[Preoperative normvolemic hemodilution in heart surgery. Pulmonary changes with the use of new technics]

Interest in preoperative hemodilution (HD) has intensified perceptibly again, because of the increasing risk of adverse reactions to donor blood. However, in coronary surgery patients the use of HD is still the subject of controversy, as it may possibly influence organ function and especially lung water content. New techniques, including membrane oxygenation, extracorporeal circulation (ECC) with only "partial" bypass due to 2-stage cannulation, and hemoconcentration with cell separators, have significantly modified patient management in the field of cardiac surgery. Therefore, the influence of moderate hemodilution (12 ml/kg) on extravascular lung water (EVLW) was investigated under these conditions in 45 patients with coronary artery disease. Volume replacement was performed either with hydroxyethyl starch solution (HD-HES group, n = 15, ratio of replacement 1:1) or with Ringer's lactate (HD-RL-group, n = 15, ratio 2.5:1); 15 patients not subjected to HD served as controls. ECC was carried out with membrane oxygenators only in partial bypass. Both during and after ECC, blood was concentrated by means of a cell-saving system allowing separation and reinfusion of the red cells while the plasma is discarded. EVLW was measured using a double-indicator dilution technique with indocyanine green. Starting from comparable baseline values, EVLW was not significantly changed by hemodilution. After ECC, however, the HD-RL group showed a significant increase in lung water content (means: +2.49 ml/kg equal 42.6%), whereas this was not significantly changed in the other groups. By 5 h after ECC, the lung water content had returned to baseline values and no more differences could be observed between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)