The stepwise management of the unanticipated difficult airway — DAS plans A–D, the ASA 2022 difficult-airway guideline, awake tracheal intubation, extubation, and the Indian AIDAA algorithm — is kept with the official guideline diagrams so there is one authoritative source. Open the Guidelines library →
Algorithm diagrams (open in a new tab): 🇬🇧 DAS master ↗ Plan A ↗ Plan B ↗ Plan C ↗ Plan D ↗ 🇮🇳 AIDAA master ↗ AIDAA failed airway ↗
Recent advances
Videolaryngoscopy as default
Growing evidence and guideline support for VL (Macintosh-style and hyperangulated blades) as a first-line device — higher first-pass success, better views, useful in C-spine immobilisation and unexpected difficulty.
HFNO / THRIVE
High-flow nasal oxygen for preoxygenation and apnoeic oxygenation (trans-nasal humidified rapid-insufflation ventilatory exchange) markedly extends safe apnoea time in difficult airways and shared-airway surgery.
Video/optical stylets & combined techniques
Video stylets and VL-plus-flexible-scope combinations rescue the difficult intubation where a good view does not translate into tube passage.
Awake videolaryngoscopy
An accepted alternative to flexible bronchoscopic ATI for selected anticipated difficult airways, with faster set-up.
Second-generation SGAs
Devices with a gastric drain port (i-gel, ProSeal/Supreme) as conduits for intubation and as safer rescue and primary airways.
Airway ultrasound (POCUS)
Bedside cricothyroid-membrane marking, tube-placement confirmation and gastric assessment — see the Ultrasound tab.
Standardised eFONA
The scalpel–bougie–tube cricothyroidotomy is now the single recommended emergency FONA technique, with widespread simulation training.
Human factors & cognitive aids
The Vortex approach, verbalising "declare CICO", checklists and team training — a direct response to the NAP4 lessons on task-fixation.
Sugammadex rescue
Rapid reversal of profound rocuronium block (16 mg/kg) offers a pharmacological "wake-up" option in a can't-intubate situation where rocuronium was used.
Common mistakes
Each extra attempt causes bleeding and oedema, converting a "can't intubate" into a "can't ventilate". Limit to 3 (+1 senior), and change something each time (operator, device, position, adjunct).
The patient dies of hypoxia, not of an unplaced tube. Stop, oxygenate with SGA/facemask, step back and think. Task-fixation is the classic human-factors failure in NAP4.
"No trace, wrong place." A sustained EtCO₂ waveform is the only reliable confirmation of tracheal placement — auscultation and misting mislead. Undetected oesophageal intubation is fatal.
Skipping preoxygenation (or a leaky seal) removes your safety margin. In the obese, pregnant and critically ill, desaturation is precipitous — preoxygenate to EtO₂ >0.85 and use apnoeic oxygenation.
In CICO, waiting "one more attempt" until SpO₂ is in the 40s makes FONA a resuscitation, not a rescue. Declare CICO and cut early.
Where difficulty and risk are predicted (airway tumour, fixed neck, OSMF, severe OSA), an awake technique keeps the patient breathing. Don't remove a marginal airway with a drug you cannot reverse.
Most peri-operative airway complications happen at/after extubation. Stratify risk, fully reverse block (TOF >0.9), extubate awake and upright in at-risk patients, and have a re-intubation plan.
Exam pearls
Q: What is the narrowest part of the airway?
In adults, the glottis (rima glottidis / vocal cords); in children (classically <8 years), the cricoid ring — hence the traditional use of uncuffed tubes, now largely superseded by low-pressure cuffed tubes.
Q: Original vs modified Mallampati?
Mallampati 1985 = 3 classes; Samsoon & Young 1987 added class IV (hard palate only) = the modified 4-class version used today. Classes III–IV predict difficulty.
Q: Describe the laryngeal innervation and the effect of injury.
SLN external branch → cricothyroid (loss = weak voice/no high pitch); SLN internal branch → sensation above the cords (loss = aspiration); RLN → all other intrinsic muscles + sensation below the cords (unilateral = hoarseness; bilateral = stridor/obstruction).
Q: Describe the (upgraded) Cormack–Lehane grades.
1 = most of glottis; 2a partial cords, 2b arytenoids only; 3a epiglottis liftable, 3b adherent; 4 = neither. Grades 2b–4 = difficult laryngoscopy. POGO is the continuous alternative for VL.
