title: Cardiac output determinations with ear piece densitometry.
abstract: The results of cardiac output determinations by a dye dilution technique were compared using (a) a dichromatic earpiece which was calibrated as a flow-through cuvette, but also permitted automatic computing by virtue of a pressure capsule, and (b) an ordinary flow-through densitometer. Eleven subjects, some with cardio-pulmonary disease, were investigated. Cardiac outputs were systematically overestimated when automatically computed. The results obtained by manual calculation with the ear-piece corresponded more nearly with those derived from the flow-through cuvette, but still with a deviation from the identity line and with a residual standard deviation of 0.8 l/min. Double determinations had a residual standard deviation of 0.7 l/min. Despite its ease of handling, an earpiece densitometer seems to be too unreliable to be suitable for routine use.
mesh_terms: D000328:Adult; D000368:Aged; D000768:Anesthesia, General; D002302:Cardiac Output; D003201:Computers; D003720:Densitometry; D004395:Dye Dilution Technique; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011652:Pulmonary Circulation; D011660:Pulmonary Heart Disease / Q000503:physiopathology; D012121:Respiration, Artificial