Clinical experience with the use of computers for calculation of cardiac output

Abstract

1. 1. One hundred and seventeen cardiac output determinations were obtained in 12 patients with normal and abnormal cardiovascular systems. The dye curves were calculated by the hand method of Hamilton and with the use of a dye-dilution analog computer. 2. 2. There was a good agreement between the two methods with an average of the percentage difference of 8 per cent and with a standard deviation of 4.2 per cent. In curves with prolonged clearance time and low peak concentration, the average difference was 25.2 per cent with a standard deviation of 11.0 per cent. 3. 3. Changes in the cardiac output provoked by exercise, change in heart rate and by administration of drugs were adequately detected by the computer technic. 4. 4. It was found that the cardiac output computer is a time-saving, reliable and reproducible instrument in the calculation of the cardiac output. 5. 5. The computer should not be used in cases with low peak concentration, prolonged clearance time and in cases with any form of intracardiac shunt.