Rapid Sequence Intubation Drug Selection

Rapid sequence intubation gives an induction agent and a neuromuscular blocker in quick succession to secure the airway in a patient at risk of aspiration or deterioration. Drug choice depends on haemodynamic state, the indication and contraindications to suxamethonium.

Preparation. Resuscitate before induction: preoxygenate, correct hypotension, and have a vasopressor running or drawn up. Plan the post-intubation sedation before drugs are given.

Dose by weight. Suxamethonium uses total body weight. Propofol uses lean body weight. For rocuronium, ideal body weight is used in obesity and some practice uses adjusted weight for rapid sequence doses.

Induction agent.

• Ketamine: preferred in shock and most emergencies.

• Etomidate: haemodynamically stable alternative, with the concern that a single dose causes transient adrenal suppression.

• Propofol: in stable patients, with a lower dose in shock.

Neuromuscular blocker. Rocuronium or suxamethonium. Rocuronium is preferred when sugammadex is available or suxamethonium is contraindicated.

Suxamethonium contraindications. Potassium over 5.5 mmol/L, burns or crush injury more than 24 to 72 hours old, prolonged immobility, spinal cord injury over 48 hours old, neuromuscular disease, personal or family history of malignant hyperthermia, and known pseudocholinesterase deficiency.

Special groups.

• Children: suxamethonium 2 mg/kg in infants, with atropine 20 micrograms/kg in younger children.

• Pregnancy: high aspiration and difficult airway risk, so use an experienced operator.

• Older adults: reduce induction doses.

• East Africa: ketamine is often the most available induction agent where monitoring is limited.

• Ketamine: 1 to 2 mg/kg intravenously (0.5 to 1 mg/kg in shock).

• Etomidate: 0.3 mg/kg intravenously.

• Propofol: 1 to 2 mg/kg intravenously (0.5 to 1 mg/kg in shock).

• Rocuronium: 1.2 mg/kg intravenously.

• Suxamethonium: 1.5 mg/kg intravenously (1 to 1.5 mg/kg).

• Fentanyl: 1 to 3 micrograms/kg, avoided in shock.

• Push-dose pressor: phenylephrine 50 to 100 micrograms, or adrenaline 5 to 20 micrograms (10 micrograms/mL), repeated every 2 to 5 minutes.

• Sugammadex: 16 mg/kg for immediate reversal after rocuronium 1.2 mg/kg. Use 4 mg/kg when the train-of-four count is 1 to 2.

Monitoring. Use continuous oximetry, ECG, capnography and blood pressure every 1 to 2 minutes. Give analgesia and sedation as soon as the airway is secure, because rocuronium lasts 45 to 70 minutes.

Stop rules. Stop the sequence and return to bag-mask oxygenation for desaturation under 90 percent, bradycardia or hypotension during laryngoscopy.

Referral and escalation. In a failed airway where oxygenation fails, move straight to front of neck access. For suspected malignant hyperthermia, give dantrolene 2.5 mg/kg intravenously, repeat 1 mg/kg to a maximum of 10 mg/kg, stop triggers, and cool. Call senior airway help early.

Common errors. Inducing a shocked patient with propofol at full dose, giving suxamethonium in hyperkalaemia, forgetting post-intubation sedation, and not having a vasopressor ready.