Advanced Pharmacology · Topic 5 of 13

RSI Drugs & Neuromuscular Blockers

Critical care · rapid sequence intubation drugs

RSI Drugs & Neuromuscular Blockers

Pair an induction agent with a paralytic: succinylcholine 1.5 mg/kg unless hyperkalemia risk, otherwise rocuronium 1.2 mg/kg — reversible with sugammadex 16 mg/kg.

Key numbers

Succinylcholine 1.5 mg/kg: fastest, shortest1.5 mg/kg

Rocuronium 1.2 mg/kg for RSI1.2 mg/kg

Sugammadex 16 mg/kg reverses rocuronium immediately16 mg/kg

01 · GiveSuccinylcholine 1.5 mg/kg: fastest, shortest

Succinylcholine 1.5 mg/kg IV, a depolarizing blocker, has the fastest onset (30–60 seconds) and shortest duration (3–5 minutes); it transiently raises potassium by about 0.5–1.0 mEq/L.

02 · GiveRocuronium 1.2 mg/kg for RSI

Rocuronium 1.2 mg/kg IV (label RSI range 0.6–1.2 mg/kg) gives good intubating conditions in under 2 minutes and lasts over 30 minutes; SCCM accepts rocuronium or succinylcholine when succinylcholine is not contraindicated.

03 · AvoidNo succinylcholine after burns, crush or denervation

Avoid succinylcholine with hyperkalemia or AKI, beyond 1–2 days after major burns or crush injury, with denervation (spinal cord or upper motor neuron injury), myopathy, prolonged ICU stay, or malignant hyperthermia susceptibility.

Diagnosis & monitoring

Work-up

Paralysis infusion: sedation, eye care, train-of-fourDuring continuous neuromuscular blockade give deep sedation and analgesia, lubricate and close the eyes (strong recommendation), and titrate with a peripheral nerve stimulator (train-of-four) to avoid prolonged paralysis.

Do right now

In this order

First moves

Always pair induction agent and paralytic

→

Etomidate 0.3 mg/kg: hemodynamically stable induction

→

No succinylcholine after burns, crush or denervation

→

Rocuronium 1.2 mg/kg for RSI1.2 mg/kg

→

Start sedation right after intubation

Why each step

Always pair induction agent and paralyticFor RSI, give a neuromuscular blocker whenever a sedative-hypnotic induction agent is used (SCCM strong recommendation), and never give a neuromuscular blocker without a sedative-hypnotic.

Etomidate 0.3 mg/kg: hemodynamically stable inductionEtomidate 0.3 mg/kg IV is a common RSI induction agent; it transiently suppresses cortisol synthesis, but SCCM finds no outcome difference versus other agents and suggests against routine steroids after it.

No succinylcholine after burns, crush or denervationAvoid succinylcholine with hyperkalemia or AKI, beyond 1–2 days after major burns or crush injury, with denervation (spinal cord or upper motor neuron injury), myopathy, prolonged ICU stay, or malignant hyperthermia susceptibility.

Rocuronium 1.2 mg/kg for RSIRocuronium 1.2 mg/kg IV (label RSI range 0.6–1.2 mg/kg) gives good intubating conditions in under 2 minutes and lasts over 30 minutes; SCCM accepts rocuronium or succinylcholine when succinylcholine is not contraindicated.

Start sedation right after intubationHave post-intubation sedation and analgesia ready and start it immediately — especially after rocuronium, whose paralysis lasts more than 30 minutes; then aim for light sedation with propofol or dexmedetomidine.

Management

Orders

Sugammadex 16 mg/kg reverses rocuronium immediately must knowSugammadex 16 mg/kg (actual body weight) can reverse rocuronium 1.2 mg/kg as early as about 3 minutes after it, faster than recovery from succinylcholine — but in can't-intubate-can't-oxygenate, prioritize oxygenation, including a surgical airway.

Ketamine 1–2 mg/kg: no survival advantageKetamine 1–2 mg/kg IV is a cardiostimulatory dissociative agent; in the 2026 RSI trial it did not lower 28-day mortality versus etomidate (28.1% vs 29.1%) and caused more cardiovascular collapse (22.1% vs 17.0%).

