Intravenous Sub-dissociative Dose Ketamine Injection Versus Infusion for Analgesia in the Emergency Department

Objective: The purpose of this randomized, controlled, double-blind trial is to evaluate if sub-dissociated dose ketamine given as an infusion versus an intravenous (IV) push over 1 minute has fewer and/or less severe adverse drug reactions and provides equivalent analgesia for patients with moderate to severe pain in the emergency department (ED).

Study design: Prospective, randomized, controlled, double-blind trial

Participants: Research assistants will recruit patients ≥18 years old with moderate to severe pain (NRS≥5) and an anticipated stay in the emergency department ≥1 hour. A sample size calculation was performed based on prior data which suggests that 60% of IV push arm and 20 % of infusion arm will have adverse drug reactions. investigators assume an alpha of 0.05 and a power of 0.8, which results in 56 patients needing to be enrolled.

Intervention: After a trained research assistant obtains written informed consent, pharmacists will randomize the participants to the IV push or IV infusion arm of the study. All patients will be placed on a cardiac monitor. All patients will receive and IV push over 1 minute and a 100 mL normal saline minibag over 15 minutes.

In the IV push arm, pharmacists will provide to the nurse ketamine 0.3 mg/kg in a 10 mL syringe and a 100 mL normal saline minibag. The nurse will start the minibag of normal saline and then administer the IV push of ketamine over 1 minute.

In the IV infusion arm, pharmacists will provide to the nurse ketamine 0.3 mg/kg in a 100 mL normal saline minibag and a 10 mL syringe of normal saline. The nurse will start the minibag of normal saline and then administer the IV push over 1 minute.

Data collection: The trained research assistant will collect data on the patients' pain scores, adverse drug reactions (presence, severity, and how bothersome they are), and vital signs.

Statistical analysis: Investigators will perform descriptive statistics, compare the proportion of patients with side effects, compare the severity of the side effects scores, and compare how bothersome the side effects.

Inclusion criteria

• Pain NRS ≥5
• Anticipated stay in ED ≥1 hour

Exclusion criteria

• Pregnant or breast feeding
• Vital sign abnormalities (SBP <90, SBP > 180, HR < 50, HR > 150, RR <10, RR > 30, weight <45 kg, weight > 115 kg)
• Arrhythmias
• Altered mental status (active psychosis/delirium)
• Administration of opioid pain medication in previous 1 hour
• history of acute head or ocular trauma
• presence of known intracranial mass or vascular lesion