Effect of preinfusion of low-dose alfentanil on the induction of anesthesia with remimazolam in gynecological day surgery: a prospective, double-blind, randomized controlled study

Abstract Purpose : Alfentanil has a synergistic sedative effect with benzodiazepines, and this study aimed to investigate the effect of preinfusion of low-dose alfentanil on the dose of remimazolam for loss of consciousness while observing the effect on hemodynamic changes and other adverse effects. Methods : Thirty-four gynecological day surgery patients were selected and randomly divided into the control group and the observation group; before anesthesia induction, both groups were given dexamethasone 5 mg, haloperidol 1 mg, and flurbiprofen ester 50 mg. Anesthesia induction: The control group was prefilled with 10 ml of saline, and remimazolam was pumped in rate of 6 mg/kg/h until consciousness disappeared; Micuronium chloride was injected slowly at 30 seconds, alfentanil 15 µg/kg was injected slowly at 30 seconds, and mechanical ventilation was carried out 2 minutes after placement of a laryngeal mask. In the observation group, first, 5µg/kg of alfentanil diluted to 10 ml was administered, remimazolam was pumped at rate of 6 mg/kg/h until consciousness disappeared, 0.2 mg/kg micuronium chloride was injected slowly for 30 seconds, 15 µg/kg alfentanil was injected slowly for 30 seconds, assisted ventilation was performed, a laryngeal mask was placed after 2 minutes, and mechanical ventilation was implemented. Anesthesia maintenance: remimazolam 1 mg/kg/h, alfentanil 40 µg/kg/h to maintain anesthesia, and micuronium chloride 0.05 mg/kg was given for more than 30 minutes of surgery; infusion of anesthetics was stopped at the end of surgery. The primary outcome was the dose of remimazolam for loss of consciousness; the secondary outcomes were the changes in hemodynamics during the induction period of anesthesia, and the incidence of adverse events such as hiccups and involuntary body movements during the induction period. Results: The dose of remimazolam for loss of consciousness in group A (13.14±2.51) mg was lower than that in group C (17.09±3.40) mg (p<0.05); the time to loss of consciousness in group A (123.81±21.08) s was lower than that in group C (156.80±30.67) s (p<0.05); the incidence rate of total adverse reactions in group A (12.5%) was lower than that in group C ( 46.6%); the heart rate of group A was slightly higher than that of group C (p=0.003), and there was no significant difference in MAP, SPO2 and BIS between the two groups (p>0.05). Conclusions : Preinfusion of a low dose of alfentanil significantly reduces the dose of remimazolam, causing loss of consciousness, speeds up induction, reduces the overall rate of adverse effects, and slightly increases heart rate.