ABSTRACT
Objective:To evaluate the effect of lidocaine on the dose-effect relationship of remimazolam combined with alfentanil in inhibiting responses to gastroscope insertion in elderly patients.Methods:American Society of Anesthesiologists Physical Status classification Ⅰ or Ⅱelderly patients of either sex, aged 65-80 yr, with body mass index of 18-28 kg/m 2, undergoing painless gastroscopy under general anesthesia, were divided into 2 groups using a random number table method: remimazolam group (group C) and lidocaine combined with remimazolam group (group L). Alfentanil 6 μg/kg was given at anesthesia induction in all the patients, and then lidocaine 2 mg/kg was intravenously injected in the patients in group L. Modified Dixon′s up-and-down method was used for the study. Remimazolam was intravenously injected at a dose of 0.18 mg/kg in the first patient, and the gastroscope was placed when the eyelash reflex disappeared and the modified observational alertness/sedation assessment score ≤3. Gastroscope insertion response was defined as swallowing, bucking, body movement and other responses affecting the quality of examination during the gastroscope insertion. The dose of remimazolam was increased/decreased by 0.02 mg/kg in the next patient if the gastroscope response was positive or negative, and the process was repeated until 9 turning points occurred. The median effective dose (ED 50) and 95% confidence interval ( CI) of remimazolam were calculated by probit method. Results:The ED 50 (95% CI) of remidazolam in inhibiting responses to gastroscope insertion in elderly patients when combined with alfentanil was 0.158 (0.133-0.183) mg/kg in group C. The ED 50 (95% CI) of remidazolam in inhibiting responses to gastroscope insertion in elderly patients when combined with fentanyl was 0.139 (0.127-0.151) mg/kg in group L. The ED 50 was significantly lower in group L than in group C ( P=0.003). Conclusions:Intravenous lidocaine in combination with alfentanil increases the efficacy of remimazolam for painless gastroscopy in elderly patients.