[Changes in water balance and kidney function caused by cardiopulmonary bypass].

The authors studied in 42 patients, 35 normotensives and 7 hypertensives, undergoing open-heart surgery, the perioperative behaviour of renal function and fluid balance. Before cardio-pulmonary bypass (CPB), there was a prerenal impairment of renal function caused by reduced fluid intake. During CPB a marked osmolal diuresis without tubular failure occurred. The amount of positive fluid balance was proportional to the duration of CPB. In those hypertensive patients in whom CPB perfusion pressure was below 50 mmHg, the creatinine clearance decreased by 67% during this period. The results indicate that the extent of CPB-induced renal dysfunction is tolerable and does not result in renal failure provided an adequate perfusion pressure is maintained. However, the consequences of marked water retention for undisturbed vital organ function must be taken into consideration.