Predictors of a Difficult Airway

Author: Michelle Lin, MD
Updated: 10/19/2012

Mnemonics: Predictors of a Difficult Airway

Difficult bag mask ventilation (MOANS)

Criteria Finding
Mask seal Bushy beards, crusted blood on the face, or disruption of lower facial continuity
O*besity, *Obstruction Obesity, pregnancy, angioedema, Ludwig’s angina, upper airway abscess, epiglottitis
Age Age >55 years
No teeth Consider leaving dentures in for edentulous patients
S*leep apnea, *Stiff lung COPD, asthma, ARDS

Difficult laryngoscopy and intubation (LEMON)

Criteria Finding
Look externally Use clinical gestalt, evidence of lower facialdisruption, bleeding, small mouth, agitated patient
Evaluate Use the 3-3-2 rule: Mouth opening (3 fingers), mandibular space of chin to hyoid (3 fingers), glottic space of hyoid to thyroid notch (2 fingers)
Mallampati score In order of increasing difficulty (Class I-IV)
O*besity, *Obstruction Obesity = poor glottic views. Note the 4 cardinal signs of upper airway obstruction: Stridor, muffled voice, difficulty swallowing secretions, sensation of dyspnea
Neck immobility Consider using video laryngoscopy (e.g. trauma, arthritis, ankylosing spondylitis)

Difficult extraglottic device (RODS)

  • Restricted mouth opening
  • Obstruction
  • Disrupted or Distorted airway
  • Stiff lung, cervical Spine

Difficult cricothyrotomy (SHORT)

  • Surgery or other airway obstruction
  • Hematoma (includes infection & abscess)
  • Obesity
  • Radiation distortion (and other deformity)
  • Tumor


  • Walls R, Murphy M. 3rd ed. Emergency Airway Management, 2008.