Acute renal failure following open heart surgery: risk factors and prognosis.

BACKGROUND: Acute renal failure (ARF) development after cardiac surgery carries high mortality and morbidity.
METHODS: Out of 14437 consecutive patients undergoing open-heart surgery between January 1991 and May 2001, 168 (1.16%) developed postoperative ARF mandating hemodialysis. Possible perioperative risk factors, and the prognosis of this dreadful, often fatal complication were investigated.
RESULTS: The mortality rate in this group was 79.7% (134 patients). The risk factors associated with postoperative ARF were advanced age (p=0.000), diabetes mellitus (p=0.000), hypertension (p=0.000), high preoperative serum creatinine levels (p=0.004), impaired left ventricular function (p= 0.002), urgent operation (p=0.000) or reoperation (p=0.007), prolonged cardiopulmonary bypass (CPB) (p =0.000) and aortic cross-clamp (ACC) (p =0.000) periods, level of hypothermia (p =0.000), concomitant procedures (p =0.000), low cardiac output state (p =0.000), re-exploration for bleeding or pericardial tamponade (p =0.000), and deep sternal or systemic infection (p = 0.000). Of those who could be discharged from hospital, renal functions were restored in 21 patients (12.5%); however, eight patients (4.7%) became hemodialysis dependent. The mean follow-up period was 5.7+/-3.2 years (range: 4 months to 13 years; a total of 195 patient-years), and 10-year survival was 58.6+/-10.2% in the discharged patients.
CONCLUSIONS: ARF development after cardiac surgery often results in high morbidity and mortality. Recognizing risk factors permits the timely institution of proper treatment, which is the key to reducing untoward outcomes.