Method for measuring cardiac output
First Claim
1. A method for determining total cardiac output of a mammalian heart, which comprises:
- a. placing a first sound transducer in proximity to the ascending aorta by passage into the trachea of the mammal,b. transmitting ultrasound waves from the first transducer toward the path of flow of blood in the ascending aorta,c. receiving the ultrasound waves reflected by the blood,d. measuring the average Doppler frequency difference between the transmitted waves and the reflected received waves,e. determining the cross-sectonal area of the ascending aortaf. determining the volumetric blood flow rate from such measurement and the cross-sectional area of the ascending aorta.
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Abstract
Blood flow in the aorta and pulmonary artery of a mammal, most typically a human, is measured volumetrically by a non-invasive, ultrasound method and apparatus. The method comprises placing a piezoelectric ultrasound transducer in the trachea in great proximity to the aorta or pulmonary artery by passage through the oral or nasal cavity past the epiglottis and into the trachea or by passage through the surgical opening into the trachea in the case of patients who have had a tracheotomy. Ultrasound waves are transmitted toward the path of flow of blood in the artery. Reflected waves are received. The average Doppler frequency difference between transmitted and received waves is measured. The cross-sectional size of the artery is measured. Blood flow rate is determined from the measurements. The apparatus comprises a tracheal tube or probe with one or two transducers mounted at one end the tube. The transducer(s) is (are) disposed to transmit ultrasound in selected directions. Electrical conductors extend from the transducers the length of the probe.
127 Citations
14 Claims
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1. A method for determining total cardiac output of a mammalian heart, which comprises:
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a. placing a first sound transducer in proximity to the ascending aorta by passage into the trachea of the mammal, b. transmitting ultrasound waves from the first transducer toward the path of flow of blood in the ascending aorta, c. receiving the ultrasound waves reflected by the blood, d. measuring the average Doppler frequency difference between the transmitted waves and the reflected received waves, e. determining the cross-sectonal area of the ascending aorta f. determining the volumetric blood flow rate from such measurement and the cross-sectional area of the ascending aorta. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for determining the volumetric rate of flow of blood in the ascending aorta of a human heart, which comprises:
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a. placing a first sound transducer in proximity to the ascending aorta by passage into the trachea, b. transmitting ultrasound waves from the transducer toward the path of flow of blood in the aorta in a direction within the range of 10°
-80°
with respect to the direction of the path of flow,c. receiving the ultrasound waves reflected by the blood, d. measuring the average Doppler frequency difference between the transmitted waves and the reflected waves, e. measuring the diameter of the aorta, and f. determining the volumetric blood flow rate from such measurements. - View Dependent Claims (10, 11, 12, 13, 14)
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Specification