Introduction: Acute renal failure is one of the most serious complications of cardiac surgery. We studied the long term survival and quality of life of patients with a complicated postoperative course after cardiac surgery requiring renal replacement therapy, since they represent a heavy burden on hospital resources.
Method: Out of 7846 consecutive cardiac surgical patients, 126 (1.6%) required postoperative renal replacement therapy. Their preoperative status and hospital course was compared with patients who had no need of postoperative renal replacement therapy. Only patients who were on preoperative dialysis were excluded from this study. A multivariate forward stepwise analysis was used to identify predictors of renal replacement therapy (SAS 1999 programme for statistical analysis). Long term (34 ± 18 months) follow up information was collected and quality of life and prevalence of deafness (because we use high doses furosemide in patients with an oligoanuric state) were assessed. The ethical committee approved the study and patients signed a written informed consent.
Results: Hospital mortality in the study group was 84/126 (66.6%) versus 118/7720 (1.5%) in the control population (P < 0.001). Predictors of renal replacement therapy (with odds ratio and 95% CI) were: blood transfusion (OR: 28.7 95% CI 8.9-92.8), emergency surgery (OR 4.2 95% CI 2.3-7.6), preoperative renal impairment (OR 3.7 95% CI 2.2-6.1), reopening (OR 2.9 CI 1.6-5.1), mitral valve disease (OR 2.6 CI 1.6-4.2), low ejection fraction (OR 2.1 CI 1.3-3.6), IABP positioning (OR 1.8 CI 1.07-3.2) and duration of CPB (OR 1.007 per minute 1.002-1.01).
Patients who underwent renal replacement therapy and were discharged from the hospital had an excellent long term follow up with 70% survival at 34 ± 18 months, with only 9.5% of survivors on dialysis, 28.6% complaining of moderate deafness and no other reported limitation in daily living.
Discussion: Blood transfusion represented a strong predictor of postoperative renal replacement therapy. This could be attributed to the known transfusion related renal damage or to the epi-phenomenon of a pre-existent anaemia and poor general condition with hypoxia affecting the kidney perioperatively. The hospital mortality of patients requiring renal replacement therapy is high. The long term survival of patients discharged from the hospital is excellent (70% at 3 years) with good quality of life.
1 Chertow GM, Lazarus JM, Christiansen CL, et al. Preoperative renal risk stratification. Circulation