from the amplitudes of the component pulse waves of the detected volume pulse waves during the baseline and after the stimulus; wherein the component pulse wave is an early systolic component; and wherein determining amplitude of early systolic component of a volume pulse wave comprises; computing a fourth derivative of the detected volume pulse wave; determining a time at which the fourth derivative reaches a third zero crossing; determining a pressure value on the detected volume pulse wave at said time; determining a pressure value at the beginning of the volume pulse wave; and assessing the amplitude of the early systolic component of the volume pulse wave as the difference between said pressures values. - View Dependent Claims (22)
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23. A diagnostic system for assessing change in arterial volume of a limb segment of a mammal comprising:
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a sensor for detecting volume pulse waves of a limb segment during a baseline period and for detecting volume pulse waves of the limb segment during a period of an after-stimulus change in arterial volume; a processor coupled to the sensor to determine amplitudes of component pulse waves of detected volume pulse waves of the limb segment detected during the baseline period to determine a baseline arterial volume of the limb segment, to determine amplitudes of component pulse waves of detected volume pulse waves of the limb segment detected during a time period after a stimulus has been applied to the mammal to induce a period of change in the arterial volume of the limb segment, and to determine relative change in arterial volume of the limb segment during the time period after the stimulus relative to the arterial volume of the limb during the baseline period from the amplitudes of the component pulse waves of the detected volume pulse waves at baseline and after the stimulus; wherein the processor calculates an average pulse wave amplitude during the baseline period, generates a curve fit of pulse wave amplitudes during the after-stimulus period, calculates a maximum of the fitted curve, determines a time between beginning of the after-stimulus period and the time of the maximum of the fitted curve, determines a relative amplitude change from the baseline to the maximum of the fitted curve, and determines a relative change in arterial volume from the relative amplitude change from the baseline to the maximum of the fitted curve and the average pulse wave amplitude during the baseline period to determine relative change in arterial volume of the limb. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. A diagnostic system for assessing change in arterial volume of a limb segment of a mammal comprising:
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a sensor for detecting volume pulse waves of a limb segment during a baseline period and for detecting volume pulse waves of the limb segment during a period of an after-stimulus change in arterial volume; a processor coupled to the sensor to determine amplitudes of component pulse waves of detected volume pulse waves of the limb segment detected during the baseline period to determine a baseline arterial volume of the limb segment, to determine amplitudes of component pulse waves of detected volume pulse waves of the limb segment detected during a time period after a stimulus has been applied to the mammal to induce a period of change in the arterial volume of the limb segment, and to determine relative change in arterial volume of the limb segment during the time period after the stimulus relative to the arterial volume of the limb during the baseline period from the amplitudes of the component pulse waves of the detected volume pulse waves at baseline and after the stimulus; and a pressure cuff coupled to the sensor and the processor to apply a stimulus to the mammal by inflating to a pressure above systolic for application to the limb segment for a period of time sufficient to induce change in arterial volume of the limb segment after releasing the inflation pressure of the cuff; wherein the processor controls the cuff to apply, in a series, an external pressure to the limb segment at a mean arterial pressure of the limb, and controls the sensor to detect volume pulse waves of the limb segment during the baseline and after the stimulus.
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36. A diagnostic system for assessing change in arterial volume of a limb segment of a mammal comprising:
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a sensor for detecting volume pulse waves of a limb segment during a baseline period and for detecting volume pulse waves of the limb segment during a period of an after-stimulus change in arterial volume; a processor coupled to the sensor to determine amplitudes of component pulse waves of detected volume pulse waves of the limb segment detected during the baseline period to determine a baseline arterial volume of the limb segment, to determine amplitudes of component pulse waves of detected volume pulse waves of the limb segment detected during a time period after a stimulus has been applied to the mammal to induce a period of change in the arterial volume of the limb segment, and to determine relative change in arterial volume of the limb segment during the time period after the stimulus relative to the arterial volume of the limb during the baseline period from the amplitudes of the component pulse waves of the detected volume pulse waves at baseline and after the stimulus; and a pressure cuff coupled to the sensor and the processor to apply a stimulus to the mammal by inflating to a pressure above systolic for application to the limb segment for a period of time sufficient to induce change in arterial volume of the limb segment after releasing the inflation pressure of the cuff; wherein the processor controls the cuff to apply an external pressure to the limb segment at a pressure level which allows blood flow through the artery to produce said volume pulse waves in response to the applied external pressure during the baseline and after the stimulus. - View Dependent Claims (37, 38, 39, 40, 41, 42)
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43. A diagnostic system for assessing change in arterial volume of a limb segment of a mammal comprising:
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a sensor for detecting volume pulse waves of a limb segment during a baseline period and for detecting volume pulse waves of the limb segment during a period of an after-stimulus change in arterial volume; and a processor coupled to the sensor to determine amplitudes of component pulse waves of detected volume pulse waves of the limb segment detected during the baseline period to determine a baseline arterial volume of the limb segment, to determine amplitudes of component pulse waves of detected volume pulse waves of the limb segment detected during a time period after a stimulus has been applied to the mammal to induce a period of change in the arterial volume of the limb segment, and to determine relative change in arterial volume of the limb segment during the time period after the stimulus relative to the arterial volume of the limb during the baseline period from the amplitudes of the component pulse waves of the detected volume pulse waves at baseline and after the stimulus; wherein the component pulse wave is an early systolic component; and wherein the processor computes a fourth derivative of the detected volume pulse wave, determines a time at which the fourth derivative reaches a third zero crossing, determines a pressure value on the detected volume pulse wave at said time, determines a pressure value at the beginning of the volume pulse wave, and assesses the amplitude of the early systolic component of the volume pulse wave as the difference between said pressures values to determine the amplitude of early systolic component of a volume pulse wave. - View Dependent Claims (44)
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45. A non-transitory machine-readable medium encoded with instructions, that when executed by one or more processors, cause the processor to carry out a process for assessing change in arterial volume of a limb segment of a mammal, the process comprising:
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determining amplitudes of component pulse waves of detected volume pulse waves of a limb segment detected during a baseline period to determine a baseline arterial volume of the limb segment; determining amplitudes of component pulse waves of detected volume pulse waves of the limb segment detected during a time period after a stimulus has been applied to the mammal to induce a period of change in the arterial volume of the limb segment; and determining relative change in arterial volume of the limb segment during the time period after the stimulus relative to the arterial volume of the limb during the baseline period from the amplitudes of the component pulse waves of the detected volume pulse waves at baseline and after the stimulus; wherein determining relative change in arterial volume of the limb comprises; calculating an average component pulse wave amplitude during the baseline period; generating a curve fit of component pulse wave amplitudes during the after-stimulus period; calculating a maximum of the fitted curve; determining a time between beginning of the after-stimulus period and the time of the maximum of the fitted curve; determining a relative amplitude change from the baseline to the maximum of the fitted curve; and determining a relative change in arterial volume from the relative amplitude change from the baseline to the maximum of the fitted curve and the average component pulse wave amplitude during the baseline period. - View Dependent Claims (46, 47, 48, 49)
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Specification