Protocol for a double blind, randomised placebo-controlled trial using ondansetron to reduce vomiting in children receiving intranasal fentanyl and inhaled nitrous oxide for procedural sedation in the emergency department (the FON trial)

Introduction: Intranasal fentanyl and nitrous oxide (N2O) can be combined to create a non-parenteral procedural sedation regimen for children in the paediatric emergency department. This combination of intranasal fentanyl and N2O provides effective pain relief for more painful procedures, but is associated with a higher incidence of vomiting than N2O alone. Our aim is to assess whether ondansetron used preventatively reduces the incidence of vomiting associated with intranasal fentanyl and N2O for procedural sedation compared with placebo. Methods and analysis: This study is a double blind, randomised placebo-controlled superiority trial. This is a single-centre trial of 442 children aged 3-18 years presenting to a tertiary care Paediatric Emergency Department at the Royal Children's Hospital (RCH), Melbourne, Australia, requiring procedural sedation with intranasal fentanyl and N2O. After written consent, eligible participants are randomised to receive ondansetron or placebo along with intranasal fentanyl, 30-60 min prior to N2O administration. The primary outcome is vomiting during or up to 1 hour after procedural sedation. Secondary outcomes include: number of vomits and retching during procedural sedation, vomiting 1-24 hours after procedural sedation, procedural sedation duration and associated adverse events, procedure abandonment, parental satisfaction and the value parents place on the prevention of vomiting. This trial will allow refinement of a non-parenteral sedation regimen for children requiring painful procedures. Ethics and dissemination: This study has ethics approval at the RCH, Melbourne, protocol number 36174. The results from this trial will be submitted to conferences and published in a peer-reviewed journal. Trial registration number: Australian New Zealand Clinical Trials Registry (ACTRN12616001213437)