Predictive Capacity of Oxygen Delivery During Cardiopulmonary Bypass on Acute Kidney Injury

Abstract

The randomized goal-directed perfusion trial confirmed retrospective findings that a goal-directed perfusion strategy to maintain oxygen delivery index (DO2i) during cardiopulmonary bypass greater than 280 mL/min/m2 reduces the incidence of acute kidney injury (AKI). We developed a predictive model for AKI using data from the Australian and New Zealand Collaborative Perfusion Registry to determine whether these findings could be validated in a real-world clinical setting and to identify an optimal DO2i threshold for predictive diagnostic accuracy. Data in 19,410 cardiopulmonary bypass procedures were randomly divided into training (n= 9705) and validation (n= 9705) datasets. Multivariate logistic regression was used to determine the best predictive models for AKI (RIFLE [renal Risk, Injury, Failure, Loss of renal function and End-stage renal disease] classification), incremental predictive value of minimum cardiopulmonary bypass DO2i, and optimal threshold. Minimum DO2i was significantly associated with any AKI, AKI risk, and AKI injury or greater class in both datasets (validation dataset; any AKI odds ratio [OR], 0.993; 95% confidence interval [CI], 0.991-0.995; P < .001; AKI risk OR, 0.994; 95% CI, 0.992-0.996; P < .001, AKI injury or greater 0.993; 95% CI, 0.991-0.996; P < .001), representing on average a 7% increase in the likelihood of AKI for every 10-mL/min/m2 decrease in DO2i. Diagnostic accuracy was similar for both datasets, with an optimal DO2i threshold of 270 mL/min/m2. The odds of any AKI were increased by 52% in those below the threshold (OR, 1.52; 95% CI, 1.29-1.77; P < .001). This study confirms previous findings that minimum DO2i during cardiopulmonary bypass is independently associated with AKI, supporting previous findings in a broader-risk, multicenter cohort.