Trial of Oxygen Delivery on Cardiopulmonary Bypass and Major Clinical Outcomes

Abstract

BackgroundLow oxygen delivery (DO2) on cardiopulmonary bypass has been associated with acute kidney injury. We sought to determine the association of intraoperative DO2, postoperative length of stay, and major postoperative events. MethodsDO2 values were calculated in 845 patients after initiation, and every 30 minutes on bypass. Pump flows were increased for DO2 < 280 mL O2/min/m2, but care was not otherwise adjusted. Patients were retrospectively separated into 3 groups based on DO2 values: Group A, all readings ≥280 mL O2/min/m2; Group B, ≥1 reading <280 mL O2/min/m2; Group C, ≥2 readings <280 mL O2/min/m2. Patient outcomes were analyzed. ResultsWe analyzed 845 consecutive adult cardiac cases. Group B patients had a higher Society of Thoracic Surgeons Predicted Risk of Mortality compared with Group A (1.9% vs 1.2%, P < .001), and this effect was amplified for Group C patients (2.2%, P < .001). Postoperative length of stay was lowest for Group A patients (5.2 days) compared with Group B (6.6 days, P < .001) and Group C (7.0 days, P < .001). Overall complications rates were low, although Group A patients experienced lower rates of prolonged ventilation (3.5%) compared with Group B (6.5%, P = .04) and Group C (9.2%, P = .004). Multivariable regression analysis confirmed that DO2 above threshold was associated with significantly reduced rates of prolonged ventilation and postoperative length of stay. Other outcomes were similar between groups. ConclusionsEven a single DO2 value below threshold was associated with excess prolonged ventilation and postoperative length of stay, but not other outcomes.