The concept of a difficult airway algorithm

Why we use an airway algorithm

• Airway problems can deteriorate quickly; an algorithm gives a shared, rehearsed plan under pressure.
• It prioritises oxygen delivery over “getting the tube in”.
• It prompts early help, early use of simple rescue techniques, and timely escalation.
• It reduces repeated traumatic attempts and hypoxia-related harm.

Key definitions (new-starter level)

• Difficult airway: difficulty with face-mask ventilation, supraglottic airway (SGA) ventilation, tracheal intubation, or all of these.
• Failed intubation: inability to place a tracheal tube after a limited number of attempts by an appropriately trained clinician.
• Front-of-neck airway (FONA): emergency airway access through the neck (e.g., cricothyroidotomy) when you cannot oxygenate from above.
• CICO (can’t intubate, can’t oxygenate): failure to maintain oxygenation with face mask and SGA; this is a time-critical emergency.

Core principles that run through all difficult airway algorithms

• Oxygenation is the goal; intubation is a means to that goal.
• Call for help early (senior anaesthetist, ODP/assistant, ENT if available, ICU team as appropriate).
• Limit attempts: each attempt risks trauma, swelling, bleeding, and worsening view.
• Optimise before repeating: position, suction, adjuncts, technique, and equipment.
• Use capnography to confirm ventilation and tracheal intubation whenever possible.
• Have a clear “stop point” where you change plan rather than repeating the same attempt.

Preparation: what to do before induction (especially if difficulty is possible)

• Assess airway briefly but systematically: mouth opening, neck movement, jaw protrusion, teeth/dentures, beard, obesity, pregnancy, reflux, previous anaesthetic records.
• Plan A–D in your head (and out loud): primary technique, backup, rescue oxygenation, and emergency FONA.
• Pre-oxygenate well: tight mask seal, head-up if possible; aim for high end-tidal oxygen if monitored.
• Position: “sniffing” or head-elevated laryngoscopy position; ramp obese patients so ear-to-sternal-notch alignment is achieved.
• Check equipment: suction on and within reach; working laryngoscope; bougie; appropriately sized tubes; SGA; capnography; difficult airway trolley location.
• Brief the team: who will apply cricoid (if used), who will assist, what words will be used to declare failure and call help.

A simple stepwise model (conceptual Plan A–D)

• Plan A: initial intubation strategy (e.g., video or direct laryngoscopy) with best first attempt (position, suction, bougie ready).
• Plan B: maintain oxygenation with an SGA if intubation fails; consider waking the patient if safe and appropriate.
• Plan C: face-mask ventilation if SGA fails; reduce complexity, optimise seal, use two-person technique, consider waking if possible.
• Plan D: emergency FONA if you cannot oxygenate (CICO) — do not delay once CICO is declared.

Plan A: making the first attempt count

• Use the most reliable technique available to you (often video laryngoscopy for predicted difficulty, depending on local practice).
• Optimise conditions: full paralysis if appropriate, adequate depth of anaesthesia, and good positioning.
• Use external laryngeal manipulation and suction early; blood/secretions rapidly worsen the view.
• Use a bougie early if the view is limited; don’t persist with repeated blind passes.
• Set an attempt limit (commonly 3 attempts total, with a change in operator/technique for subsequent attempts); stop earlier if oxygenation is deteriorating.

Plan B: supraglottic airway (SGA) rescue

• Aim: restore oxygenation and ventilation quickly.
• Choose an appropriate SGA size; insert gently; confirm ventilation with chest rise and capnography.
• If ventilation is adequate: consider waking the patient, proceeding with surgery using the SGA (case-dependent), or intubating via the SGA if skilled and equipped.
• If ventilation is not adequate: reposition, adjust depth, consider a different SGA size/type, and limit repeated insertions.

Plan C: face-mask ventilation rescue

• Use two-person technique early: one person holds mask/jaw thrust with both hands; the other ventilates.
• Use airway adjuncts: oropharyngeal airway (OPA) and/or nasopharyngeal airway (NPA) if appropriate.
• Re-check head/neck position, mask seal, and obstruction (e.g., laryngospasm, biting, secretions).
• If you can ventilate: consider waking the patient and reassessing the plan.

Plan D: CICO and emergency front-of-neck airway (FONA)

• Declare CICO clearly: “Can’t intubate, can’t oxygenate”. This triggers immediate team action.
• Call for the difficult airway trolley and senior help if not already present; allocate tasks (oxygenation attempts vs preparing neck access).
• Proceed promptly to emergency FONA according to local policy (commonly scalpel-bougie cricothyroidotomy in adults).
• After FONA: confirm ventilation with capnography, secure the airway, and stabilise; plan definitive airway and post-event care.

Human factors: staying safe under stress

• Use closed-loop communication: ask for actions and confirm they are done.
• Say the plan out loud: “Plan A… if that fails, Plan B…”.
• Avoid fixation: if the same thing isn’t working, change something meaningful (operator, device, technique, patient position).
• Keep situational awareness: oxygen saturation trend matters more than the laryngoscopy view.

Common first-time scenarios and what to do

• Unexpected poor view at laryngoscopy: stop, re-oxygenate, optimise position, suction, use bougie/video, and consider changing operator early.
• Can’t ventilate with mask initially: insert OPA/NPA, two-person technique, check for laryngospasm, deepen anaesthesia, ensure adequate paralysis if appropriate.
• SGA won’t ventilate: reposition head/neck, adjust depth, check for leak/obstruction, try different size/type, then move on rather than repeated attempts.
• Rapid desaturation (obesity, pregnancy, sepsis): prioritise oxygenation, minimise apnoea time, consider early SGA rescue, and call for senior help early.