Associations with early vomiting when using intranasal fentanyl and nitrous oxide for procedural sedation in children: A secondary analysis of a randomised controlled trial.

Objective: Intranasal (IN) fentanyl and nitrous oxide (NO) can be combined to provide procedural sedation and analgesia to children. This combination is advantageous because of rapid onset of action and non-parenteral administration, but is associated with increased vomiting. We sought to describe the associations of demographic and procedural factors with early vomiting when using this combination in children.

Methods: This was a planned secondary analysis of a randomised controlled trial comparing the effect of oral ondansetron versus placebo at a single paediatric hospital. Children aged 3 to <18 years with planned procedural sedation with IN fentanyl and NO were randomised to receive oral ondansetron or placebo prior to NO administration. Vomiting was defined as early if occurring during or up to 1 h after NO delivery. We assessed the relationship between early vomiting, demographic and procedural characteristics.

Results: Participants were recruited between October 2016 and January 2019 and 62 out of 436 (14%) had early vomiting. The risk of early vomiting was 30% higher with higher total dose of fentanyl, risk ratio = 1.3 (95% confidence interval = 1.004-1.59). There was little evidence of a relationship between the occurrence of early vomiting and sex, age, weight, type of procedure, fasting duration, time between fentanyl administration and start of procedure, and procedure duration.

Conclusion: We found that higher doses of IN fentanyl were associated with higher risk of early vomiting when administered with NO in children. Other factors did not appear to be associated with vomiting.