ABSTRACT
Preoperative hemodilution (HD) is an established blood-saving method. With HD, however, a concomitant increase in extracellular and interstitial water has been reported. This randomized study was undertaken to compare the effects of acute normovolemic HD (10 ml/kg; n = 15) using hydroxyethyl starch solution (HES) on extravascular lung water (EVLW) with those of an untreated control group (n = 15) of cardiac surgery patients submitted to extracorporeal circulation (ECC). A thermal-dye technique was used to measure EVLW. There was no significant change in EVLW due to preoperative HD (5.55 +/- 0.51 vs. 5.71 +/- 0.59 ml/kg). After ECC, a transient increase in both groups could be demonstrated because of a possible change in pulmonary capillary permeability (maximal increase in the HD group: +1.30 ml/kg and in the nonHD group: +1.02 ml/kg). Five hours after ECC, no differences could be seen between the groups. Pulmonary gas exchange was not significantly affected (PaO2 in the HD group: -20 torr). Hemodynamic and laboratory variables indicated the typical changes during HD (cardiac index increases while albumin concentration decreases); circulatory stability was maintained during the entire study. We conclude that preoperative normovolemic HD did not increase lung water content significantly nor compromise pulmonary function even in cardiac surgery patients. Although ECC provides an additional HD (crystalloid priming of the heart-lung bypass machine) and possibly damage of capillary integrity, the two groups did not differ.
