Abstract 17423: The Conundrum of Oxygen Delivery in Redo Cardiac Surgery: Prognostic Implications and Interactions With Major Predictors

Abstract

Introduction: Nadir oxygen delivery index (DO2i) during cardiopulmonary bypass (CPB) is a known independent predictor of Acute Kidney Injury (AKI) after routine cardiac surgery. Little is known about its prognostic role in the setting of redo procedures. Hypothesis: To define if Nadir DO2i is predictive of renal malperfusion in redo setting. Secondary outcomes were cardiac morbidity (composite of intra-aortic balloon pump or extracorporeal membrane oxygenation, use of continuous high dose inotropic support for at least 24 hours or autopsy evidence of heart failure), stroke and hospital mortality. Methods: All 398 consecutive patients (mean age of 62.1 ± 12.2 years, octogenarians 5.6%, female sex 47.4%, diabetes 20.1%, chronic kidney disease 31.2%, urgent/emergent status 26.2%, third-time sternotomy 9.8%; EuroSCORE II 10.5±11.2%) referred for a redo procedure (January 2011-January 2021) to a single tertiary care, university affiliated center were analyzed. The reliability of NadirDO2i to predict AKI was ascertained with AUC. The best cut-off was determined with the Youden index. The odds to incur in any of the predetermined outcomes was investigated with binary logistic regression. Interaction with known predictors of AKI (preoperative anemia, preoperative chronic kidney disease, older age, emergency status, baseline pathology, EuroSCORE II, need for CPB before sternotomy, blood transfusion during cardiopulmonary bypass) was also investigated. Results: Acute Kidney Injury (any grade) developed in 41.2 % (Risk 17.5%, Injury 8.0%, Failure 15.7%); cardiac morbidity developed in 53.2%, perioperative stroke in 2.8%. In-hospital mortality averaged 17.1%. Best Nadir DO2i predictor of AKI-Failure was 274 ml/min/m2 (AUC 0.644; 68.9% and 60.6% sensitivity and specificity, respectively). Same cut-off predicted cardiac morbidity and hospital mortality (OR 2.200, 95%CI 1.462-3.311 p=0.0002, and OR 4.677, 95%CI 2.577-8.488 p<0.0001, respectively). No interaction of Nadir DO2i emerged with predefined predictors. Conclusions: Nadir DO2i during cardiopulmonary bypass is independently associated with major postoperative morbidity and mortality in redo scenario and is not influenced by other nuances variables.