Rapid Sequence Intubation
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Direct answer
Rapid sequence intubation (RSI) is the technique for securing an endangered airway in a patient at risk of aspiration: after thorough preparation and preoxygenation, a rapidly acting induction agent and a neuromuscular blocker are given in sequence and the trachea is intubated without intervening mask ventilation, with waveform capnography confirming placement. Drug choice is tailored to physiology — ketamine or etomidate for the unstable, propofol for the fit and normotensive — with succinylcholine or rocuronium 1.2 mg per kilogram for relaxation, respecting succinylcholine's hyperkalaemia contraindications.
What you must remember
- Preparation and preoxygenation: check equipment (suction, two laryngoscopes, tubes of two sizes, bougie, bag-valve-mask), position head-up and ramped, attach monitors and intravenous access; preoxygenate with 100 per cent oxygen for three minutes of tidal breathing or eight vital-capacity breaths, with nasal apnoeic oxygenation at 15 litres during laryngoscopy to extend the safe apnoea time.
- Induction agents: ketamine 1 to 2 mg per kilogram preserves pressure and bronchodilates — preferred in shock, bronchospasm (though it increases secretions); etomidate 0.3 mg per kilogram is haemodynamically neutral but transiently suppresses the adrenal axis; propofol 1 to 2.5 mg per kilogram is smooth but drops the pressure, avoided in shock; dosing is reduced in the elderly and the ill.
- Neuromuscular blockers: succinylcholine 1 to 1.5 mg per kilogram depolarises — onset about 45 seconds, offset six to ten minutes, with fasciculations, myalgia, bradycardia in children and the risk of hyperkalaemia; rocuronium 1.2 mg per kilogram matches its onset for roughly 30 to 60 minutes and is reversible with sugammadex.
- Succinylcholine contraindications: known hyperkalaemia, burns beyond the initial day, crush injury, prolonged immobilisation, denervation and stroke after the first 48 hours, neuromuscular disease, and a history of malignant hyperthermia — rocuronium is the alternative in all.
- Cricoid pressure (Sellick manoeuvre) was routine for aspiration prophylaxis, but current practice questions its benefit and tolerates its interference with the laryngoscopic view — apply it cautiously and release if the view is poor.
- Confirmation and post-intubation care: continuous waveform capnography is the standard of confirmation (sustained carbon dioxide over six breaths), supplemented by bilateral breath sounds, tube depth of roughly 21 cm at the teeth in women and 23 in men, and a chest radiograph; then sedation and analgesia before or with any paralysing infusion, ventilator connection, and a nasogastric tube for gastric decompression.
- The failed airway: after failed attempts and failed oxygenation, insert a supraglottic airway for oxygenation and proceed to a scalpel cricothyroidotomy — a front-of-neck access that every operator must be able to perform.
Walking the sequence through
A drunk 40-year-old with a head injury and a full stomach needs his airway now. Prepare: Preoxygenate with 100 per cent oxygen for three minutes (or eight vital-capacity breaths) head-ramped, with nasal apnoeic oxygenation at 15 litres. Induce to the physiology: this patient is hypertensive and bronchospastic, so ketamine preserves pressure and bronchodilates; etomidate is the neutral alternative, while propofol in a shocked patient is the planted wrong option. Relax with succinylcholine 1 to 1.5 mg per kilogram unless he carries a hyperkalaemia contraindication — then rocuronium 1.2 mg per kilogram, reversible with sugammadex. Intubate without intervening mask ventilation, cricoid pressure applied cautiously if at all. Confirm with continuous waveform capnography over six breaths — auscultation alone is the perpetual trap — check depth (21 cm in women, 23 in men), then sedate and analgese before any paralysing infusion. If the airway and oxygenation both fail: supraglottic airway, then scalpel cricothyroidotomy.
Where students slip
The classic error is succinylcholine in the burnt or crushed patient — potassium from upregulated receptors can arrest the heart, and the exposure window is what the stem hides. Ketamine's indications trip students who remember its secretions but forget it is the safe choice in shock and severe asthma. Capnography is the standard, not listening. And the viva favourite is paralysing without sedation and analgesia.
Frequently asked questions
What is rapid sequence intubation?
A cricoid-era technique of preoxygenation, rapid induction with a neuromuscular blocker, and intubation without intervening mask ventilation, designed to minimise aspiration in the non-fasted patient.
Which patients must not receive succinylcholine?
Those with or at risk of hyperkalaemia — burns beyond 24 hours, crush injury, denervation, prolonged immobility, stroke after 48 hours, neuromuscular disease — and malignant hyperthermia history.
What dose of rocuronium is used for RSI?
1.2 mg per kilogram intravenously, giving intubating conditions in about a minute for 30 to 60 minutes, reversible with sugammadex.
How is correct tube placement confirmed?
Continuous waveform capnography showing sustained expired carbon dioxide, supported by bilateral breath sounds, tube depth and a chest radiograph.
Why choose ketamine in the shocked or asthmatic patient?
It maintains blood pressure through sympathetic stimulation and is a bronchodilator, unlike propofol, which causes hypotension.
What is the rescue when intubation fails?
Oxygenate with a supraglottic airway and, if that fails, perform a scalpel cricothyroidotomy as the definitive front-of-neck airway.