Influence of cardiac output on thermal-dye extravascular lung water (EVLW) in cardiac patients.

The influence of varying cardiac output (CO) on thermal-dye extravascular lung water (EVLW) was investigated in a total of 40 cardiac surgery patients before the onset of the operation. EVLW was measured by means of the double indicator dilution technique with indocyanine green as the non-diffusible indicator and a microprocessed lung water computer 15 min and 30 min after change of CO. CO was varied from -45% to +70% of the baseline value by nifedipine infusion (CO increases, n = 20) or halothane application (CO decreases, n = 20), respectively. CO was measured from the femoral artery instream thermistor tipped lung water catheter and, simultaneously, from the pulmonary artery. In spite of a highly significant decrease (-45%) and increase (+70%) in CO no change in EVLW could be observed. CO estimation was comparable for both methods used. Regression analysis revealed no relationship between CO and EVLW as well as between EVLW and various hemodynamic parameters. We conclude that thermal-dye technique for estimation of EVLW may be accurate in spite of changing cardiac output over a wide range.