Incidence and predictors of ARDS after cardiac surgery

Background: Severe pulmonary injury with the development of ARDS is a potential complication of cardiac surgery and cardiopulmonary bypass (CPB). Study objectives: This retrospective, case-control study was designed to determine the incidence and mortality of ARDS after cardiac surgery and CPB, as well as to identify preoperative and perioperative predisposing factors of this complication. Methods: Of 3,278 patients who underwent cardiac surgery and CPB between January 1995 and December 1998, 13 patients developed ARDS during the postoperative period. Each patient was matched with four or five control subjects who had the same type of surgery on the same day but did not develop postoperative respirator complications. Results: The incidence of ARDS was 0.4%, with an ARDS mortality of 15%. In the ARDS group, 38% had previous cardiac surgery, as compared to 3.5% in the control group (p < 0.002). During the postoperative period, ARDS patients received more blood products (4 +/- 5 vs 2 +/- 3; p < 0.01) and developed shock more frequently (31% vs 5%; p < 0.02) than patients in the control group. Multivariate regression analysis identified previous cardiac surgery, shock, and the number of transfused blood products as significant independent predictors for ARDS, with odds ratios of 31.5 (p = 0.015), 10.8 (p = 0.03), and 1.6 (p = 0.03), respectively. Conclusions: ARDS following cardiac surgery and CPB was a rare complication that carried a 15% mortality rate. Previous cardiac surgery, shock, and number of blood products received are important predicting factors for this complication.