title: Validation of a Doppler technique for beat-to-beat measurement of cardiac output.
abstract: We have measured aortic flow in the ascending aorta in man with a Bach-Simpson BVM 202 blood velocity meter, and aortic root diameter by M-mode echocardiography, and thus derived beat-to-beat cardiac output (Q). We tested the technique in 21 patients (53 comparisons) with various cardiovascular problems against a thermodilution method, and in four normal subjects at rest and two levels of exercise (50 and 100 W) against a nitrous oxide rebreathing method. We obtained excellent overall correlation in a range of 0.5-10 litres/min (r = 0.98, n = 77, sy,x = 0.48 litre/min), the formula for the least squares regression being: (Q Doppler) = 0.95 (Q Thermodilution/N2O) + 0.11 litre/min. The Doppler signal is sufficiently noise-free to obtain maximum acceleration of flow from the first derivative of velocity.
mesh_terms: D000328:Adult; D001011:Aorta; D001783:Blood Flow Velocity; D002302:Cardiac Output; D002318:Cardiovascular Diseases / Q000503:physiopathology; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D009609:Nitrous Oxide; D005082:Physical Exertion; D013815:Thermodilution; D014465:Ultrasonics
chemical_list: D009609:Nitrous Oxide