Oral Ondansetron to Reduce Vomiting in Children Receiving Intranasal Fentanyl and Inhaled Nitrous Oxide for Procedural Sedation and Analgesia: A Randomized Controlled Trial

Intranasal fentanyl and inhaled nitrous oxide are increasingly combined to provide procedural sedation and analgesia in the pediatric emergency setting. This regimen is attractive because of its nonparenteral administration, but is associated with a higher incidence of vomiting than nitrous oxide alone. We seek to assess whether prophylactic oral ondansetron use could reduce the incidence of vomiting associated with intranasal fentanyl and nitrous oxide for procedural sedation compared with placebo. This was a double-blind, randomized controlled trial of oral ondansetron versus placebo conducted at a single tertiary care pediatric emergency department. Children aged 3 to 18 years with planned sedation with intranasal fentanyl and nitrous oxide were randomized to receive oral ondansetron or placebo 30 to 60 minutes before nitrous oxide administration. The primary outcome was early vomiting associated with procedural sedation, defined as occurring during or up to 1 hour after nitrous oxide administration. Secondary outcomes included vomiting 1 to 24 hours after procedural sedation, procedural sedation duration, adverse events, and quality of sedation across the 2 groups. We recruited 442 participants and 436 were included for analysis. There was no significant difference in the primary outcome, early vomiting associated with procedural sedation, between the groups: ondansetron 12% versus placebo 16%, with a difference in proportions of –4.6% (95% confidence interval –11% to 2.0%; P=.18). Most sedations were reported as optimal by treating clinicians (91%). Only 2 minor adverse events occurred, both in the placebo group. Oral ondansetron does not significantly reduce vomiting during or shortly after procedural sedation with combined intranasal fentanyl and inhaled nitrous oxide.