Original Articles

Low Oxygen Delivery as a Predictor of Acute Kidney Injury during Cardiopulmonary Bypass

Address correspondence to: Robert A. Baker, PhD, CCP, Cardiac & Thoracic Surgical Unit, Level 6 Flinders Private Hospital, Bedford Park, Adelaide, South Australia, 5042, Australia. E-mail: Rob.Baker@sa.gov.au

Received: 13 March 2017
Accepted: 10 July 2017

Abstract

Low indexed oxygen delivery (DO₂i) during cardiopulmonary bypass (CPB) has been associated with an increase in the likelihood of acute kidney injury (AKI), with critical thresholds for oxygen delivery reported to be 260–270 mL/min/m². This study aims to explore whether a relationship exists for oxygen delivery during CPB, in which the integral of amount and time below a critical threshold, is associated with the incidence of postoperative AKI. The area under the curve (AUC) with DO₂i during CPB above or below 270 mL/min/m² was calculated as a metric of oxygen delivery in 210 patients undergoing CPB. To determine the influence of low oxygen delivery on AKI, a multivariate logistic regression model was developed including AUC < 0, Euroscore II to provide preoperative risk factor adjustment, and incidence of red blood cell transfusion to adjust for the influence of transfusion. Having an AUC < 0 for an oxygen delivery threshold of 270 mL/min/m² during CPB was an independent predictor of AKI, after adjustment for Euroscore II and transfusion [OR 2.74, CI {1.01–7.41}, p = .047]. These results support that a relationship exists for oxygen delivery during CPB, in which the integral of amount and time below a critical threshold is associated with the incidence of postoperative AKI.