Acute Renal Failure in Adult Patients after Cardiac Surgery: Incidence, Risk Factors, and Associated Mortality Rate in Critical Care Unit
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- Category: Vol. 78, December 2010
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Acute Renal Failure in Adult Patients after Cardiac Surgery: Incidence, Risk Factors, and Associated Mortality Rate in Critical Care Unit,AHMED A. OSMAN, MOHSEN S. ABD ELAZEEM, AKRAM ALLAM and FAREED KHOUQEER
Abstract
Background: Acute renal failure (ARF) requiring contin-uous renal replacement therapy (CRRT) is a devastating complication post cardiac surgery, with an estimated incidence of 2-15% and is associated with high in-hospital mortality.
Aims of the Study: To determine the incidence, main risk factors, and in-hospital morbidity and mortality rate for patients who developed acute renal failure post cardiac surgery and who had normal renal profile preoperatively.
Methods: A retrospective, comparative case-control study was implemented between January 01, 2007 and June 30, 2008. A total of 680 consecutive adult patients who underwent cardiac surgery with cardiopulmonary bypass (CPB) at the King Faisal Heart Institute (KFHI) were retrospectively reviewed. Of these, 42 patients (6%) were identified as having renal impairment after cardiac surgery. However, only 29 patients met the inclusion criteria for the study, since 13 patients had pre-operative renal impairment and hence, were excluded from any subsequent analysis. As a control group, we randomly selected 51 patients who did not develop renal failure after cardiac surgery.
Results: Twenty-two patients (75.9%) in the study group underwent elective surgery. Valve surgery was the most common procedure in both groups (12, 41% for the study group and 28, 54.9% for the control group). CABG surgery was performed in 9 patients (31%) in the study group compared with 18 patients (35.3%) in the control group; valve surgery plus CABG was performed in 5 patients (17.2%) in the study group compared with one patient (2%) in the control group. In the study group the incidence of acute ARF after cardiac surgery was 4.3% (29/680). Of those, 25 out of 29 patients required continuous renal replacement therapy (CRRT) after surgery due to persistent oliguria, metabolic acidosis, hyper-volemia, and hyperkalemia that did not respond to other forms of therapy. The in-hospital mortality was high 69% (20 patients died out of 29). Preoperative variables that were significantly associated with ARF were advanced age, history of congestive heart failure with low ejection fraction, high Euro Score, and high normal pre-operative serum creatinine level. Significant operative and post-operative variables associated with devel-opment of postoperative ARF were emergency surgery, the use of Intra-aortic balloon pump (IABP), prolonged cardiop-ulmonary bypass time (CPB) and cross clamping time, hemo-dynamic complications (low cardiac output, hypoperfusion with requirement for inotropic support and/or vasopressors), development of systemic sepsis, post-operative bleeding, and prolonged ventilation.
Conclusions: The development of ARF after cardiac surgery is associated with high mortality. Preoperative risk factors associated with postoperative development of ARF include advanced age, history of congestive heart failure with low ejection fraction, high EuroScore, and high normal pre-operative serum creatinine. The operative and post-operative risk factors include emergency surgery, the use of IABP, prolonged CPB and cross clamping time, hemodynamic complications (low cardiac output, hypoperfusion), develop-ment of systemic sepsis, postoperative bleeding, and prolonged ventilation. Preventive measures can be planned ahead in order to achieve better results, diminish these complications, reduce mortality, save hospital costs and decrease total hospital stay.