Osmolal excretion after open heart surgery

Abstract

SummaryWater and osmolal balance was investigated during the peri‐operative period in twenty unselected adult patients presenting for open heart surgery. On the day before surgery the mean urine output was 1.13 litres/sq m/24 hours and osmolal output 430 mOs/sq m/24 hours.Using a haemodilution cardiopulmonary bypass technique, patients received 2.62 litres/sq m and 792 mOs/sq m in the operating room. The pattern of excretion of this water and solute load was identified. Patients were still in positive balance on the day following surgery despite a considerable diuresis, with solute retention exceeding water retention.