A study performed by Evans et al. demonstrated that the pain and memory of the procedure between children receiving either nitrous oxide versus children receiving intramuscular meperidine in combination with promethazine for fracture reduction was similar, but there was increased satisfaction and decreased length of stay in the nitrous oxide group. Seith et al. demonstrated that the addition of intranasal fentanyl to nitrous oxide in children resulted in deeper levels of sedation when compared to nitrous oxide alone; however, there were no serious adverse events.