Method and apparatus for noninvasive determination of cardiac output
First Claim
1. A method for determining the cardiac index of a living being, the method comprising:
- sensing a series of electrocardiac first signals sensed at a first location on the skin surface of the living being adjacent to the heart for use as synchronizing and timing signals;
sensing a series of second signals sensed at a second location on the skin surface of the living being that are related to instantaneous blood flow;
processing the first signals to obtain an average heart rate value by averaging the durations between successive "R" lines of each electrocardiac wave;
processing the second signals to obtain a blood flow waveform signal corresponding to instantaneous blood flow at the second location;
measuring the time from each "R" line signal to a predetermined point on the corresponding blood flow waveform signal to determine at least one corresponding pulse delay timing value; and
processing the average heart rate value and the pulse delay timing value to obtain a final value representing the cardiac index of the living being.
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Abstract
A determination of cardiac output of a living being is obtained noninvasively from measurements of heart rate and pulse timing points from a blood flow waveform in relation to the "R" line from a corresponding ECG signal. The blood flow waveform may be obtained indirectly, by differentiating the output of a plethysmograph or an instantaneous blood pressure sensor or by integrating the output of a doppler sensor, or indirectly from a magnetic flowmeter, for example. Heart rate and an "R" line trigger signal may be obtained from an electrocardiogram signal. Experimentally obtained heart rate and pulse timing data were compared with invasively measured cardiac output and were processed by regression analysis to yield an equation correlation of 0.73.
132 Citations
14 Claims
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1. A method for determining the cardiac index of a living being, the method comprising:
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sensing a series of electrocardiac first signals sensed at a first location on the skin surface of the living being adjacent to the heart for use as synchronizing and timing signals; sensing a series of second signals sensed at a second location on the skin surface of the living being that are related to instantaneous blood flow; processing the first signals to obtain an average heart rate value by averaging the durations between successive "R" lines of each electrocardiac wave; processing the second signals to obtain a blood flow waveform signal corresponding to instantaneous blood flow at the second location; measuring the time from each "R" line signal to a predetermined point on the corresponding blood flow waveform signal to determine at least one corresponding pulse delay timing value; and processing the average heart rate value and the pulse delay timing value to obtain a final value representing the cardiac index of the living being. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. Apparatus for determining the cardiac index of a living being, the apparatus comprising:
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means for sensing a series of electrocardiac first signals sensed on the skin surface of the living being; means for sensing a series of second signals on the skin surface of the living being related to instantaneous blood flow; means for processing the first signal to obtain an average heart rate value by averaging the times between successive "R" lines of each electrocardiac wave; means for processing the second signals to obtain a blood flow waveform signal; means for measuring the time from each "R" line signal to at least one predetermined point on the corresponding blood flow waveform signal to obtain at least one corresponding pulse delay timing value; and means for processing the average heart rate value and the pulse delay timing value to obtain a final value representing the cardiac index of the living being. - View Dependent Claims (11, 12, 13, 14)
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Specification