Anaes · Airway management & difficult airway

The difficult airway & rapid sequence induction

Also known as Difficult airway · Difficult intubation · Unanticipated difficult airway · Rapid sequence induction · RSI · Can't intubate can't oxygenate

The difficult airway is a core examination topic, and the one in which failure kills. The framework rests on four ideas: predict where you can (LEMON, MACOCHA), optimise every attempt (position, preoxygenation, paralysis), and follow a fixed rescue sequence when intubation fails — the Difficult Airway Society Plans A through D, a ladder that ends in emergency front-of-neck access when the patient can no longer be oxygenated. The physiology underpinning it all is the safe apnoea period: preoxygenation denitrogenates the functional residual capacity into an oxygen reservoir, and apnoeic oxygenation (classically transnasal humidified rapid-insufflation ventilatory exchange, THRIVE) can extend that window many-fold — buying the calm, planned best attempt that prevents a spiral into crisis. Built around the landmark guidelines (DAS 2015, ASA 2022, AIDAA, the DAS/ICS critically-ill guideline), the national audit NAP4, the Vortex approach, and the trials that have redrawn practice — the IRIS trial showing cricoid pressure does not reduce aspiration, the Cochrane review and the INTUBE study on videolaryngoscopy, and the MACOCHA score for the predicted-difficult intubation in the ICU.

Checked against its sources on 11 Sept 2026