Expected Action & Physiology

Ketamine is a nonbarbiturate phencyclidine derivative that acts as an NMDA receptor antagonist, blocking glutamate to selectively interrupt thalamoneocortical pathways while stimulating the limbic system. This induces "dissociative anesthesia" where the patient is unresponsive to pain, but eyes remain open with intact corneal, light, and airway reflexes.

It stimulates the sympathetic system, causing bronchodilation (ideal for asthma/bronchospasm), tachycardia, and hypertension. Direct negative inotropic effects can predominate in critically ill or catecholamine-depleted patients, causing hypotension. Cholinergic activation causes hypersalivation and elevated ICP/IOP. ...