Predictors of acute renal failure after cardiac surgery

Introduction: Acute renal failure (ARF) is one of the major adverse events after cardiac surgical operations especially when using cardiopulmonary bypass. The aim of our investigation was to identify risk factors for ARF in patients with various preoperative creatinine levels. Methods: We retrospectively analyzed the data of 6872 patients who underwent cardiac surgery (73% CABG, 17% valves, 10% other). The majority of these patients 5831 (85%) came to surgery with normal preoperative creatinine serum levels of less than 1.2mg/dl. 859 (12.4%) showed creatinine levels between 1.3 to 2.0mg/dl and at a time 1.3% (n=91) of the patient's levels between 2.1 to 3.5mg/dl and above 3.5mg/dl respectively. Results: Acute renal failure occurred in 54 of the 5831 (0.93%) patients with preoperatively normal creatinine levels. The incidence of ARF increased to 5.25% (n=45) of the patients with moderate (1.3–2.0mg/dl) elevated creatinine and to 21% (n=19) of patients with significant (2.1–3.5mg/dl) elevated preoperative creatinine. Not unexpected the patients with preoperative end stage renal insufficiency (creatinine >3.5mg/dl) deteriorated in most of the cases (75%) and had to undergo dialysis. Multivariate analysis of independent risk factors resulted in significant maximum likelihood estimates for perfusion time, preoperative creatinine, norepinephrine but not for haemodynamic situation, preoperative use of diuretics or type of operation. Conclusion: Appearance of acute renal failure in patients without preexisting renal dysfunction is rare. Perfusion time, use of norepinephrine and preoperative serum creatinine are predictors for postoperative breakdown of renal function.