Propofol induction causes hypotensionPropofol 1.5–3 mg/kg IV induces rapidly but depresses the circulation and causes hypotension — reduce or avoid it in shock.

Fentanyl blunts the intubation pressor responseFentanyl blunts the hypertensive, tachycardic response to laryngoscopy; reduce the induction-agent dose when combining them, and beware chest-wall rigidity at high doses.

Obesity: succinylcholine on total weightIn obesity dose succinylcholine on total body weight (plasma cholinesterase activity rises) and rocuronium on lean body weight — total-weight rocuronium does not speed onset but markedly prolongs paralysis.

Cisatracurium: organ-independent Hofmann eliminationCisatracurium is cleared by Hofmann elimination independent of the kidneys and liver, making it one of the most commonly used blockers for ICU infusions (for example, early severe ARDS).

Red flags & don'ts

Avoid harm

Succinylcholine triggers malignant hyperthermia complicationSuccinylcholine can trigger malignant hyperthermia (treated with IV dantrolene; see Malignant Hyperthermia) and is contraindicated with known or suspected genetic susceptibility.

Succinylcholine or rocuronium?

Commonly confused

Class	Depolarizing
RSI dose	1.5 mg/kg IV
Onset	30–60 seconds
Duration	3–5 minutes
Hyperkalemia risk	Yes — avoid after burns, crush, denervation
Reversal	None — wait for recovery

More detail

Reference

Show 7 reference facts

Succinylcholine can cause bradycardia, especially after a second dose (atropine pretreatment reduces it), raises intraocular and intracranial pressure, and causes prolonged paralysis with reduced plasma cholinesterase activity.

Routine sugammadex doses are 2 mg/kg when the train-of-four count has recovered to 2 and 4 mg/kg for deep block (1–2 post-tetanic counts); neostigmine only works on shallow block (train-of-four count over 3).

Sugammadex can cause anaphylaxis and marked bradycardia, occasionally progressing to cardiac arrest, within minutes of administration.

Do not count on succinylcholine wearing off in time to rescue a failed airway: in obesity its fasciculations raise oxygen consumption and shorten safe apnea time.

SCCM found insufficient evidence to favor peri-intubation vasopressors over IV fluids for hypotensive patients undergoing RSI.

Succinylcholine carries a boxed warning for hyperkalemic rhabdomyolysis and cardiac arrest in apparently healthy children with undiagnosed myopathy; it is reserved for emergency intubation in pediatric patients.

Rocuronium is cleared mainly by the liver (about 90%); vecuronium and pancuronium have active metabolites linked to ICU-acquired weakness.

Pearl

Before succinylcholine, ask what has happened to the muscle — burns, crush, denervation or a long ICU stay mean rocuronium.

Sources · Merck Manual Professional — Medications to Aid Intubation (Jun 2026) · Acquisto NM et al. SCCM Clinical Practice Guidelines for Rapid Sequence Intubation in the Critically Ill Adult Patient. Crit Care Med 2023;51:1411–1430 — SCCM guideline page · Casey JD et al. Ketamine or Etomidate for Tracheal Intubation of Critically Ill Adults (RSI trial). N Engl J Med 2026;394:1608–1620 · Quelicin (succinylcholine chloride) prescribing information — DailyMed (contraindications; §5.4 hyperkalemia; §5.5 malignant hyperthermia; §5.6 bradycardia) · Rocuronium bromide injection prescribing information — DailyMed (§2.3 rapid sequence intubation) · Bridion (sugammadex) prescribing information — DailyMed · Renew JR et al. Neuromuscular blockade management in the critically ill patient. J Intensive Care 2020;8:37 · Nightingale CE et al. Peri-operative management of the obese surgical patient 2015 (AAGBI / SOBA). Anaesthesia 2015;70:859–876 · Ryanodex (dantrolene sodium) injectable suspension prescribing information — DailyMed · Starter sheet built from the verified AGACNP fact map (facts reviewed 2026-10-15).