Median effective dose of intranasal dexmedetomidine for satisfactory mask induction in children undergoing examination under anaesthesia for retinoblastoma - A prospective up and down sequential allocation study.

Background and aims: Inhalational technique is used to induce anaesthesia in children without intravenous access. We aimed to determine the median effective dose (ED50) of intranasal dexmedetomidine to ensure satisfactory mask acceptance during inhalation induction in children with retinoblastoma undergoing examination under anaesthesia.

Methods: A prospective sequential allocation study was conducted in children aged 1-60 months divided into Group A (1-18 months) and Group B (18-60 months). Children were administered dexmedetomidine intranasally as premedication. Sedation was assessed using the modified Observer Assessment of Alertness and Sedation Scale until induction. Successful mask acceptance was defined as a cooperative or asleep child during inhalational induction. The starting dose of dexmedetomidine was 1 µg/kg. The next dose varied by 0.2 µg/kg depending on the outcome of this case. According to the Dixon up-and-down method, the mean of midpoints of the failure-success sequence was calculated to obtain the ED50 values.

Results: The ED50 of intranasal dexmedetomidine for satisfactory mask acceptance was 0.7 µg/kg (95% confidence interval [CI]: 0.54-0.86) in Group A (n = 23) and 0.96 µg/kg (95% CI: 0.83-1.08) in Group B (n = 25) (P = 0.020). The mean (standard deviation) duration of anaesthesia was 33.5 (14.9) minutes in group A versus 23.5 (8.48) minutes in Group B (P = 0.007).

Conclusion: ED50 was lower in children younger than 18 months than in older children. There was no difference in the time to discharge from the post-anaesthesia care unit despite the procedure being longer in smaller children.