Lean body weight-indexed O 2 delivery during cardiopulmonary bypass and acute kidney injury

Introduction Monitoring indexed oxygen delivery (DO 2 i) is recommended during cardiopulmonary bypass (CPB) and a predictor of acute kidney injury (AKI). The use of lean body mass-adjusted blood flow rates in obese patients during CPB may provide a valid representation of metabolic demand, however, the risk of AKI with this approach has not been reported. This study aimed to investigate the influence of lean body mass-adjusted DO 2 i values in the risk of AKI following CPB. Methods Utilizing the Australian and New Zealand Collaborative Perfusion Registry dataset, 12,811 cardiac patients were divided into 2 groups; non-obese (BMI 30). Obese patients’ lean mass was derived from their recalculation to a BMI of 25 and used for the calculation of DO 2 i. Postoperative AKI was classified using the RIFLE criteria. Results Incidence of AKI was higher in the obese compared to non-obese group (15% vs 11%, p < 0.001). Decreasing minimum lean body weight adjusted DO 2 i was significantly associated with an increased risk of AKI (OR, 0.998; [0.997–0.999], p < 0.001) with an optimal threshold value of 292 ml/min/m 2 . Conclusions Lean body weight-adjusted O 2 delivery remains an independent risk factor for AKI. The critical minimum DO 2 i threshold of 292 mL/min/m 2 is within the range of previously reported values, inferring that lean-based blood flow monitoring may offer a reasonable approach to CPB practice.