Updated July 2026 · 9 min read

Etomidate vs Ketamine for RSI 2026 — The Two Induction Agents

Part of the ICU Pharmacology Hub — browse every related guide in one place.

When a patient in the ICU needs an emergent airway, the induction agent chosen for rapid sequence intubation (RSI) is one of the highest-stakes decisions in the room — it decides how the blood pressure behaves in the seconds after the patient goes unconscious. In critically ill adults, that choice comes down most often to etomidate or ketamine. Knowing how each behaves lets you anticipate what the pressure will do and have the right rescue ready.

What each drug is

Etomidate is an imidazole hypnotic that works at GABA receptors to produce rapid unconsciousness with minimal effect on heart rate, blood pressure, or cardiac output. That hemodynamic neutrality is exactly why it became a default RSI induction agent for unstable patients. Ketamine is an NMDA-receptor antagonist that produces a dissociative anesthesia — the patient is disconnected from the environment — while preserving respiratory drive and airway reflexes better than most agents, and while stimulating the sympathetic nervous system to raise heart rate and blood pressure.

Hemodynamics: the deciding factor

In a hypotensive or shocked patient, the pressure response to induction is everything. Etomidate is close to neutral — it won't add a pressor push, but it usually won't drop the pressure either. Ketamine actively raises the pressure in most patients by releasing endogenous catecholamines, which is why it is often favored in hemorrhagic or septic shock. The important caveat: in a patient who is already maximally sympathetically driven and catecholamine-depleted (long, decompensated shock), ketamine can lose that supportive effect and even reveal direct myocardial depression, dropping the pressure instead. In that specific patient, ketamine is not the free pass it looks like.

The etomidate adrenal-suppression debate

Etomidate's Achilles' heel is that even a single induction dose transiently inhibits 11-beta-hydroxylase, the enzyme adrenal glands use to make cortisol, blunting the stress-cortisol response for hours. In sepsis — where the body leans hard on cortisol — this raised a long-running question about whether etomidate worsens outcomes. The evidence has stayed genuinely mixed: many clinicians still use a single dose comfortably, while others avoid it in septic shock on principle and reach for ketamine.

Ketamine's cautions

Ketamine's sympathetic stimulation is usually a gift, but it can be a liability: in a patient whose survival depends on not increasing myocardial oxygen demand — severe coronary disease, aortic dissection, or a heart already running on maximal endogenous drive — the tachycardia and pressure rise can hurt. Older teaching that ketamine dangerously raises intracranial pressure has been largely walked back, and it is now commonly used in head-injured patients, but individual institutions vary. Emergence phenomena (vivid, sometimes distressing dissociation on waking) are more relevant to procedural sedation than to the intubated, sedated ICU patient. And as with etomidate, ketamine does not paralyze — the paralytic runs alongside it.

How the team chooses — and what you prepare

There is no universal winner; the choice is patient-specific. Broadly, ketamine is attractive in undifferentiated shock, hemorrhage, and bronchospastic patients (it bronchodilates), while etomidate is favored when clinicians want the cleanest possible hemodynamics and are unconcerned about, or actively managing, the adrenal question — and it may be preferred in the fixed-cardiac-output or tachycardia-intolerant patient where ketamine's sympathetic surge is unwanted.

Related: Rocuronium vs vecuronium · Cisatracurium vs succinylcholine · Precedex vs propofol · Hydrocortisone in septic shock

Educational content for licensed clinicians. Airway management and RSI drug selection are performed by credentialed providers per institutional protocol. Not medical advice.