Rapid assessment of cardiac output and central blood volumes from indicator dilution curves without precalculation using programmable calculators

Abstract

The program described here provides complete analysis of the indicator dilution curve by incorporating densitometric calibration and logarithmic downslope fit for the widely used Hewlett-Packard 67/97 hand calculator series. Densitometric sensitivity is calculated from the linear regression as the dye calibration factor; thus, direct entry of the dye curve deflections eliminate the necessity to precalculate curve concentration. The program displays appropriate sequential time intervals prompting deflection entry of the upslope and initial exponential downslope of the curve. The remainder of the curve is generated from the logarithmically extrapolated initial downslope, and the area of the curve is then obtained for calculation of cardiac output, mean transit time, and central blood volume. Programming versatility and the rapid (4–5 min) immediate analysis of indicator dilution curves are thus available.