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    Difficult Airway Identification in the Emergency Department

    Critical Care / Resuscitation, Respiratory

    Last Updated Oct 31, 2018
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    Note: for management see: Difficult Airway Management

    • Resuscitative airway management in the emergency department (ED) in the adult population (>16 years of age) is a relatively rare but complex and challenging scenario that includes overdose, trauma, sepsis, airway obstruction, respiratory failure amongst others.
    • By definition, the difficult airway includes difficulty with:
      • Bag mask ventilation (BMV; oxygenation and ventilation);
      • Supraglottic device ventilation/oxygenation; and/or
      • Laryngoscopy and intubation
    • It is reasonable to assume that every ED airway intervention is difficult until proven otherwise and to be generally prepared for a difficult airway challenge.
    • It is possible to predict a difficult airway and to risk stratify patients undergoing procedural sedation who may need airway management during the sedation intervention.
    • However, no difficult airway prediction tool is robust and all have suboptimal test characteristics; be prepared!


    The Difficult Airway in the ED may be inferred by asking three questions:

    1. Is the patient potentially difficult to BMV?
    • Predicts whether pre-oxygenation or rescue oxygenation will be easy or difficult.
    • Any positive component of “BOOTS” (“bearded, older, obese, toothless and/or snoring”) independently predicts potential difficulty with BMV.


    1. Is the patient potentially difficult to intubate?
    • MMAP”: Mallampati class, Measurement (“3-3-1 rule”), Atlanto-occipital extension, Pathology

    Mallampati classification (Class 1 to IV), with mouth opening and extruding tongue in a cooperative patient without phonation is a predictor of difficulty of intubation (Roughly Class 1 = “easy” and Class IV = “difficult). Atlanto-occipital extension: In the absence of Cspine precautions, the patient’s ability to flex the neck at the cervico-thoracic junction and extend the head at the atlanto-axial junction is a predictor of intubation. Pathology means pathologic processes at the periglottic inlet/area including both medical pathology (angioedema, infection, tumors etc) or trauma pathology (blunt or penetrating) and predicts potential considerable difficulty with intubation.

    • (Other mnemonics exist such as “LEMON”: Look externally, Evaluate 3-3-2 rule, Mallampati score, Obstruction, Neck Mobility).


    1. Is the patient potentially difficult to “rescue” with a supraglottic device or difficult to perform a surgical airway on?

    The associated mnemonic for difficult “rescue” question (with supraglottic device) is:  RODSRestricted mouth opening, Obstruction, Distorted airway, Stiff lungs or c-spine.

    The associated mnemonic for predicting a difficult surgical airway = SHORTSurgery, Hematoma, Obesity, Radiation distortion or other deformity, Tumor.


    Difficult Airway Algorithm

    Created By Ella Barrett-Chan, MSI UBC


    Quality Of Evidence?


    General consensus by airway experts and low-level papers and with predictors possessing low specificity and low positive predictive value.

    Ref example: Crosby ET, Cooper RM, Douglas, et al. The unanticipated difficult airway with recommendations for management. Can J Anaesth. 1998 Aug;45(8):757-76.


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