Background and Goal of Study: Acute renal failure (ARF) after cardiac surgery is a cause of major morbidity and mortality (1). Only some patients with ARF require renal replacement therapy (RRT). Our objectives are: 1) to assess the incidence and outcome of ARF after surgery with cardiopulmonary bypass (CPB) and 2) to identify the predictors factors for ARF requiring RRT (ARF-RRT).
Methods: Demographic and perioperative data in 544 consecutive patients undergoing cardiac surgery with CPB from January 1, 2002 to December 28, 2002 were recorded and entered into a computerized database. ARF was defined as a rise in serum creatinine above 120 μmol/l or a twofold rise of baseline value. RRT was indicated on clinical and biological grounds. Data were analyzed using Student's t-test, Chi-squared test and linear regression analysis, where appropriate.
Results: 65 patients (11.9%) had ARF; 21 of these (3.7% overall) developed ARF-RRT. In-hospital mortality in patients with ARF was 20% vs. 3.8% in those who did not develop ARF (p < 0.001); in patients with ARF-RRT was 52.4% vs. 4.5% in those who did not required RRT (p < 0.001). In patients with ARF-RRT who became anuric, in-hospital mortality was 77% vs. 12.5% in those with conserved diuresis (p < 0.001). In ARF patients the predictors of ARF-RRT included the following: post CPB inflammatory syndrome (p < 0.01), association between post CPB inflammatory syndrome and low cardiac output (CO) (p < 0.01), association between post CPB inflammatory syndrome and high doses of vasoconstrictors (p < 0.01). The association between low CO and high doses of vasoconstrictors is not a predictor of ARF-RRT. Anuria in patients with ARF-RRT correlated with age (p < 0.05), preoperative NYHA class status above III (p < 0.05), low CO after CPB (p < 0.05), and association between low CO and high doses of vasoconstrictors (p < 0.05).
Conclusions: ARF is a frequent complication after cardiac surgery with a high in-hospital mortality. In patients with ARF, post CPB inflammatory syndrome alone or in association with low CO after CPB or high doses of vasoconstrictors are correlated with ARF-RRT. There is a significant association between anuria and age, preoperative NYHA class status and low CO after CPB.
1 Mangano CM.: Ann Intern Med 128: 194-203, 1998.