Anaes · Airway management
The unanticipated difficult airway: the DAS 2015 algorithm and the Vortex approach
Also known as DAS 2015 algorithm · Difficult Airway Society algorithm · Vortex approach · CICO · Cannot intubate cannot oxygenate · Front-of-neck access · FONA · Scalpel-bougie cricothyroidotomy
The unanticipated difficult airway is the airway that fails on induction, in a patient the preoperative assessment did not flag, and it is the single most examined emergency in the airway viva because it is the crisis that kills. Two frameworks now govern the response, and the candidate must know both. The Difficult Airway Society 2015 algorithm is the structured, sequential UK standard — Plan A the optimised initial intubation, capped at three attempts; Plan B the second-generation supraglottic airway rescue; Plan C the final face mask ventilation attempt; and Plan D the cannot-intubate, cannot-oxygenate endpoint at which front-of-neck access is performed without delay. The Vortex approach of Chrimes is the simplified cognitive tool that arranges the same three lifelines — face mask, supraglottic airway, endotracheal tube — as converging lanes around a central CICO zone, each capped at three best attempts, designed for crisis resource management and universal applicability across anaesthesia, the emergency department, and intensive care. This suite examines the two frameworks against each other, the scalpel-bougie cricothyroidotomy technique, the human factors that decide the outcome, and the preoxygenation and the safe apnoea period that buy the time the algorithm runs in. Anchored to contemporary evidence on the physiological difficult airway, the safety of the emergency intubation, the syndromic difficult airway, and the measured preoxygenation.
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Red flags
- Perseverance is the fatal error of the unanticipated difficult airway. Each repeated laryngoscopy traumatises and swells the airway, worsens the view, and burns the safe apnoea time. The DAS algorithm and the Vortex both cap attempts at three per lifeline or per plan; the candidate who pushes beyond three has failed the discipline, not mastered the airway.
- CICO is a cannot-intubate, cannot-oxygenate state in which death follows within minutes of hypoxia. The moment both intubation and oxygenation have failed across the lifelines, front-of-neck access is performed immediately — the recurring, avoidable failure of the national audits is that the scalpel cricothyroidotomy is performed too late.
- A second-generation supraglottic airway is the Plan B rescue; a first-generation device is not. The national audit found first-generation laryngeal masks failed as rescue in the major events, and they must not be relied on when the airway is lost.
- Capnography is mandatory at every step, not optional. The absence of a continuous waveform CO2 trace has caused unrecognised oesophageal intubation and death, and the algorithm requires it for confirmation through a tube or a supraglottic airway alike.
- The physiological difficult airway shortens the safe apnoea period to seconds. The hypoxaemic, shocked, or acidotic patient desaturates before the tube is placed, and the preoxygenation must be measured and maximal before induction.
Meet the patient
A fasted, apparently normal patient is induced for an elective hernia repair. The laryngoscope finds a Grade 4 view you did not predict. The patient is apnoeic and paralysed, the saturation clock is running, and the next three minutes decide whether this is a story you tell at a meeting or one told about you.[3]
The question the unanticipated difficult airway forces is whether you have the discipline to stop persevering and move through the plans. Oxygenation, not intubation, is the objective — and the recurring, avoidable failure is that the scalpel comes too late.[3][1]
References6ShowHide
- [1]Ghaffar S, et al. Physiological difficult airway management in the emergency department J Pak Med Assoc, 2026.PMID 42363338
- [2]Black KM, et al. Anesthesia Care, Complications, and Airway Management for Patients With Spinal Muscular Atrophy: A Retrospective Chart Review From a Quaternary Children's Hospital Anesth Analg, 2026.PMID 42363899
- [3]Freund Y, et al. Improving the safety of emergency tracheal intubation Curr Opin Crit Care, 2026.PMID 42170830
- [4]Caputo ND, et al. End Tidal O(2): A Promising New Metric for Optimizing Preoxygenation and RSI Safety in the Emergency Department Acad Emerg Med, 2026.PMID 42340046
- [5]Sheridan B, et al. Maintenance of prehospital anaesthesia using an intermittent bolus regime in blunt trauma patients with a high GCS and hemodynamic reserve: a retrospective cohort study Scand J Trauma Resusc Emerg Med, 2026.PMID 42351216
- [6]Merchant N, et al. Comparing the analgesic utility & safety of erector spinae plane block versus thoracic epidural for multiple rib fracture trauma: a retrospective cohort analysis Injury, 2026.PMID 42361789