Multi-center RCT of IV Ketamine Efficacy and Safety in Chronic Daily Headaches

Bolus of IV Ketamine 1 mg.kg-1 (= 0.1 ml.kg-1) followed by Infusion of Ketamine 1 mg.kg-1.hour-1 (= 0.5 mL.kg-1.hour-1) for 6 hours. All patients will receive IV midazolam 0.04 mg.kg-1 (maximum 3 mg) and subsequently 0.01-0.02 mg.kg-1 every hour to keep participants in a sedated but arousable state (Ramsay Sedation Scale score 3 or 4) to blind the participants and assessors to group allocation. Ondansetron 8 mg and 8 mg of dexamethasone will be administered to prevent nausea, 5000 units of heparin will be given subcutaneously to prevent thrombo-embolic events.

Bolus of IV Saline 0.9% of 0.1 ml.kg-1 followed by Infusion of Saline 0.9% of 0.5 mL.kg-1.hour-1 for 6 hours. All patients will receive IV midazolam 0.04 mg.kg-1 (maximum 3 mg) and subsequently 0.01-0.02 mg.kg-1 every hour to keep participants in a sedated but arousable state (Ramsay Sedation Scale score 3 or 4) to blind the participants and assessors to group allocation. Ondansetron 8 mg and 8 mg of dexamethasone will be administered to prevent nausea, 5000 units of heparin will be given subcutaneously to prevent thrombo-embolic events.