Updated July 2026 · 9 min read
Part of the ICU Pharmacology Hub — browse every related guide in one place.
Ketamine has gone from a niche anesthetic to one of the most versatile drugs in critical care — an induction agent, an analgesic, a sedative, and a bronchodilator all at once. Here is the practical, protocol-aware picture every ICU nurse and CRNA student should carry.
Ketamine primarily blocks the NMDA glutamate receptor, producing a "dissociative" state — the patient appears awake or cataleptic but is disconnected from sensory input, with profound analgesia and amnesia. Unlike propofol or benzodiazepines, it stimulates the sympathetic nervous system, which is why heart rate and blood pressure typically rise rather than fall. It also relaxes bronchial smooth muscle, giving it a genuine bronchodilator effect.
Ketamine is dose-dependent: tiny doses treat pain, larger doses induce anesthesia. Common ICU/ED ranges (always per protocol):
| Use | Typical dose |
|---|---|
| Sub-dissociative analgesia (bolus) | ~0.1–0.3 mg/kg IV over 10–15 min |
| Analgesic infusion | ~0.1–0.5 mg/kg/hr |
| RSI induction | ~1–2 mg/kg IV push |
| Sedation infusion (adjunct) | ~0.5–2 mg/kg/hr (unit-specific) |
| IM (no IV access) | ~4 mg/kg IM |
The low-dose analgesic use is where ketamine has exploded in popularity: a ketamine infusion spares opioids, helps opioid-tolerant and chronic-pain patients, and avoids the respiratory depression that limits fentanyl. Many units now run sub-dissociative ketamine for exactly this reason.
Emergence reactions. On waking, patients can experience vivid dreams, hallucinations, agitation, or dysphoria. Lower doses, a calm environment, and a small benzodiazepine (if ordered) reduce this. It is more prominent in adults than young children.
Hypertension and tachycardia. The sympathetic surge raises myocardial oxygen demand — use caution in active coronary ischemia, aortic dissection, or severe uncontrolled hypertension.
Hypersalivation. Ketamine increases secretions, which can complicate airway management; antisialagogues are sometimes used.
Laryngospasm. Rare but real, particularly with rapid pushes or in children — have airway equipment ready.
ICP/IOP. Older teaching held ketamine raised intracranial pressure and was contraindicated in head injury; current evidence is more nuanced and it is often used in trauma, but follow your institution's stance.
For anyone on the CRNA path, ketamine is foundational anesthesia pharmacology. It is a workhorse induction agent for hemodynamically unstable patients, a multimodal analgesia component that reduces intraoperative and postoperative opioid needs, and a bronchodilator for reactive airways. Understanding its dissociative mechanism, its sympathomimetic profile, and its emergence phenomena at the ICU bedside is precisely the knowledge you will apply in the OR — just at anesthetic doses.
Ketamine is the versatile one: analgesia without respiratory depression, induction without hypotension, and bronchodilation for the crashing asthmatic. Respect the emergence reactions, watch the sympathetic surge in cardiac patients, manage the secretions, and never drop your airway vigilance. Master it at the bedside and you carry it straight into anesthesia practice.
This article is general educational information for licensed clinicians and students, not medical advice or a substitute for your institution's protocols, pharmacy guidance, or a provider's orders. Always follow facility policy and verify every dose independently.
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