Age and cardiac surgery. Influence on extravascular lung water

This study was designed in order to evaluate the influence of advanced age on extravascular lung water (EVLW) content. Forty patients undergoing aortocoronary bypass grafting were prospectively divided into two groups according to age below 45 years (group 1; n = 20) and above 65 years (group 2; n = 20). The EVLW was measured using the double indicator dilution technique with indocyanine green as the nondiffusible indicator. Starting from similar baseline values before extracorporeal circulation (ECC), EVLW significantly increased after ECC only in the elderly patients (max + 1.51 ml/kg), whereas lung water content in the other group remained almost unchanged. No significant differences in left ventricular filling pressure (PCP) could be observed. Regression analysis revealed a strong positive correlation between age and increase in EVLW after ECC. Simultaneously, PaO2 was decreased (-114 mm Hg) and intrapulmonary shunt fraction (Qs/Qt) was increased only in this group. Within the next five hours after ECC, lung water returned nearly to baseline values and pulmonary function was normalized. It is concluded that increasing age was associated with a transient increase in EVLW after ECC due to a more pronounced fragility of the pulmonary endothelial membrane or/and to depressed left ventricular performance.