Usefulness of Cardiac Power as a Predictor of Acute Kidney Injury in Cardiac Surgery Patients with Extracorporeal Circulation

Abstract

Introduction: Acute kidney injury (AKI), identified by elevated serum creatinine or reduced urine output, is a frequent complication following cardiac surgery. It is associated with hypoperfusion, embolic events, extracorporeal circulation–related injury, and nephrotoxic exposure, affecting up to 43% of adults and 52% of children. Methods: Adult patients undergoing cardiac surgery with extracorporeal circulation were included. AKI was defined according to KDIGO criteria (∆SCr > 0.3 mg/dL within 48 h, >1.5 × baseline within 7 days, or urine output < 0.5 mL/kg/h for 6 h). Data were collected prospectively, and inferential analyses (AUROC, odds ratios, chi-square with p < 0.05) were performed using SPSS v24.0. Sampling was conducted by convenience. The study adhered to national and international research ethics guidelines, including the Mexican General Health Law on Research. Results: Forty adults underwent cardiopulmonary bypass (mean age 65.8 ± 9.9 years; 75% male), with no exclusions. Serum creatinine increased from 1.11 ± 0.38 mg/dL at baseline to 2.39 ± 1.16 mg/dL at 48 hours. AKI developed in 34 patients (85%), distributed as stage I: 7.5%, stage II: 17.5%, and stage III: 60%. Cardiac power demonstrated predictive capacity for AKI, though AUROC analysis indicated negligible performance (AUC 0.093, p = 0.002). Conclusions: In patients undergoing cardiac surgery with cardiopulmonary bypass, mean cardiac output at ICU admission was 3.01 ± 1.12 L/min with cardiac power (CP) of 0.51 ± 0.26 W. AKI occurred in 85% of patients, predominantly stage III. A CP below 0.46 W doubled the risk of AKI regardless of stage, although its AUROC-based predictive performance remained negligible despite statistical significance.