Requirement for renal replacement therapy in patients undergoing cardiac surgery

Background: Despite refinements in perioperative patient management renal insufficiency requiring renal replacement therapy (RRT) is still a common complication after cardiac surgical procedures associated with impaired patient outcome and increased costs. Methods: Prospective data on 16184 patients undergoing different cardiac surgical procedures (CABG, n = 8917; beating heart CABG, n = 1842 [OPCAB, n = 765; MIDCAB, n = 1077]; aortic valve surgery, n = 1830; mitral valve surgery, n = 708; double valve surgery, n = 381; CABG and valve surgery, n = 2506) between April 1996 and August 2001 were subjected to univariate and multivariate logistic regression analysis. Postoperative RRT was defined as any postoperative renal insufficiency requiring first time hemofiltration or dialysis during the postoperative stay. Patients with preoperative dialysis dependent renal insufficiency were excluded from further analysis. Results: The overall prevalence of postoperative RRT was 4.7% which varied according to different surgical procedures. 45 out of 49 selected pre- and intraoperative patient- and treatment-related variables had a significant association with postoperative RRT. 10 of these (renal disease, myocardial infarction, diabetes, cardiogenic shock, urgent operation, NYHA greater than or equal to 3, intraoperative hemofiltration, perfusion time greater than or equal to 2 hours, intraoperative low cardiac output, perioperative high transfusion requirement) were independent predictors. OPCAB surgery and younger patient age were identified as having a significantly lower predictive value for postoperative RRT. Patients with postoperative RRT were found to have a significantly longer ICU- and total postoperative hospital stay as well as a higher 30-day mortality. Conclusion: Identifying perioperative risk factors associated with postoperative RRT will help to reduce the incidence of this complication. Avoiding cardiopulmonary bypass seem to be beneficial with regard to the prevalence of postoperative RRT.