[Double indicator dilution method using heat and dye to measure pulmonary extravascular water volume]

Abstract

It is widely accepted that extravascular lung thermal volume estimated by the double indicator dilution method with heat as a diffusible indicator reliably reflects pulmonary extravascular water volume. Theoretically, as a premise, the indicator should be preserved during its pulmonary circulation. We therefore investigated the thermal conservation during pulmonary circulation; that is, whether there was good agreement in the cardiac outputs "wherever" the thermodilution curves were recorded; for instance, the pulmonary artery trunk (PAT), giving COPAT,heat and the aortic root (Ao), giving COAo,heat. In the present study, we observed a total of 59 pairs of cardiac outputs in dogs (n = 13), including dogs with overt pulmonary edema, produced either by dextran infusion or by alloxan administration. We also studied a total of 23 pairs of cardiac outputs of human subjects (n = 16) with ischemic heart disease or mild mitral stenosis. A mixture of ice-cold 5% glucose solution and indocyanine green was rapidly injected into the right atrium. The thermodilution curve was immediately recorded in the pulmonary artery trunk, and the thermodilution and dye dilution curves were recorded in the aorta using a conventional Swan-Ganz catheter. The cardiac outputs were calculated manually following the Stewart-Hamilton principle. The results were as follows: In dogs, COPAT,heat averaged 2.47 +/- 1.21 L/min (mean +/- SD), COAo,heat averaged 2.44 +/- 1.12 L/min and the difference was not significant (0.3 less than p less than 0.5). The regression equation was COPAT,heat = 1.01 X COAo,heat + 0.02 (n = 59, r = 0.93, p less than 0.001) and the correlation coefficient was excellent.(ABSTRACT TRUNCATED AT 250 WORDS)