Rapid sequence intubation

Oxygen: the bellows top (store left) and the SpO₂ needleSyringes: induction, paralytic, push-dose pressorLamps: train-of-four twitches; single lamp: patient awakePreoxygenation fills the store; the push is induction then paralytic back to back; apnoea starts as the block deepens and the store drains at the patient's oxygen use. The race is paralysis (TOF to 0/4, about 1 min) against the store running out. SpO₂ reads about 20 s late, the capnogram goes flat in apnoea and returns only with the tube in the trachea, and the awake lamp shows when the induction agent wears off before the paralytic.

Patient

Induction

Paralytic

Laryngoscopy

Nasal O₂ 15 L/min

The sequence: 7 Ps

When	Step	What you do
−10 min	Preparation	Plan A/B/C said out loud. SOAP-ME: suction, oxygen, airway kit (blade, bougie, tube one size down, SGA, cric kit), pharmacy drawn and labelled, monitoring, ETCO2 ready. Two IVs. Resuscitate first: fix hypotension, hypoxia, acidosis before the push.
−3 min	Preoxygenation	3 min tidal breathing or 8 vital-capacity breaths at FiO2 ~1.0 (NRB at flush rate, BVM with PEEP valve, or NIV). Head up 20–30°. Nasal cannula 15 L/min left on for apnoeic oxygenation. Goal: replace lung nitrogen with oxygen (ETO2 > 85–90%).
−3 min	Pretreatment (optional)	Fentanyl 2–3 mcg/kg if blunting the sympathetic surge matters (raised ICP, aortic dissection, ACS). Lidocaine has no outcome benefit. Atropine only for bradycardia risk (small children with sux).
0	Paralysis with induction	Induction agent IV push, flush, paralytic IV push immediately after. No titration.
0–45 s	Positioning, protection	Ear-to-sternal-notch, face parallel to ceiling. Cricoid pressure optional, release if it worsens the view. Gentle BVM (PEEP, low pressure) is fine if SpO2 is low or reserve is short.
45–60 s	Placement with proof	Start when jaw is flaccid (TOF 0). Waveform capnography for ≥5 breaths is the proof; colour change, misting and breath sounds are not. Tube ~21 cm at teeth (women), ~23 cm (men). Abort and bag if SpO2 falls to ~93% (the probe lags).
+1 min on	Post-intubation management	Analgesia first, then sedation, started within minutes (rocuronium outlasts every induction agent). Vent: VT 6–8 mL/kg ideal weight, PEEP 5, FiO2 1.0 then titrate. Expect hypotension from positive pressure: fluids, push-dose pressor ready. CXR, OG tube.

Induction agents (adult IV)

Drug	Dose	Onset / duration	Good for	Watch for
Etomidate	0.3 mg/kg (0.15–0.2 in shock)	30–60 s / 3–5 min	Haemodynamically neutral; trauma, cardiac disease	Myoclonus; single-dose adrenal suppression (debated in sepsis); no analgesia
Ketamine	1–2 mg/kg (0.5–1 in shock)	45–60 s / 10–20 min	Shock, asthma (bronchodilates), keeps airway reflexes and drive	Raises HR/BP, can drop BP in catecholamine-depleted shock; emergence reactions
Propofol	1–2.5 mg/kg (cut hard or avoid in shock)	15–45 s / 5–10 min	Status epilepticus, bronchospasm, stable patients	Vasodilation and hypotension; no analgesia
Midazolam	0.1–0.3 mg/kg	60–120 s / 15–30 min	Fallback only	Slow onset, hypotension; a poor RSI agent

Paralytics

Drug	Dose	Onset / duration	Notes
Succinylcholine	1.5 mg/kg total body weight (2 mg/kg infants; 4 mg/kg IM)	45–60 s / 6–10 min	Depolarising: fasciculations, then flaccid. K⁺ rises ~0.5 mEq/L. Do not use with hyperkalaemia, burns or crush >24–72 h old, denervation (stroke or spinal cord injury >72 h, ALS, MS), myopathies, malignant hyperthermia history, prolonged immobility. Bradycardia on repeat doses and in children. It wears off too late to save a desaturating patient.
Rocuronium	1.2 mg/kg (1.0–1.6; higher in shock)	45–60 s / 45–70 min	Non-depolarising, no K⁺ rise, no MH. Reversal: sugammadex 16 mg/kg for immediate reversal (2–4 mg/kg routine). Long block means sedation must follow.

Support drugs

Push-dose epinephrine 10 mcg/mL: 0.5–2 mL (5–20 mcg) every 2–5 min.
Push-dose phenylephrine 100 mcg/mL: 0.5–2 mL (50–200 mcg).
Post-intubation: fentanyl 25–100 mcg/h or 1–2 mcg/kg bolus; propofol 5–50 mcg/kg/min (if BP holds); ketamine 1–2 mg/kg/h; midazolam 0.02–0.1 mg/kg/h.

How long can they stay apnoeic? (time to SpO2 90% after full preoxygenation)

Patient	Approx. safe apnoea	Why
Healthy adult	~8 min	Large FRC full of oxygen, normal consumption
Critically ill / septic	~2–5 min, often less	Shunt, high O2 use; preoxygenation works poorly
Obese	~3 min	Small FRC, high O2 use, atelectasis
Small child	~3.5 min	Double the O2 use per kg
Room air, no preox	~1 min	Lungs hold mostly nitrogen

Below 90% the curve falls off a cliff: the store is gone and haemoglobin unloads fast. Pulse oximetry lags the blood by ~20–30 s, so the number on the screen is the past.

The bench is a teaching model built on Benumof's apnoea curves and textbook onset and offset times. It teaches timing, not dosing for a real patient. Follow local protocol.