Effect of different doses of esketamine on the median effective concentration of propofol for inhibiting body movement during hysteroscopy

The objective of this study is to investigate the effects of various doses of esketamine on the median effective concentration (EC₅₀) of propofol required for inhibiting body movement during hysteroscopy. Additionally, this research aims to explore the pharmacodynamic interactions between esketamine and propofol. Prospective, double-blind, up-down sequential allocation study. Operating room, post-anesthesia care unit (PACU), and general ward. A total of 90 patients were allocated into three groups in a randomized, double-blinded manner as follows: 0.1 mg/kg esketamine combined with propofol intravenous injection (EP_0.1) group, 0.2 mg/kg esketamine combined with propofol intravenous injection (EP_0.2) group, 0.3 mg/kg esketamine combined with propofol of intravenous injection (EP_0.3) group. For the initial patient in each group, the starting effector target concentration of propofol was set at 4 µg/ml. Each patient received an initial intravenous injection of 0.04 mg/kg midazolam, followed by the administration of the appropriate dose of esketamine. Ten seconds after the esketamine injection, propofol was administered intravenously to achieve the target concentration. In accordance with the sequential method principle, the concentration of propofol for the subsequent patient was adjusted based on the response of the previous patient. Effective inhibition of body movement was defined as the absence of any involuntary body movements throughout the entire surgical process. If the previous patient exhibited body movements, the propofol concentration for the next patient was increased by 0.5 µg/ml; conversely, if no movements were observed, it was decreased by 0.5 µg/ml. The up-down sequential allocation method and probit regression were used to calculate the EC₅₀ of propofol. Hospital Anxiety and Depression Scale-Anxiety (HADS-A) and Depression (HADS-D) score, adverse events, hemodynamic changes, demographic data and clinical characteristics. The EC₅₀ of propofol was 3.849 μg/ml (95% CI: 3.419-4.281) in the EP_0.1 group, 3.641 μg/ml (95% CI: 2.807-4.200) in the EP_0.2 group, and 3.417 μg/ml (95% CI: 2.845-3.852) in the EP_0.3 group. These findings suggest that esketamine can dose-dependently reduce the EC₅₀ of propofol. Esketamine can dose-dependently reduce the EC₅₀ of propofol in hysteroscopy, while concurrently lowering patients' HADS-A and HADS-D scores 24 h post-operation. It is concluded that the optimal dose of esketamine, when combined with propofol for hysteroscopy, is 0.3 mg/kg.