Safe time limits of aortic cross-clamping and cardiopulmonary bypass in adult cardiac surgery

Abstract

We evaluated the impact of aortic cross-clamping time (XCT) and cardiopulmonary bypass time (CPBT) on the immediate and late outcome after adult cardiac surgery and attempted to identify their safe time limits. This study includes 3280 patients who underwent adult cardiac surgery of various complexities. Myocardial protection was achieved with tepid continuous antegrade/retrograde blood cardioplegia. Receiver operating characteristics (ROC) curve analysis showed that XCT (area under the curve, AUC: 0.66), CPBT (AUC: 0.73) and CPBT with unclamped aorta (AUC: 0.77) were significantly associated with 30-day postoperative mortality. XCT of increasing 30-minute intervals (Odds Ratio (OR) 1.21, 95%C.I. 1.01-1.52) and CPBT of increasing 30-minute intervals (OR 1.47, 95%C.I. 1.27-1.71) were independent predictors of 30-day mortality. The best cutoff value for XCT was 150 min (30-day death: 1.8% vs. 12.2%, adjusted OR 3.07, 95%C.I. 1.48-6.39, accuracy 91.5%) and for CPBT 240 min (30-day death: 1.9% vs. 31.5%, adjusted OR 8.78, 95%C.I. 4.64-16.61, accuracy 96.0%). These parameters were significantly associated also with postoperative morbidity, particularly with postoperative stroke. XCT and CPBT are predictors of immediate postoperative morbidity and mortality. In our experience, cardiac procedures with CPBT<240 min and XCT<150 min were associated with a rather low risk of immediate postoperative adverse events independently of the complexity of surgery patient's operative risk.