Upper airway obstruction — the cannot-intubate cannot-oxygenate

Assessment. Stridor is the characteristic finding of upper airway obstruction and may be inspiratory, biphasic or expiratory; emergency measures often precede any investigation or precise diagnosis.^[4]

The ED risk. In NAP4, 31 per cent of major ED airway events led to death or persistent neurological injury; gaps were poor identification of at-risk patients, incomplete planning, inadequate staff and equipment, delayed recognition, and failed rescue from absent or misread capnography (contributing to 74 per cent of such outcomes).^[2]

Anticipated difficulty — awake intubation. Awake tracheal intubation has a high success rate and a favourable safety profile but is underused. Topicalisation must be established and tested (lidocaine maximum 9 mg/kg lean body weight); cautious minimal sedation, ideally by an independent practitioner, must not substitute for inadequate topicalisation.^[3]

Unanticipated difficulty — DAS 2015. A maximum of three intubation attempts (a fourth by a more experienced colleague is permissible), then declare failed intubation and move to Plan B (supraglottic airway); if oxygenation via a SAD fails after a maximum of three attempts, Plan C.^[1]

CICO — Plan D: scalpel cricothyroidotomy.

• Fastest and most reliable emergency method; a cuffed tracheal tube protects against aspiration and allows exhalation.^[1]
• Complete neuromuscular block first; neck extension; 100 per cent oxygen to the upper airway throughout.^[1]
• Laryngeal handshake; transverse stab incision through skin and cricothyroid membrane; turn the blade 90° caudally; coude-tip bougie into the trachea; railroad a cuffed 6.0 mm tube; inflate and confirm with capnography.^[1]
• Impalpable membrane: 8–10 cm vertical midline incision, blunt dissection, then the scalpel technique.^[1]

Why not a narrow-bore cannula? Ventilation needs a high-pressure source with significant barotrauma risk, and cannulae fail through kinking, malposition or displacement.^[1]