Evaluation of Indicator Dilution Curve Areas

Abstract

In 24 patients with aortic or mitral valvular disease, 130 thermal dilution and 106 dye dilution curves were recorded for determination of cardiac output. This was in the range of 2–8 1/min. Each curve area was calculated using 3 different methods. The first method (Kinsman et al.) requires semilogarithmic extrapolation of the downslope of the curve and planimetry. The second method (Hepner et al.) differs from the first by a simplified extrapolation. The third method (Bradley & Barr) is more rapidly performed requiring only a few manual measurements and no planimetry. There was no significant difference between the results obtained by the first and second methods, either for thermal or for dye dilution curves. There was no significant difference between the values obtained by the third and the two other methods concerning dye dilution curves, but the difference was significant concerning thermal dilution curves. The third method was modified by replacing the original empirical factor derived from selected dye dilution curve areas by new ones derived from the present material and then became suited for the calculation of unselected thermal and dye dilution curve areas.