Predicting a difficult airway: Mallampati, mouth opening, neck and jaw
- Assessment
Before anaesthesia the doctor looks at the mouth, jaw and neck to predict whether breathing for the patient or placing a tube will be hard.
What it is
Airway assessment tries to predict four difficulties before they happen: difficult mask ventilation, difficult laryngoscopy and intubation, difficult supraglottic airway placement and difficult front-of-neck access. The history asks about previous difficult airways (the strongest single predictor), snoring and sleep apnoea, radiotherapy or surgery to the neck, and conditions that stiffen the neck or enlarge the tongue. The examination looks at the face (beard, missing teeth, receding jaw), mouth opening, the Mallampati class, the thyromental distance, the ability to slide the lower jaw forward (upper lip bite test), neck movement and neck circumference. The Mallampati class is seen with the patient sitting, mouth fully open and tongue out without speaking: class I shows the soft palate, fauces, uvula and pillars; II the soft palate, fauces and uvula; III the soft palate and base of the uvula; IV only the hard palate. No single sign predicts well on its own; several together raise the probability. Because prediction is imperfect, every anaesthetic needs a plan for the unexpected difficult airway.
What to assess
- History: previous difficult airway, snoring and sleep apnoea, head and neck radiotherapy or surgery, tumours, trauma, rheumatoid arthritis.
- Face and teeth: beard, missing, loose or prominent teeth, receding or small lower jaw, facial trauma.
- Mouth opening and Mallampati class.
- Jaw: thyromental distance and the ability to bite the upper lip with the lower teeth (jaw protrusion).
- Neck: extension and flexion, circumference, scars, masses and stiffness.
- Conditions that raise risk: obesity, pregnancy, acromegaly, Down syndrome, cervical spine disease, airway infection or swelling.
How it is done (and why)
- Ask about earlier anaesthetics and look for an airway alert — a known difficult airway is the best predictor there is.
- Ask about snoring, daytime sleepiness and witnessed apnoeas — sleep apnoea predicts difficult mask ventilation.
- Inspect the face, beard, teeth and jaw — they affect the mask seal and the line of sight to the larynx.
- Measure mouth opening in fingerbreadths — a small opening limits the laryngoscope and supraglottic devices.
- Grade Mallampati sitting, mouth open, tongue out, no sound — speaking lifts the palate and falsely improves the class.
- Check thyromental distance and jaw protrusion — they show the space into which the tongue is displaced at laryngoscopy.
- Test neck extension and feel the front of the neck — a stiff neck hinders the view; an impalpable cricothyroid membrane hinders rescue.
- Combine the findings and record a plan — several predictors together change the technique, equipment and who is present.
Modified Mallampati classes (sitting, mouth open, tongue out, no phonation)
| Class | Structures seen | Meaning |
|---|---|---|
| I | Soft palate, fauces, whole uvula, tonsillar pillars | Laryngoscopy usually easy |
| II | Soft palate, fauces, uvula | Usually easy |
| III | Soft palate and base of the uvula | Difficulty more likely |
| IV | Hard palate only | Difficulty likely |
Findings that change the plan
- Several predictors or a known difficult airway: plan an awake technique or have advanced devices and a senior anaesthetist present.
- Predicted difficult mask ventilation: optimise preoxygenation and have airway adjuncts and a supraglottic device ready.
- Airway swelling, a mass or stridor: involve senior anaesthesia and surgery early; front-of-neck access may need to be ready.
- Unstable cervical spine: keep the neck still and plan intubation with in-line stabilisation and a video technique.
Next step
- Record every predictor and the overall judgement (expected easy, possibly difficult, known difficult) in the pre-anaesthetic note.
- Call a senior anaesthetist before the day of surgery for any predicted or known difficult airway.
- Agree the airway plan and backup plans, and make sure the equipment and skilled help will be there.
- After a difficult airway, tell the patient, write it in the record and give them a written airway alert for future anaesthetics.
Test yourself
Think of the answer, then tap the question to see it.
How is the Mallampati class correctly assessed?
With the patient sitting, head neutral, mouth fully open and tongue fully protruded, without speaking; the visible structures are graded I to IV.
What does a Mallampati class IV view show?
Only the hard palate: the soft palate and uvula cannot be seen, which predicts a more difficult laryngoscopy.
What is the strongest single predictor of a difficult airway?
A history of a previous difficult airway, which is why old anaesthetic records and airway alerts must be checked.
Which features predict difficult mask ventilation?
A beard, obesity, older age, no teeth, snoring or sleep apnoea and stiff lungs; these make the mask seal and ventilation harder.
Elsewhere in DurgiPedia
- Mouth and pharynx examination
- Opening the airway: head tilt, jaw thrust and simple adjuncts
- Supraglottic airway devices
Connections
Educational content; it does not replace supervised training, your institution's protocols or the anaesthetist's or intensivist's decision. It contains no doses and no ventilator or infusion settings.
Sources: Mallampati Score (StatPearls (NCBI Bookshelf), 2025); Difficult Airway (StatPearls (NCBI Bookshelf), 2026).
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Representative model, for educational purposes only.