Anticipated difficult airway and the ASA algorithm

Airway·~5 min read· Physician-reviewed✓ Sourced · 5

Stem

A 54-year-old woman, 84 kg, is scheduled for an elective total thyroidectomy for a multinodular goiter without tracheal compression on CT. A note from her hysterectomy five years ago reads "grade 3 view, intubated on the second attempt with a bougie." She has a receding mandible, Mallampati 3, a thyromental distance of 5 cm and full neck extension. She has no beard, no snoring, no reflux and a normal mouth opening.

Question

How will you plan to secure her airway?

Ideal answer

HeadlinePredicted difficult laryngoscopy but nothing predicts difficult oxygenation, so I induce her rather than intubate awake, video laryngoscope first.

Assess four things first. Difficult laryngoscopy, mask ventilation, supraglottic airway placement, front-of-neck access: no beard, no sleep apnea, good mouth opening, and the goiter not compressing her trachea.
Supraglottic airway and flexible scope opened, colleague present, so plan B is in hand.
Preoxygenate to end-tidal oxygen fraction about 0.9, nasal oxygen through the attempt, for the longest safe apnea.
Full intubating dose of rocuronium, sugammadex drawn up; three laryngoscopy attempts, a fourth only by a more experienced colleague; I declare failure early.¹
Before induction, I state my exit aloud: supraglottic rescue, wake her if I can, front-of-neck access if I cannot oxygenate; cricothyroid membrane marked beforehand.

Watch for: oxygen saturation; it, not the view, decides the next step.

Breaking down the answer

Awake versus asleep — judgment first. Awake when difficult intubation comes with difficult ventilation, high aspiration risk, intolerance of even brief apnea, or expected difficult front-of-neck rescue: breathing guarantees oxygenation.² Changes if: uncooperative patient, child or bleeding airway, then an induction preserving spontaneous breathing.
Preoxygenation and apneic oxygenation — good preoxygenation extends safe apnea in a healthy adult from 1–2 minutes to as long as 8; nasal oxygen at up to 15 L/min during laryngoscopy prolongs it further;³ high-flow nasal oxygen is an alternative.²
Video laryngoscopy first — in predicted difficult airways it gives better views and more successful intubations than direct laryngoscopy;² a hyperangulated blade with a styleted tube suits an anterior larynx.
Why stop at three — each attempt adds edema and bleeding; then I declare failed intubation and move to a second-generation supraglottic airway or wake the patient.¹ Between attempts I change operator, blade, position or relaxant.
Full relaxation — rocuronium 1.2 mg/kg,⁴ because a paralyzed patient is easier to intubate and mask, and further attempts should not proceed without full block.³ Sugammadex 16 mg/kg is the labeled dose for reversal soon after that dose.⁵
Use the structure, do not recite it — the 2022 ASA guidelines give the framework; the examiner wants it applied to this patient (organization).²

Follow-up question

You induce her and the video laryngoscope shows only epiglottis, with blood in the pharynx after the first attempt. The saturation is 95%. What do you do?

Follow-up answer

HeadlinePlan A is failing: epiglottis only and blood after one attempt. I call for help and say so.

Two-hand mask ventilation, oral airway in, saturation above 90% before another attempt. Attempt two changes the tool: a bougie under direct view, or a hyperangulated blade with suction, with her repositioned. If that fails, I place a second-generation supraglottic airway, ventilate, and decide: wake her with sugammadex, because this surgery is elective, or intubate through it with a flexible scope if surgery could not wait. If at any point I cannot oxygenate, I stop troubleshooting and perform a scalpel-bougie cricothyrotomy, saying so before the saturation forces it. Afterward I document, tell her and register the airway.²

Four laryngoscopic views: grade 1 shows the whole glottis, grade 2 only the posterior glottis and arytenoids, grade 3 only the epiglottis, and grade 4: neither epiglottis nor glottis visible, the tongue base fills the view. — Cormack–Lehane grade is the best laryngoscopic view of the glottis. Grade 4: neither epiglottis nor glottis visible. · Boards Academy diagram

Four side-view steps: stab incision through the cricothyroid membrane, rotate the blade so the edge points caudally, slide a bougie along the blade into the trachea, then railroad a 6.0 cuffed tube and confirm with capnography. — Scalpel, bougie, tube: stab, rotate and open, bougie, 6.0 cuffed tube. · Boards Academy diagram

Pitfalls that cost points

Reciting the algorithm as a flow chart instead of applying it to the patient in the stem.
Choosing asleep intubation with stridor or a fixed obstruction because "video laryngoscopy usually works".
"Keeping it light": a half-relaxed patient is the worst of both worlds, harder to intubate and to mask.

Rapid-fire

Q: Why not a flexible scope asleep with a large tongue-base tumor? A: Induction removes pharyngeal tone and the tumor obstructs completely; awake, the patient maintains the only airway that exists.

Q: What predicts difficult mask ventilation? A: Beard, BMI above 30, age over 55, edentulous, snoring or sleep apnea, Mallampati 3–4, and neck radiation; no single one is reliably more predictive,² so two or more raise my threshold for inducing.

Q: When is a supraglottic airway the wrong rescue? A: Fixed obstruction at or below the glottis, mouth opening below 2 cm, and a full stomach, where it buys oxygenation but not protection.

Q: Why does sugammadex not solve a cannot-oxygenate situation? A: Reversal takes minutes and does not guarantee a patent airway¹ or spontaneous ventilation;³ with no oxygen reserve, that is time I do not have.

Numbers to know

Item	Value
Preoxygenation target	End-tidal O2 fraction 0.87–0.9³
Apneic oxygenation	Nasal cannula up to 15 L/min, or HFNO
Laryngoscopy attempts	3, plus 1 by a more experienced operator¹
Rocuronium for intubation	1.2 mg/kg
Sugammadex for immediate reversal	16 mg/kg⁵
Mouth opening for supraglottic airway	≥ 2 cm interincisor

Sources

1.Difficult Airway Society 2025 guidelines for management of unanticipated difficult tracheal intubation in adults · DAS, 2025 · sea.org.ecAhmad et al., Br J Anaesth 2026;136:283-307 (online 7 Nov 2025), doi 10.1016/j.bja.2025.10.006; full English text hosted by the Sociedad Ecuatoriana de Anestesiología. Replaces DAS 2015 for attempts, eFONA technique (vertical incision default) and sugammadex.
2.2022 American Society of Anesthesiologists Practice Guidelines for Management of the Difficult Airway · ASA, 2022 · asa2.silverchair.com
3.Difficult Airway Society 2015 guidelines for management of unanticipated difficult intubation in adults · DAS, 2015 · ebi.ac.ukFull text via Europe PMC (PMC4650961). DAS published a 2025 update (Br J Anaesth) that could not be accessed for verification.
4.Rocuronium bromide injection prescribing information · FDA / DailyMed · dailymed.nlm.nih.govRapid sequence intubation dose 0.6-1.2 mg/kg.
5.BRIDION (sugammadex) injection prescribing information · FDA / DailyMed · dailymed.nlm.nih.gov

Facts on this page were checked against these sources on Oct 14, 2026. Guidelines change; confirm doses against current institutional protocols.