ESTIMATION OF EXTRAVASCULAR LUNG WATER IN HUMANS WITH USE OF (H2O)-H-2 - EFFECT OF BLOOD-FLOW AND CENTRAL BLOOD-VOLUME

In the present human study we evaluated a newly developed double-indicator-dilution densitometric system for the estimation of cardiac output (Q), central blood volume (CBV), and extravascular lung water (EVLW) by using indocyanine green and heavy water ((H2O)-H-2) as indicators. Eighteen cardiopulmonary healthy patients scheduled for abdominal surgery were studied. A routine anesthesia procedure was used [thiopental (3-5 mg/kg), N2O (inspired fraction of O-2 = 0.4), and isoflurane (end tidal 0.5-1.5%)]. Q, CBV, and EVLW were measured at seven defined data collection points: awake, anesthetized spontaneously breathing, apneic, mechanically ventilated with and without positive end-expiratory pressure, postoperatively anesthetized, and postoperatively awake. During the whole study EVLW (3.8 +/- 0.9 ml/kg) was stable in the presence of large fluctuations in Q (2.5-10.1 l/min) and CBV (0.8-2.4 l). We concluded that the method is versatile and of low invasiveness, allowing reliable on-line Q and EVLW data for repeated measurements in the clinical setting.