Daniel I Sessler, Lijian Pei, Kai Li, Shusen Cui, Matthew T V Chan, Yuguang Huang, Jingxiang Wu, Xuemei He, Gausan R Bajracharya, Eva Rivas, Carmen K M Lam, Yaozhong Zhang, Hai Sun, Zhouting Hu, Wangyu Li, Yangdong Han, Wei Han, Pengcheng Zhao, Hong Ye, Peng Chen, Zhihua Zhu, Weisong Dai, Lei Jin, Wenchao Bian, Yan Liu, Beaker B Y Fung, Eva Lee, Ka Yan Hui, Gordon Y S Choi, Wai Tat Wong, Chee Sam Chan, Yi Xiao, Bin Wu, Weiming Kang, Ling Lan, Chen Sun, Yuwei Qiu, Wei Tang, Yunyun Zhang, Qi Huang, Xiaofei Lu, Tingting Li, Qimeng Yu, Jie Yu, Rurong Wang, Hong Chang, Yunxia Zuo, Zhirong Sun, Wenting Hou, Congxia Pan, Xi Liu, Xue Zhang, Sheng Wang, Yin Kang, Zhengliang Ma, Xiaoping Gu, Changhong Miao, Mauro Bravo, Andrea Kurz, Alparslan Turan, Kurt Ruetzler, Kamal Maheshwari, Guangmei Mao, Yanyan Han, Ece Yamak Altinpulluk, Mateo Montalvo Compana, Federico Almonacid-Cardenas, Steve M Leung, CeCelia K Hanline, David M Chelnick, Marianne Tanios, Michael Walters, Michael J Rosen, Stephanie Ezoke, Edward J Mascha, Benny C P Cheng, Renee P L Yip, and P J Devereaux
Moderate intraoperative hypothermia promotes myocardial injury, surgical site infections, and blood loss. Whether aggressive warming to a truly normothermic temperature near 37°C improves outcomes remains unknown. We aimed to test the hypothesis that aggressive intraoperative warming reduces major perioperative complications.In this multicentre, parallel group, superiority trial, patients at 12 sites in China and at the Cleveland Clinic in the USA were randomly assigned (1:1) to receive either aggressive warming to a target core temperature of 37°C (aggressively warmed group) or routine thermal management to a target of 35·5°C (routine thermal management group) during non-cardiac surgery. Randomisation was stratified by site, with computer-generated, randomly sized blocks. Eligible patients (aged ≥45 years) had at least one cardiovascular risk factor, were scheduled for inpatient non-cardiac surgery expected to last 2-6 h with general anaesthesia, and were expected to have at least half of the anterior skin surface available for warming. Patients requiring dialysis and those with a body-mass index exceeding 30 kg/mBetween March 27, 2017, and March 16, 2021, 5056 participants were enrolled, of whom 5013 were included in the intention-to-treat population (2507 in the aggressively warmed group and 2506 in the routine thermal management group). Patients assigned to aggressive warming had a mean final intraoperative core temperature of 37·1°C (SD 0·3) whereas the routine thermal management group averaged 35·6°C (SD 0·3). At least one of the primary outcome components (myocardial injury after non-cardiac surgery, cardiac arrest, or mortality) occurred in 246 (9·9%) of 2497 patients in the aggressively warmed group and in 239 (9·6%) of 2490 patients in the routine thermal management group. The common effect relative risk of aggressive versus routine thermal management was an estimated 1·04 (95% CI 0·87-1·24, p=0·69). There were 39 adverse events in patients assigned to aggressive warming (17 of which were serious) and 54 in those assigned to routine thermal management (30 of which were serious). One serious adverse event, in an aggressively warmed patient, was deemed to be possibly related to thermal management.The incidence of a 30-day composite of major cardiovascular outcomes did not differ significantly in patients randomised to 35·5°C and to 37°C. At least over a 1·5°C range from very mild hypothermia to full normothermia, there was no evidence that any substantive outcome varied. Keeping core temperature at least 35·5°C in surgical patients appears sufficient.3M and the Health and Medical Research Fund, Food and Health Bureau, Hong Kong.For the Chinese translation of the abstract see Supplementary Materials section.