Xinyuan Shi,1,* Fuxia Yi,2,3,* Hongyi Xiao,2,3 Shiyu Yu,1 Xiaohan Sun,1 Yaxin Wei,1 Fangli Yue,2,3 Fanceng Ji2,3 

1School of Anaesthesiology,Shandong Second Medical University, Weifang, People’s Republic of China; 2Department of Anaesthesiology,Weifang People’s Hospital, Weifang, People’s Republic of China; 3First Affiliated Hospital of Shandong Second Medical University, Weifang, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Fanceng Ji, Department of Anesthesiology, Weifang People’s Hospital, No. 151 Guangwen Street, Kuiwen District, Weifang, 261041, People’s Republic of China, Tel +86-13563698838, Email jifanceng@163.com

Purpose: To investigate the effects of low-dose alfentanil on the 50% effective dose (ED50)/95% effective dose (ED95) of remimazolam for successful loss of consciousness during general anesthesia in pediatric patients.
Patients and Methods: Fifty-two pediatric patients (aged 3– 12, ASA I–II) scheduled for elective surgery were divided into two groups: Group A (n=24;alfentanil 5 μg kg− 1 + remimazolam 0.1 mg kg− 1) and Group C (n=28;saline + remimazolam 0.15 mg kg− 1). The MOAA/S scale was employed for assessment. To calculate the ED50, ED95 of remimazolam for inducing loss of consciousness in pediatric patients undergoing general anesthesia. Record the monitored values (MAP, HR, SpO2) at different time points and the incidence of injection pain, hiccups, spontaneous movements, hypotension, bradycardia, respiratory depression, and overall adverse events.
Results: In Group A, the ED50 of remimazolam for loss of consciousness in pediatric patients was 0.212 mg kg− 1 (95% CI: 0.182 – 0.242 mg kg− 1), significantly lower than that in Group C (0.340 mg kg− 1, 95% CI: 0.295– 0.388 mg kg− 1, P < 0.001). Similarly, the ED95 in Group A was 0.265 mg kg− 1 (95% CI: 0.237– 0.413 mg kg− 1), significantly lower than that in Group C (0.434 mg kg− 1, 95% CI: 0.387– 0.737 mg kg− 1, P < 0.001). The overall incidence of adverse reactions was 8.3% in Group A, significantly lower than the 39.3% in Group C (P = 0.012). Compared with baseline values at T0, the MAP of pediatric patients in both groups decreased at T2 (P< 0.05), but the reduction remained within 20% of the baseline values.
Conclusion: Low-dose alfentanil (5 μg kg− 1) significantly reduces the ED50 and ED95 of remimazolam for successful loss of consciousness during paediatric general anaesthesia induction and decreases the incidence of adverse reactions during remimazolam induced sedation.

Keywords: alfentanil, effective dose, general anaesthesia, paediatric, remimazolam, sedation