A Better Predictor of Acute Kidney Injury After Cardiac Surgery: The Largest Area Under the Curve Below the Oxygen Delivery Threshold During Cardiopulmonary Bypass

Abstract

Background The aim of this study was to compare the predictive accuracy of acute kidney injury (AKI) after cardiac surgery using cardiopulmonary bypass for the largest area under the curve (AUC) below the oxygen delivery (DO 2 ) threshold and the cumulative AUC below the DO 2 threshold. Methods and Results From March 2017 to October 2019, 202 patients who had undergone cardiac surgery with cardiopulmonary bypass were enrolled. The perfusion parameters were recorded every 20 seconds, and the DO 2 (10×pump flow index [L/min per m 2 ]×[hemoglobin (g/dL)×1.36×arterial oxygen saturation (%)+partial pressure of arterial oxygen (mm Hg)×0.003]) threshold of 300 mL/min per m 2 was considered to define sufficient DO 2 . The nadir DO 2 , the cumulative AUC below the , and the largest AUC below the were used to predict the incidence of AKI. Postoperative AKI was observed in 12.4% of patients (25/202). By multivariable analysis, the largest AUC below the ≥880 (odds ratio [OR], 4.9; 95% CI, 1.2–21.5 [ P =0.022]), preoperative hemoglobin concentration ≤11.6 g/dL (OR, 7.6; 95% CI, 2.0–32.3 [ P =0.004]), and red blood cell transfusions during cardiopulmonary bypass ≥2 U (OR, 3.3; 95% CI, 1.0–11.1 [ P =0.041]) were detected as independent risk factors for AKI. Receiver operating curve analysis revealed that the largest AUC below the was more accurate to predict postoperative AKI compared with the nadir DO 2 and the cumulative AUC below the (differences between areas, 0.0691 [ P =0.006] and 0.0395 [ P =0.001]). Conclusions These data suggest that a high AUC below the is an important independent risk factor for AKI after cardiopulmonary bypass, which could be considered for risk prediction models of AKI.

Global Perspectives in Acute Kidney Injury: Japan

“…9 Regarding CS-AKI, several observational studies in Japan have reported AKI incidence rates of 12-55%. [10][11][12][13][14] These rates were also similar to those of other countries, 15 although the median age was over 70 years in most of the studies in Japan, which was higher than that of other countries. Taken together, the AKI incidence in Japan appears to be comparable to that of other countries despite the advanced age of patients in the Japanese studies.…”

Impact of Oxygen Delivery on the Development of Acute Kidney Injury in Patients Undergoing Valve Heart Surgery

“…DO2 dynamically changes during CPB. Oshita et al [ 25 ] found that both an extended and profound decline of DO 2 under the cutoff value of 300 mL/min/m 2 is preferable compared with established or fixed nadir DO 2 parameters in predicting CSA-AKI. In addition, preventing hemodilution and excessive transfusion and improving CPB pump flow are of paramount importance to maintaining a DO 2 over 300 mL/min per m 2 [ 26 ].…”

Preservation of renal endothelial integrity and reduction of renal edema by aprotinin does not preserve renal perfusion and function following experimental cardiopulmonary bypass

“…When interpreting these trials, it is important to consider that the incidence of AKI depends on studied cardiac surgical population, preoperative renal function status, and criteria used to define acute kidney injury. In addition, magnitude of tubular injury and occurrence of postoperative AKI appears independently associated with duration of CPB, duration of low oxygen delivery (DO 2 ) during CPB, and degree of rewarming [46,47].…”