It is hypothesized that the addition of IN ketamine to usual care with nitrous oxide inhalation for adults experiencing moderate to severe intensity acute pain in the pre-hospital setting will result in a greater proportion of patients experiencing a 2-point or more reduction in verbal numerical rating scale (VNRS) pain score within 30 minutes, as well as improved patient-reported comfort, reduced nitrous oxide requirements, and improved patient and provider satisfaction compared to usual care alone.