Method and system for non-invasive ultrasound Doppler cardiac output measurement
First Claim
1. A method for the noninvasive measurement of cardiac output of a mammalian patient on a real time, beat-by-beat basis as a combined function of the cross-sectional area of the ascending aorta and the systolic velocity of blood flow therethrough, comprising the steps of:
- a. pulsedly insonifying the ascending aorta of said patient with repetitive, intermittent ultrasonic energy propagating along a line generally transverse with respect to the axis of said ascending aorta to define a first insonification zone;
b. receiving pulses of ultrasonic energy reflected from anatomical structure within said first insonification zone, including energy reflected from the anterior and posterior walls of said ascending aorta characteristic of the separation thereof along the transverse line of propagation;
c. discriminating said pulses of received ultrasonic energy to detect the transverse dimension of said ascending aorta between said anterior and posterior walls thereof;
d. developing an aortic diameter signal proportional to and indicative of said transverse dimension;
e. computing the cross-sectional area of said ascending aorta in the plane of said transverse line of propagation of pulsed energy;
f. continuously insonifying said ascending aorta with uninterrupted ultrasonic energy propagating along a line generally axial with respect to the axis of said ascending aorta to define a second insonification zone;
g. receiving Doppler-shifted ultrasonic energy reflected from pulsatile blood flow through said ascending aorta, frequency-shifted from said uninterrupted ultrasonic energy by values characteristic of systolic velocity of said blood flow;
h. developing a systolic velocity energy signal proportional to and indicative of said systolic velocity;
i. subjecting said systolic velocity energy signal to frequency spectrum analysis at a predetermined signal sampling rate to yield a velocity component profile signal;
j. integrating said velocity component profile signal over time for each period of said pulsatile flow to calculate a systolic velocity integral;
k. computing systolic volume as a combined function of said cross-sectional area and said systolic velocity integral;
l. computing cardiac output as the sum of said systolic volumes for n periods and dividing the sum by the time duration thereof.
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Abstract
A method and system for the noninvasive measurement of cardiac output of a mammalian patient on a real time, beat-by-beat basis as a combined function of the cross-sectional area of the ascending aorta and the systolic velocity of blood flow therethrough is comprised of the steps of and apparatus for pulsedly insonifying the ascending aorta of the patient with repetitive, intermittent ultrasonic energy propagating through the patient'"'"'s cardiac window; receiving pulses of ultrasonic energy reflected from the anatomical structure within the first insonification zone, including energy reflected from the aortic walls and characteristic of the dimensional separation thereof; developing an aortic diameter signal indicative of dimensional separation; computing the cross-sectional area of the ascending aorta therefrom; then continuously insonifying the ascending aorta with uninterrupted ultrasonic energy; receiving a Doppler-shifted ultrasonic energy signal reflected from pulsatile blood flow through the ascending aorta, and characteristic of systolic velocity of blood flow; subjecting the systolic velocity signal to a frequency spectrum analysis at a predetermined signal sampling rate to yield a velocity component profile signal; integrating the velocity component profile signal over time; computing systolic volume as a combined function of cross-sectional area and the systolic velocity integral for each of n cardiac cycles; and, computing cardiac output as the time-averaged sum of systolic volumes for the n periods.
126 Citations
23 Claims
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1. A method for the noninvasive measurement of cardiac output of a mammalian patient on a real time, beat-by-beat basis as a combined function of the cross-sectional area of the ascending aorta and the systolic velocity of blood flow therethrough, comprising the steps of:
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a. pulsedly insonifying the ascending aorta of said patient with repetitive, intermittent ultrasonic energy propagating along a line generally transverse with respect to the axis of said ascending aorta to define a first insonification zone; b. receiving pulses of ultrasonic energy reflected from anatomical structure within said first insonification zone, including energy reflected from the anterior and posterior walls of said ascending aorta characteristic of the separation thereof along the transverse line of propagation; c. discriminating said pulses of received ultrasonic energy to detect the transverse dimension of said ascending aorta between said anterior and posterior walls thereof; d. developing an aortic diameter signal proportional to and indicative of said transverse dimension; e. computing the cross-sectional area of said ascending aorta in the plane of said transverse line of propagation of pulsed energy; f. continuously insonifying said ascending aorta with uninterrupted ultrasonic energy propagating along a line generally axial with respect to the axis of said ascending aorta to define a second insonification zone; g. receiving Doppler-shifted ultrasonic energy reflected from pulsatile blood flow through said ascending aorta, frequency-shifted from said uninterrupted ultrasonic energy by values characteristic of systolic velocity of said blood flow; h. developing a systolic velocity energy signal proportional to and indicative of said systolic velocity; i. subjecting said systolic velocity energy signal to frequency spectrum analysis at a predetermined signal sampling rate to yield a velocity component profile signal; j. integrating said velocity component profile signal over time for each period of said pulsatile flow to calculate a systolic velocity integral; k. computing systolic volume as a combined function of said cross-sectional area and said systolic velocity integral; l. computing cardiac output as the sum of said systolic volumes for n periods and dividing the sum by the time duration thereof. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A system for the noninvasive measurement of cardiac output of a mammalian patient on a real time, beat-by-beat basis as a combined function of the cross-sectional area of the ascending aorta and the systolic velocity of blood flow therethrough, comprising:
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a. pulse-echo transducer means for developing repetitive, intermittent bursts of ultrasonic energy and applying same to said patient to define a first insonification zone enveloping the region of the ascending aorta of said patient and for detecting energy reflected from the anatomical structure within said first insonification zone, including the anterior and posterior walls of said ascending aorta; b. pulse transmitter means for exciting said pulse-echo transducer to develop said bursts of energy; c. pulse receiver means for developing an echo signal proportional to and indicative of detected energy; d. operator-interactive visual display means for presenting control and display capabilities, including a graphic, scaled display of echo signals representative of the spatial conformation of said anatomical structure and signal strength representative of pulsatile blood flow therethrough; e. measurement means in operative association with said visual display means for determining the spatial separation between anterior and posterior walls represented on said scaled display, to develop an aortic diameter signal, f. area processor means receiving said aortic diameter signal for determining the cross-sectional area of said ascending aorta; g. continuous wave transducer means for developing uninterrupted ultrasonic energy and applying same to define a second insonification zone within said region of said ascending aorta and for detecting Doppler-shifted energy reflected from pulsatile blood flow therethrough; h. continuous wave transmitter means for exciting said continuous wave transducer to develop said uninterrupted ultrasonic energy at a continuous wave transmitter frequency; i. continuous wave receiver means for developing a Doppler signal having a frequency shift from said continuous wave transmitter frequency proportional to and indicative of the systolic velocity of said pulsatile blood flow; j. converter means for processing said Doppler signal to an audio frequency systolic velocity energy signal; k. spectrum analyzer means receiving said systolic velocity energy signal for developing a frequency domain velocity component profile signal characteristic of the velocity profile of systolic flow over an observed cardiac cycle; l. velocity processor means receiving said velocity component profile signal for computing the time integral thereof over the period of said caridac cycle, in accordance with an adaptive algorithm stored therein, to yield a systolic velocity integral signal and a stroke volume signal as a function of said cross-sectional area and said stroke volume; and
,m. cardiac output processor means receiving said stroke volume signal and a heart rate signal for determining cardiac output as the time-averaged sum of a plurality of cyclic stroke volumes. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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Specification