• Jiang-Hua Shen, Min Ye, Qian Chen, Yan Chen, Hai-Lin Zhao, Ameena Khan, Bin Yi, Jiao-Lin Ning, Kai-Zhi Lu, and Jian-Teng Gu.
• Department of Anesthesiology, Southwest Hospital, Third Military Medical University (Army Medical University), No.30 Gaotanyan Road, Shapingba district, Chongqing, China.
• BMC Anesthesiol. 2021 Sep 6; 21 (1): 215.

BackgroundThe effects of circadian rhythms on drug metabolism and efficacy are being increasingly recognized. However, the extent to which they affect general anesthesia remains unclear. This study aims to investigate the effects of circadian rhythms on anesthetic depth and the concentrations of propofol target-controlled infusion (TCI).MethodsSixty patients undergoing laparoscopic surgeries were sequentially assigned to four groups. Group ND (n = 15): Propofol TCI with Narcotrend monitor during the day (8:00-18:00), Group NN (n = 15): Propofol TCI with Narcotrend monitor during the night (22:00-5:00), Group CLTD (n = 15): Propofol closed-loop TCI guided by bispectral index (BIS) during the day (8:00-18:00), Group CLTN (n = 15): Propofol closed-loop TCI guided by BIS during the night (22:00-5:00). The Narcotrend index, mean arterial pressure (MAP) and heart rate (HR) were compared between group ND and NN at 7 time points, from 5 min before induction to the end of operation. The propofol TCI concentrations, MAP and HR were compared between group CLTD and CLTN at 7 time points, from 5 min after induction to the end of operation.ResultsThe Narcotrend index, MAP, and HR in group NN were lower than those in group ND from the beginning of mechanical ventilation to the end of operation (p < 0.05). The propofol TCI concentrations in group CLTN were lower than those in group CLTD from the beginning of operation to the end of operation (p < 0.05).ConclusionCircadian rhythms have a significant effect on the depth of anesthesia and drug infusion concentrations during propofol TCI. When using general anesthesia during night surgery, the propofol infusion concentration should be appropriately reduced compared to surgery during the day.Trial RegistrationThe present study was registered on the ClinicalTrials.gov website ( NCT02440269 ) and approved by the Medical Ethics Committee of Southwest Hospital of Third Military Medical University (ethics lot number: 2016 Research No. 93). All patients provided informed written consent to participate in the study.© 2021. The Author(s).

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