Ketamine is a versatile pharmacologic agent whose unique receptor interactions explain its broad applicability in emergency medicine. Its primary mechanism of action is non-competitive antagonism of N-methyl-D-aspartate (NMDA) receptors, which underlies its dissociative, anesthetic, and analgesic properties. By reducing excitatory neurotransmission and limiting glutamatergic activity, ketamine provides effective sedation while helping prevent neurotoxicity. Additional interactions with opioid, monoaminergic, and cholinergic systems contribute to its analgesic and psychotropic effects, reinforcing its neuroprotective and antidepressant potential. Ketamine is rapidly absorbed, crosses the blood-brain barrier efficiently, and is metabolized in the liver by cytochrome P450 enzymes CYP3A4 and CYP2B6 into active metabolites such as hydroxynorketamine. Its short half-life and multiple routes of administration, including IV, intramuscular (IM), and intranasal, allow for flexible use in different clinical contexts. In the ED, ketamine is used for procedural sedation, fracture and dislocation reduction, wound repair, and trauma management. Its dissociative properties ensure adequate analgesia and amnesia while preserving airway reflexes, reducing the need for additional anesthetic agents. It is particularly valuable in pediatric patients, providing effective sedation and pain control with minimal adverse effects. In cases of trauma, burns, or shock, the sympathomimetic activity of ketamine helps maintain cardiovascular tone and perfusion, offering an advantage over opioids, which may cause hypotension or respiratory depression. Adverse reactions are uncommon but may include laryngospasm, hypertension, tachycardia, or psychological emergence phenomena such as agitation or hallucinations. Coadministration of benzodiazepines can mitigate these effects and improve patient comfort during recovery. Standardized dosing protocols, typically 0.15-0.30 mg/kg IV for analgesia and 2-5 mg/kg IM for sedation, ensure both efficacy and safety. Comparative studies indicate that ketamine maintains hemodynamic stability better than etomidate and has a more favorable respiratory profile compared with benzodiazepine-opioid combinations. Overall, ketamine remains a cornerstone agent for emergency procedural sedation due to its rapid onset, reliability, and adaptability across a wide range of patient populations.
Montoya et al. (Tue,) studied this question.