[Continuous monitoring of blood volume change by measuring hematocrit during cardiopulmonary bypass].

The usefulness of the continuous monitoring system of blood volume change (BV%), by using measured hematocrit, has been evaluated during cardiopulmonary bypass (CPB). Twelve patients for CABG were studied. The optical sensor was incorporated in the venous outlet site of CPB to measure Hct and hemoglobin oxygen saturation. The infusion of the cardioplegia caused a sharp deviation in BV%, and the use of extracorporeal ultrafiltration helped to reduce BV% rapidly. At the end of CPB, BV% was -1.4 +/- 7.7% and showed a good correlation with total water balance during CPB (r = 0.75, P < 0.01). However, the discrepancy between BV% and the positive water balance was observed in a case with LOS. This suggests fluid maldistribution from intra- to extra-vascular space. Continuous BV% monitoring during CPB is useful as an index of water balance and for assessing an optimum blood volume.