Airway Assessment

Definition

• The purpose of an airway assessment is to predict and plan for a difficult airway
• The definition of a difficult airway¹ is: “the clinical situation in which a conventionally trained Anaesthesiologist experiences difficulty with facemask ventilation, difficulty in supraglottic device ventilation, difficulty in tracheal intubation or all three” where:
  • Difficulty with facemask ventilation is the inability of an unassisted anaesthesiologist:
    1. to maintain oxygen saturation, measured by pulse oximetry, 92%; or
    2. to prevent or reverse signs of inadequate ventilation during positive-pressure mask ventilation under general anaesthesia
  • Difficult laryngoscopy occurs when “it’s not possible to visualise any portion of the vocal cords with conventional laryngoscopy”
    • This typically corresponds to a Cormack and Lehane Grade IV laryngoscopy view
  • Difficult endotracheal intubation occurs when “proper insertion of the tracheal tube with conventional laryngoscopy requires more than three attempts or more than 10 minutes”

Pre-Operative Airway Assessment

History

• General history elements:
  • Reason for airway protection/management
  • AMPLE history (allergies, medications, past medical history, last meal, events)
  • Exercise capacity
  • Smoker
• Symptoms or risk factors for airway compromise:
  • Stridor, hoarse voice, orthopnoea, drooling, dysphagia
  • Risk factors - suspecterd airway burn, neck trauma, goitre
• Risk factors for difficult airway management: infections of oropharynx and neck (e.g. Ludwig’s angina), problems with mouth opening (e.g. trauma, soft tissue disorders), problems with neck mobility (e.g. cervical spine disruption, rheumatoid arthritis, cervical fusion), , Obesity, OSA, oropharyngeal or neck masses, dentition, pregnancy, recent intubation, angioedema, burns

Chart Review

• Whenever possible identify:
  • The patient’s previous intubation grade and previous difficulties with airway management
  • Determine what techniques and manoeuvres were required to optimise airway management conditions

Examination

• General
  • Level of consciousness and co-operation
  • BMI
• Face: facial hair, craniofacial deformities
• Mouth
  • Mallampati grade
  • Mouth opening (inter incisor distance)
  • Shape of palate
  • Jaw protrusion
• Teeth
  • Teeth prominence
  • Relaxation of maxillary to mandibular incisors during normal jaw closure
  • Dentures/caps/grows/loose teeth
• Neck
  • Range of motion of head and neck
  • Thyro-mental distance <6cm
  • Neck length and circumference/thickness
  • Compliance of mandibular space
  • Sternomental distance

Investigations

• Investigations to consider:
  • Nasal endoscopy
  • Awake laryngoscopy
  • Lateral neck x-ray
  • Chest X-ray
  • CT/MRI neck
• Mallampati score
  • Class I: Soft palate, uvula, fauces, pillars visible
  • Class II: Soft palate, uvula, fauces visible
  • Class III: Soft palate, base of uvula visible
  • Class IV: Only hard palate visible
• Cormack-Lehane Classification
  • Grade 1: Full view of glottis
  • Grade 2a: Partial view of glottis
  • Grade 2b: Only posterior extremity of glottis seen or only arytenoid cartilages
  • Grade 3: Only epiglottis seen, none of glottis seen
  • Grade 4: Neither glottis nor epiglottis seen

• Percentage of visible glottic opening (POGO)
  • It requires the observer to estimate how much of the glottis is not visualised

Mnemonics

• Difficult intubation = LEMON
  • Look externally
  • Evaluate 3-3-2 rule
  • Mallampati score
  • Obstruction
  • Neck Mobility
• Difficult BVM = BONES
  • Beard
  • Obese
  • No teeth
  • Elderly
  • Sleep Apnea / Snoring
• Difficult LMA = RODS
  • Restricted mouth opening
  • Obstruction
  • Distorted airway
  • Stiff lungs or c-spine
• Difficult surgical airway = SHORT
  • Surgery
  • Hematoma
  • Obesity
  • Radiation distortion or other deformity
  • Tumor

Sources

• Airway Assessment • LITFL Medical Blog • CCC Airway - Chris Nickson - Updated July 1 2024 - Accessed 28 August 2026
• Airway Assessment - ANZCA - Bradley, P., Chapman, G., Crooke, B., Greenland, K August 2016 - Accessed 28 August 2026

Footnotes

1. More on the definition of the anatomically difficult airway can be read at Recognition of the anatomically difficult airway ↩