Q: Describe an RSI and Sellick's manoeuvre.
Preoxygenate → predetermined induction agent + rapid-onset relaxant (sux 1–1.5 mg/kg or roc 1.2 mg/kg), classically no manual ventilation; cricoid pressure 10 N awake → 30 N asleep, released if it worsens the view/ventilation or the patient vomits; confirm with capnography.
Q: How do you confirm tracheal intubation?
Sustained end-tidal CO₂ over several breaths ("no trace, wrong place"), plus visualising the tube through the cords, bilateral chest rise, auscultation and misting. Ultrasound shows a single air–mucosa interface with bilateral lung sliding.
Q: Suxamethonium vs high-dose rocuronium for RSI?
Sux 1–1.5 mg/kg: fastest on/off but contraindicated in hyperkalaemia, burns/denervation and MH. Rocuronium 1.2 mg/kg: comparable conditions and fully reversible with sugammadex 16 mg/kg (a "can't intubate" rescue).
Q: When is awake tracheal intubation indicated?
The anticipated difficult airway at risk of failed asleep intubation/ventilation — airway tumour, oral submucous fibrosis, fixed cervical spine, severely restricted mouth opening. Confirm placement with capnography before inducing.
References & image credits
- Frerk C, Mitchell VS, McNarry AF, et al. (Difficult Airway Society). DAS guidelines for management of unanticipated difficult intubation in adults 2015. Br J Anaesth. 2015;115:827–848.
- Apfelbaum JL, Hagberg CA, Connis RT, et al. 2022 ASA Practice Guidelines for Management of the Difficult Airway. Anesthesiology. 2022;136:31–81.
- Ahmad I, El-Boghdadly K, Bhagrath R, et al. (DAS). Guidelines for awake tracheal intubation in adults. Anaesthesia. 2020;75:509–528.
- Popat M, Mitchell V, Dravid R, et al. (DAS). DAS guidelines for the management of tracheal extubation. Anaesthesia. 2012;67:318–340.
- Cook TM, Woodall N, Frerk C (4th National Audit Project, RCoA & DAS). Major complications of airway management in the UK (NAP4). Br J Anaesth. 2011;106:617–642.
- Sellick BA. Cricoid pressure to control regurgitation of stomach contents during induction of anaesthesia. Lancet. 1961;278:404–406.
- Birenbaum A, Hajage D, Roche S, et al. (IRIS investigators). Effect of cricoid pressure compared with a sham procedure in RSI (IRIS trial). JAMA Surg. 2019;154:9–17.
- Cook TM. A new practical classification of laryngeal view. Anaesthesia. 2000;55:274–279.
- Roth D, Pace NL, Lee A, et al. Bedside tests for predicting difficult airways: a Cochrane systematic review. Cochrane Database Syst Rev. 2018.
- Kristensen MS, Teoh WH, et al. Ultrasonography for clinical airway management. Anaesthesia / Br J Anaesth. (reviews).
- Gropper MA, et al. (eds). Miller's Anesthesia, 9th Edition. Airway Management in the Adult. Elsevier; 2020.
- Butterworth JF, Mackey DC, Wasnick JD. Morgan & Mikhail's Clinical Anesthesiology, 6th Edition. Airway Management. McGraw-Hill; 2018.
- Barash PG, et al. (eds). Clinical Anesthesia, 9th Edition. Airway Management. Wolters Kluwer; 2023.
Image credits. Airway overview — Wikimedia Commons, public domain. External larynx — Wikimedia Commons, CC BY-SA 2.5. Vocal-cord (glottis) views — Servier Medical Art, CC BY-SA 3.0. Trachea & bronchi — OpenStax Anatomy & Physiology, CC BY 3.0. Modified Mallampati diagram — Jmarchn, CC BY-SA 3.0. Cormack–Lehane figure — User:Tubus, CC BY-SA 3.0 (title cropped). Oropharyngeal (Guedel) airways — Intersurgical Ltd, CC BY-SA 3.0. Nasopharyngeal airway — Wikimedia Commons, CC BY-SA 4.0. LMA & i-gel — Wikimedia Commons, CC BY-SA 4.0. Airway ultrasound images — Osman A, Sum KM, J Intensive Care 2016;4:52, CC BY 4.0 (via PubMed Central). All used with attribution. Difficult-airway algorithm diagrams are shown for educational reference from the respective DAS and AIDAA guidelines.