Perioperative Guide
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Perioperative Airway Management

Case-based clinical reasoning for airway risk — integrate difficult airway predictors, ventilation and aspiration risk, induction strategy, rescue planning, and extubation safety.

Try the tool first

Start with a structured airway assessment. Use airway predictors, ventilation risk, aspiration risk, and backup planning to decide whether the airway plan should change before induction.

Assess airway risk

How to use this page

  1. 1.Interpret the risk signal — Difficult-intubation predictors, mask-ventilation risk, aspiration risk, and rescue feasibility each mean something different.
  2. 2.Understand the clinical meaning — A positive predictor is a planning trigger, not a diagnosis — what matters is oxygenation reserve and the backup ventilation strategy.
  3. 3.Change the plan — Decide what should change before induction, during rescue planning, and at extubation.

Tools to use alongside this page

LEMON Airway AssessmentSTOP-BANG (OSA)Awake Intubation Decision

Start with airway risk

Difficult airway prediction: a signal, not a diagnosis

A positive predictor changes preparation, not the diagnosis. Separate intubation difficulty, ventilation and oxygenation risk, rescue feasibility, aspiration risk, and extubation risk.

How to assess a difficult airway before anesthesia

Use LEMON and key airway findings to turn the preoperative exam into an induction, oxygenation, rescue, and extubation plan.

Ventilation and oxygenation risk

Obesity and OSA: airway risk is also oxygenation risk

Reduced oxygenation reserve, difficult mask ventilation, and postoperative obstruction risk — not only intubation difficulty. Successful intubation does not end the airway risk.

Preoxygenation and apneic oxygenation: buying time

Plan oxygen reserve before the first attempt — positioning, mask seal, PEEP/CPAP, HFNO, and when oxygen support is not enough.

Aspiration risk and induction strategy

Aspiration risk and induction strategy: when does the plan change?

RSI is not automatically the safest approach when aspiration risk and difficult-airway predictors coexist. The plan should integrate both dimensions.

Induction and rescue planning

Awake intubation: when should it be considered?

A positive predictor is a planning trigger — not an automatic indication. When does preserving spontaneous breathing change the safety margin?

Cannot intubate / cannot oxygenate: plan before crisis

CICO planning belongs before induction. Ask whether you can oxygenate, mask ventilate, use an SGA, and access the front of the neck — before the first attempt.

Video laryngoscopy: first-line or rescue?

VL can be a planned first-line device in selected patients — but it does not eliminate the need for a backup ventilation strategy, oxygenation plan, or rescue pathway.

Extubation and postoperative airway

Extubation after a difficult airway: the last airway decision

Airway risk does not end when the tube is placed. Extubation strategy — delayed, staged, or over an exchange catheter — requires the same planning rigour as intubation.

Think through a case

Obesity, Mallampati IV, and limited neck mobility

Multiple predictors of difficult laryngoscopy and difficult mask ventilation. How should the plan change before induction?

Post-radiation neck surgery: when failure is not an option

Distorted anatomy where failed laryngoscopy and failed mask ventilation can occur together. Plan for failure before induction.

Stridor at rest and a laryngeal tumor

The lumen is already critically narrow. A case on why induction can remove the last airway tone holding it open.

Full stomach with predicted difficult airway: RSI or awake strategy?

Aspiration risk alone does not determine the induction plan. When full stomach risk coexists with predicted difficult intubation, the plan must integrate both risk dimensions.

Post-extubation obstruction in PACU: the airway decision is not over

Successful intubation does not end the airway risk. Extubation and PACU monitoring are part of the airway plan — especially when reintubation may be difficult.

Foundational overview

Level 1 — Quick Learn

Medical students and junior residents

What is LEMON?

LEMON is a simple bedside assessment used to predict difficult laryngoscopy and intubation before airway management.

LEMON is not a scoring system — it is a structured way of thinking about airway risk.

L — Look externally

Check for visible features that may suggest difficulty:

  • Facial abnormalities
  • Obesity
  • Beard
  • Short neck
  • Poor dentition

These features may interfere with mask ventilation or laryngoscopy.

E — Evaluate (3-3-2 rule)

Assess airway geometry using finger breadths:

  • Mouth opening — ≥3 finger breadths
  • Mandibular space — ≥3 finger breadths
  • Thyromental distance / laryngeal position — ≥2 finger breadths

Reduced space suggests limited room for laryngoscope manipulation.

M — Mallampati classification

Evaluate visibility of oropharyngeal structures. Higher class (III–IV) suggests:

  • Limited visualization of the glottis
  • Increased difficulty in glottic exposure

O — Obstruction

Look for conditions such as:

  • Tumors
  • Infection
  • Edema

Obstruction may cause difficulty in ventilation and inability to intubate — this is a high-risk finding.

N — Neck mobility

Assess ability to extend the neck. Limited mobility prevents alignment of:

  • Oral axis
  • Pharyngeal axis
  • Laryngeal axis

This makes laryngoscopy more difficult.

How to interpret LEMON

No single finding defines a difficult airway. Risk increases when:

  • Multiple abnormalities are present
  • Or critical findings exist — such as obstruction

Clinical meaning

LEMON does not answer: 'Is intubation possible?' It helps answer: 'How should I prepare?'

Key takeaway

LEMON is not about prediction alone — it is about preparation.