The Determination of Cardiac Output by the Dilution Method without Arterial Sampling

Technics for determining the cardiac output by recording the dilution curve of injected iodinated I 131 human serum albumin from precordial sites have been described. By viewing predominantly either the right or left side of the heart and by rapid delivery of the isotope, quantitation of the dilution curves for cardiac output has been possible without critical requirements for placement of the counter. In a series of 26 determinations in normal patients cardiac output values calculated from simultaneously recorded precordial curves and withdrawn arterial blood showed an average agreement within ± 8 per cent. In a smaller series of 8 determinations on patients in heart failure, an average deviation of ± 9 per cent was found.