FAST ESTIMATION OF THE DILUTION CURVE AREA BY A PROCEDURE BASED ON A COMPARTMENTAL HYPOTHESIS.

A method is proposed for fast estimation of the area under the indicator dilution curve and, therefore, for calculation of cardiac output. Only measurement of buildup time and the maximum concentration are needed plus the assumption of a number (N) of compartments, the latter being dependent on the sites of injection and detection and, to a lesser extent, on the size of the animal. In all cases studied, this number was found to be either 3 or 4. The method has three advantages: it saves considerable time in calculation, either manually or by computer; it corrects for recirculation without using the simple exponential extrapolation; and it provides a theory with a functional interpretation. The disadvantage is an increase in variability of results.