Intranasal (IN) delivery of analgesic agents provides rapid and convenient drug administration without the need for needles. In children, the placement of an intravenous line often increases anxiety and pain, requires nursing time, and can be very difficult to achieve, so the IN route is particularly advantageous. IN delivery of fentanyl has become increasingly more common in pain management for children in many settings, including pre-hospital and emergency department (ED) settings. Over the past decade, many studies have demonstrated that intranasal fentanyl is as effective as intravenous morphine to treat acute moderate to severe pain. Intranasal fentanyl has become standard of care in some pediatric EDs with the advantage of avoiding intravenous line placement. However, adverse effects attributed to IN fentanyl are similar to those of other opioid analgesics: hypotension, sedation, and occasionally respiratory depression. Ketamine is a noncompetitive N-methyl D-aspartate (NMDA) receptor antagonist that blocks the release of the excitatory neurotransmitter glutamate and provides anesthesia, amnesia, and analgesia by decreasing central sensitization and "wind-up" phenomenon. Due to its high lipid solubility, ketamine rapidly crosses the blood-brain barrier, provides rapid onset of action (peak concentration at 1 minute after intravenous push) and rapid recovery to baseline (duration of action 5-15 minutes after intravenous push). At sub-dissociative doses, either used as an adjunct to opioid analgesics or as a solo agent, ketamine provides effective analgesia while preserving airway patency, ventilation, and cardiovascular stability.

Ketamine has been less studied for pain management, however it has been safely used via different routes of administration in children. Studies dating back to 1990's use ketamine at doses as high as 6 mg/kg intranasally in children for pre-medication prior to surgery or for sedation with little or no reported adverse effects. A hospital in Australia is currently conducting a clinical trial comparing IN fentanyl 1.5 ug/kg to IN ketamine 1mg/kg for the treatment of pain caused by isolated musculoskeletal injury. The intention of our study is similar to this, however the investigators will not limit the patients to those with only musculoskeletal pain and a more simplified pain scale will be used.

To assess pain, the investigators will use the standard pain scale that is currently used in our Pediatric ED in order to minimize the need to re-train any of our staff with a different pain scale. The scale incorporates the Numerical rating scale (0-10 scale; NRS) and the Wong-Baker faces pain scale (6 faces corresponding to 0,2,4,6,8,10; WBS). While prior studies have used different pain scales, primarily the visual analog scale (VAS), the scales that the investigator currently use have been validated in children in 2009.