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Step 20 · Preop & Exam

The Airway Exam

Predicting the difficult airway before you ever pick up the blade.

5 min read

The TL;DR

  • Do an airway exam on every patient, ideally seated — it predicts difficult mask ventilation and intubation.
  • Four parts: neck flexion/extension, thyromental distance, mouth opening, and Mallampati class.
  • Mallampati I–IV: the less you see (down to hard palate only), the higher the chance of a difficult intubation.
  • No single finding predicts a difficult airway — weigh them together, especially after head/neck surgery or radiation.
  • The Mallampati isn't validated in small children; in peds you mostly get thyromental distance, maybe neck/mouth opening.

01The four parts

The airway exam predicts when mask ventilation and/or intubation might be hard. Do it on every patient, seated when possible:

  1. Neck flexion & extension — have the patient flex and extend; limited movement suggests a harder intubation.
  2. Thyromental distance — finger-breadths from the thyroid notch to the chin; shorter = harder.
  3. Mouth opening — any limitation?
  4. Mallampati class — what you can see inside the open mouth.
Cormack–Lehane laryngeal viewIFull glottisIIPosterior cordsIIIEpiglottis onlyIVSoft palate onlyGrade I–II → intubate. Grade III–IV → bougie, optimize position/ELM, or video laryngoscopy.
swipe diagram horizontally →
A poor pre-op airway predicts a poor laryngoscopic view — plan accordingly.

02The Mallampati classes

With the patient seated and the mouth wide open:

ClassYou can see
ISoft palate, fauces, uvula, and tonsillar pillars
IISoft palate, fauces, uvula
IIISoft palate and base of uvula
IVHard palate only

The higher the class, the higher the probability of a difficult intubation — but no single indicator stands alone. Take all four findings (plus body habitus, beard, prior difficulty) together, and be especially wary after head/neck surgery or radiation.

Pearls
  • The Mallampati and most of the exam aren't validated in infants/children — in peds rely on thyromental distance and general assessment.

Concepts adapted for AnesthesiaHub from “Anesthesia Made Easy” (Jeff Steiner, DO, MBA) and standard anesthesia references, re-expressed in this site's own words. Educational use only — always verify doses against primary sources and your institution's protocols.

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