BACKGROUND: Although hypothermia is known to have protective effects against ischemic injuries, the effects of hypothermia on kidney injury have not yet been elucidated. Therefore, this study aimed to identify the association between intraoperative hypothermia and postoperative acute kidney injury (AKI) in patients who underwent spine surgery under general anesthesia.
METHODS:In this retrospective observational study, we analyzed the medical records of adult patients who underwent elective spine surgery between January 2010 and March 2018. Patients were classified into the normothermia group (36.5 to 37.5°C), mild hypothermia group (35 to 36.5°C), and hypothermia group (<35°C) based on the mean intraoperative temperature, measured using an esophageal stethoscope. The association between mean intraoperative temperature and the incidence of postoperative AKI was analyzed using logistic regression analysis after inverse probability of treatment weighting (IPTW) adjustment.
RESULTS:The analysis included 6520 patients, of whom 248 (3.8%) were diagnosed with AKI within POD 3. After applying IPTW adjustment, the incidence of postoperative AKI was 32% lower in the hypothermia group than in the normothermia group (odds ratio, 0.68; 95% confidence interval, 0.53-0.87; P=0.002), whereas the incidence of postoperative AKI in the mild hypothermia group was not significantly different from that in the normothermia (P=0.139) and hypothermia groups (P=0.075).
CONCLUSIONS:This study showed that intraoperative hypothermia is associated with a reduction in the incidence of AKI following spine surgery under general anesthesia. Further, this association was evident in the group with hypothermia <35°C.