Association between cardiopulmonary bypass time and clinical outcomes among patients with acute respiratory distress syndrome after cardiac surgery

Abstract Background:Cardiopulmonary bypass (CPB) can lead to lung injury and even acute respiratory distress syndrome (ARDS) through triggering systemic inflammatory response. The objective of this study was to investigate the impact of CPB time on clinical outcomes in patients with ARDS after cardiac surgery. Methods:Totally, patients with ARDS after cardiac surgery in Beijing Anzhen Hospital from January 2005 to December 2015 were retrospectively included and were further divided into three categories according to CPB time during operation. The primary endpoints were the ICU mortality and in-hospital mortality, and ICU and hospital stay. Restricted cubic spline (RCS), logistic regression, cox regression model, and receiver operating characteristic (ROC) curve were adopted to explore the relationship between CPB time and clinical endpoints. Results: Of the 54217 patients who underwent cardiac surgery during the above period, 210 patients developed ARDS after surgery and were finally included. The ICU mortality and in-hospital mortality were 21.0% and 41.9% in all ARDS patients after cardiac surgery respectively. Patients in category3 (CPB time ≥ 173 minutes) had longer ICU stay (P=0.011), higher ICU (P<0.001) mortality and in-hospital(P=0.002) mortality compared with those in category1 (CPB=0). For each ten minutes increment in CPB time, the hazards of a worse outcome increased by 13.3% for ICU mortality and 9.3% for in-hospital mortality after adjusting for potential factors.ROC curves showed CPB time presented more satisfactory power to predict mortality compared with APCHEII score. The optimal cut-off value of CPB time were 160.5 minutes for ICU mortality and in-hospital mortality. Conclusion: Our findings firstly revealed the quantitative relationship between CPB time and clinical outcomes in patients with ARDS after cardiac surgery. Longer time of CPB was associated with poorer clinical outcomes, and could be served as an indicator to predict short-term mortality in patients with ARDS after cardiac surgery.