The purpose of this study is to see whether intra-nasal (IN) Ketamine (50 mg / ml) solution (Sandoz; Drug Identification Number (DIN) 02246796) administered via mucosal atomization device (LMA MAD300 Nasal TM; Wolfe Tory Medical Inc., San Diego, CA), in addition to usual care with nitrous oxide inhalation, to pre-hospital patients being transported by British Columbia Emergency Health Services (BC EHS) Basic Life Support (BLS) paramedics with moderate to severe pain (pain > 5/10 on a validated numerical rating scale or NRS) will improve pain relative to usual care plus placebo.