Airway Assessment

Quick Answer

Systematic airway assessment identifies 80-90% of difficult airways but has limited positive predictive value (~10-15%), meaning many predicted difficult airways are easily managed and some predicted easy airways prove difficult. The LEMON criteria provide a structured approach: Look externally (facial asymmetry, obesity, beard), Evaluate 3-3-2 rule (mouth opening >3 cm, thyromental distance >3 fingerbreadths, sternomental distance >2 fingerbreadths), Mallampati classification (I-IV with 60-70% sensitivity), Obstruction (tumours, infection, haematoma), Neck mobility (atlanto-occipital extension <35° predicts difficulty). The 3-3-2 rule has 80-90% specificity for difficult intubation. Mallampati score combined with thyromental distance improves prediction (sensitivity 60-70%). Video laryngoscopy (C-MAC, Glidescope) improves laryngeal view by 1-2 Cormack-Lehane grades compared to direct laryngoscopy, with first-attempt success rates >90% even in predicted difficult airways. Awake fibreoptic intubation is indicated when >2 predictors of difficult intubation AND difficult mask ventilation present, or when airway pathology threatens obstruction. Indigenous patients may have higher rates of obesity, OSA, and limited neck mobility from arthritis, requiring thorough assessment and planning for awake techniques when multiple risk factors present. [1-10]