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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 apparatus. A piezoelectric ultrasound transducer mounted on a probe and inserted into the trachea in great proximity to the aorta or pulmonary artery by passage through the oral nasal cavity past the epiglottis and into the trachea, or by passage through a 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 determined. 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. Balloons are provided to positively locate the probe in the trachea and to urge the ultrasound transducer(s) into intimate contact with the inner wall of the trachea.

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First Claim