Low Dose Ketamine Infusion for Analgesia in the Emergency Department to Reduce Side Effects

This will be an intent to treat prospective, double blind, double-dummy, randomized trial. Our primary objective is the reduction of side effects of sub dissociative dose ketamine given by slow intravenous (IV) infusion over 30 minutes vs. 15 minutes in the treatment of acute, severe pain in Emergency Department (ED) patients. The secondary objective will be to maintain adequate pain control (as defined by a Visual Analog Scale (VAS) score of ≤ 5cm) at 30 minutes for both groups.

Inclusion criteria: * Patients aged 18 or older * Primary complaint of acute moderate to severe pain on VAS/ numeric pain scale (a score of ≥5cm which corresponds to 50mm). * Pain described as abdominal, flank, back, musculoskeletal, or traumatic chest pain * Must be alert and oriented times three * Able to provide consent Exclusion criteria: * Pregnant * Breastfeeding * Altered mental status * Known or reported allergy, hypersensitivity or intolerance to ketamine * Unstable vital signs (systolic blood pressure \180mmHg, heart rate \150 beats per minute, and respiratory rate \30 breaths per minute) * History of unstable heart disease, such as arrhythmias, congestive heart failure, or coronary heart disease. * History of untreated or uncontrolled thyroid disease * Acute head or eye injury * Active or current use of alcohol or drugs * Known intracranial hypertension * Hepatic or renal insufficiency * Current active manic phase of bipolar disorder * Active delusions, hallucinations, or schizophrenia * Patients who have recent fentanyl use within 60 minutes or other analgesic use (opiates) within 4 hours of study enrollment (signing of consent) * Patients who have enrolled in the study during a previous ED encounter * Chronic use of opiates (i.e.: fentanyl patch, SR opiates)