Abstract:Objective To explore the effects of different doses of muscle relaxants on intraoperative body motor response， respiratory mechanics， and postoperative spontaneous breathing recovery in patients undergoing gynecological hysteroscopic surgery，and to provide a reference for the clinical dose selection of cisatracurium besilate. Methods A retrospective study was conducted on 180 patients who underwent hysteroscopic surgery at the Affiliated Chuzhou Hospital of Anhui Medical University from January 2021 to December 2021. All patients received intravenous general anesthesia. During anesthesia induction，60 patients received 0.05 mg/kg cisatracurium besilate as the low-dose group，60 patients received 0.15 mg/kg cisatracurium besilate as the normal-dose group，and 60 patients did not receive cisatracurium besilate as the control group. The following indicators were collected and compared：hemodynamic parameters including heart rate（HR），systolic blood pressure（SBP），and diastolic blood pressure（DBP）before anesthesia induction（T0），10 min after anesthesia induction（T1），at laryngeal mask airway insertion（T2），and 10 min after laryngeal mask airway insertion（T3）；respiratory mechanical parameters including partial pressure of end-tidal carbon dioxide （PetCO2），lung compliance，and airway pressure at 5 and 10 min after laryngeal mask airway insertion；body movement response，success rate of first-attempt laryngeal mask airway insertion，and time from drug withdrawal to spontaneous breathing recovery. Results There were statistically significant inter- time effects，inter-group effects，and interaction effects on HR，SBP，DBP，and lung compliance among the three groups（P＜0.05）. At time points T2 and T3，HR，SBP，and DBP in the normal-dose group and low-dose group were more stable than those in the control group（P＜0.05）. At 5 and 10 minutes after laryngeal mask airway insertion，there were no statistically significant difference in airway pressure and PetCO2 among the three groups（P＞0.05），while lung compliance in the normal-dose group and low-dose group was higher than that in the control group（P＜0.05）. There were statistically significant differences in body movement response（0，1.67%，15.00%; χ2=10.179，P＜0.05），first-time success rate of laryngeal mask airway insertion（96.67%，95.00%，81.67%; χ2=11.523，P＜0.01），and time from drug discontinuation to spontaneous respiration recovery［（20.43±2.20）min，（8.12±1.14）min，（5.07±1.18）min；F=1 588.011，P＜0.01］among the normal-dose group，low-dose group and control group. The body movement response in the normal-dose group and low-dose group was lower than that in the control group（P＜0.05），while the first-time success rate of laryngeal mask airway insertion was higher than that in the control group（P＜0.05）. The time from drug discontinuation to spontaneous respiration recovery in the normal-dose group was longer than that in the low-dose group and control group（P＜0.05）. Conclusion Low-dose cisatracurium besilate for anesthesia induction in gynecological hysteroscopic surgery is beneficial to improve lung compliance and reduce airway resistance，thereby increasing the success rate of first laryngeal mask airway insertion. At the same time，it can reduce movement response，and the time from drug withdrawal to spontaneous breathing recovery is relatively short，which has no adverse effect on postoperative recovery.