Low Dose Ketamine (LDK) Versus Morphine for Acute Pain Control in the Emergency Department

Phase 1 is a randomized, controlled, double-blinded study comparing the use of low-dose ketamine (LDK) to morphine for acute pain control in emergency department patients. A convenience sample of subjects will be enrolled from a population of patients aged 18-50 who present to the Brooke Army Medical Center Emergency Department with acute abdominal pain, flank/lumbar back pain and/or pain to the extremities. To take part in the study, a need for opioid analgesia must be indicated by the treating physician in addition to the patient meeting all other study criteria.

The patient will then be randomized into one of the two treatment arms. Prior to receiving either the study medication (ketamine) or the active control (morphine) the patient will be asked to rate their pain on a numeric rating scale (NRS) with 0 being no pain and 10 being the worst pain possible. Their baseline vital signs (blood pressure, heart rate, respiratory rate and oxygen saturation) will also be documented. These vital signs and the NRS will be reassessed at 5, 10 and 20 minutes post medication dosage. At 20 minutes they will also document a Richmond Agitation Sedation Scale (RASS) score and will ask the patient if they require additional pain medication. If the patient denies the need for a second dose of medication they will continue to be re-assessed every 20 minutes (vital signs, NRS, and RASS) until either inpatient admission, discharge home, transfer to the operating room or until a total of 120 minutes after initial dosing.

If at any time during the study the patient requires a second dose of pain medication, following the administration of the med, they will be assessed for vital signs at 5,10 and 20 minutes after the dose. At 20 minutes, a RASS score and NRS score will also be documented. They will then be re-assessed every 20 minutes (vital signs, NRS, and RASS) until either inpatient admission, discharge home, transfer to the operating room or until a total of 120 minutes after initial dosing.

If they require a third dose of pain medication at any time during the study, this is considered a treatment failure and the treating physician will be contacted to provide any further pain control.

The second phase of the study will be observational. An anonymous satisfaction survey will be provided to the treating nurse, physician or physicians assistant (PA) of the patients recruited from part one of the study. The purpose of conducting the survey is so that an observation point of view can be added to the data to provide a measure of how well the patient's pain was controlled.

Inclusion criteria

• Patients age 18-59 who present to the Brooke Army Medical Center Emergency Department with acute (less than 10 days) abdominal pain, flank/lumbar back pain and or/pain to the extremities, and of sufficient severity in the judgement of the ED treating physician or PA to warrant use of intravenous opioids

Exclusion criteria

• Poor vital sign stability hypoxia: Sats<95% hypotension: SBP<90 hypertension: SBP>180 heart rate: <50 or >120 respiratory rate: <10 or >30
• Altered mental status or intoxication
• Patient is unwilling to participate or provide informed consent
• History of chronic pain or pain syndrome with concurrent opioid medication use
• fibromyalgia
• Patient has received opioids and/or tramadol in the past 4 hours
• Prescription pain medication use (to exclude muscle relaxants, acetaminophen or NSAIDs including toradol) in the past 4 hours
• Allergy to morphine or ketamine
• Sole provider status
• Adverse reaction to morphine or ketamine in the past
• Patients, who in the opinion of the triage nurse, require immediate analgesic relief
• Patient is female of child-bearing age and unable to provide urine or serum for HCG analysis in triage
• Pregnancy or breast feeding
• Presence of oxygen dependent pulmonary disease, liver cirrhosis or Renal disease requiring dialysis. (as assessed by electronic chart review)
• Presence of Ischemic heart disease, heart failure or unstable dysrhythmias (as assessed by electronic chart review)
• Presence of intracranial mass or vascular lesion.
• Presence of psychosis or hallucinations
• Weight greater than 115kg or less than 45 kg
• History of acute ocular/head trauma
• History of increased intracranial pressure/hypertensive hydrocephalus
• Non-English speaking patients