Risk Factors for Acute Kidney Injury after Moderate Hypothermic Circulatory Arrest in Hemiarch Replacement

Background. The aim of this study was to clarify the incidence and risk factors for acute kidney injury (AKI) in patients undergoing hemiarch replacement (HAR) under moderate hypothermic circulatory arrest (MHCA) with retrograde cerebral perfusion (RCP). Methods. We retrospectively analyzed patients who underwent HAR under MHCA with RCP at our institution between April 2015 and July 2022. Exclusion criteria were preoperative dialysis, single kidney, and lack of preoperative plasma creatinine data. The study endpoint was the incidence of postoperative AKI, defined using the Kidney Disease: Improving Global Outcomes criteria. Multivariate logistic regression analysis was performed to identify the risk factors for postoperative AKI. Results. One hundred and seventy-nine patients were included in this study. The most common indications for HAR were thoracic aortic aneurysm (n = 107) and acute aortic dissection (n = 57). Concomitant procedures, most frequently aortic valve surgery, were performed in 104 (60.5%) patients. Median circulatory arrest time and minimum rectal temperature were 15 minutes (interquartile range, 11 to 19) and 27.4°C (interquartile range, 25.9 to 28.1), respectively. Operative mortality was 1.1%. The incidence of postoperative AKI was 37.8%. Multivariate analysis showed that acute aortic dissection (odds ratio, 4.57; 95% confidence interval (CI), 2.13–10.14; $P$ < 0.001) and longer operating time (odds ratio, 1.01; 95% CI, 1.00-1.01; $P$ = 0.001) were independent predictors for postoperative AKI. Conclusions. Acute aortic dissection and longer operating time were risk factors for postoperative AKI in patients undergoing HAR under MHCA with RCP. In contrast, neither circulatory arrest time nor minimum rectal temperature was a risk factor for AKI. This may be due to the short duration of circulatory arrest.