The diagnosis of acute renal failure (ARF) following cardiac surgery with cardio-pulmonary bypass.

The diagnostic value of renal concentrating capacity expressed as free water clearance (CH2O), in comparison with other routine criteria for the early identification of acute renal failure (ARF), was evaluated in 1,203 adult patients undergoing cardiac surgical procedures. On the basis of the appearance of pathologic CH2O values in the range of -20 to 0 ml/hour or more positive, reversible or irreversible ARF was observed in 90 (= 7.5%) of our patients. Mortality in the presence of ARF was 47%; total ARF mortality was 3.5%. CH2O was pathologic for the first time on an average of 1.6 days after operation. In contrast, routine ARF criteria reported in the literature, such as serum urea and creatinine at varying substrate levels or oliguria, allowed diagnosis 1 to 5.5 days later. Moreover, these parameters only partially and less frequently met the criteria for ARF at the different levels. Likewise, the incidence of ARF decreased to a minimum of 1.7% and the total ARF mortality to 1.3%, depending on the severity of the criteria used. Altogether, the occurrence of pathologic CH2O values proved to be the earliest, most frequent and most reliable criterion for the recognition of ARF following cardiac surgery with cardiac-pulmonary bypass.