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Difficult Airway Assessment Guide

Evaluating for Difficulty of the Airway

It is estimated that between 1 and 3% of the patients who need endotracheal intubation there exists airway problems that makes this procedure difficult.  Recognition of these difficult airways allows the paramedic to proceed with caution and consider other options for airway maintenance.  It affords the paramedic the time for equipment preparation such as the cricothyrotomy kit, which is not part of the normal airway security procedure.  The pneumonic LEMON is useful in the evaluation of a patient prior to endotracheal intubation and may identify some of the potential problems for the endotracheal intubation.

Look Externally

External indicators of either difficult intubation or difficult ventilation include: presence of a beard or moustache, abnormal facial shape, extreme malnourishment, a person without teeth, facial trauma, obesity, large front teeth or “buck teeth”, high arching palate, receding mandible, and/or a short bull neck.

Evaluate 3-3-2 Rule

3 fingers between the patient’s teeth (patient’s mouth should be opened adequately to allow for the placement of three fingers between the upper and lower teeth)

            3 fingers between the tip of the jaw and the beginning of the neck (under the chin)

            2 fingers between the thyroid notch and the floor of the mandible (top of the neck)

Mallampati Scale

This scoring system was first introduced in 1985 in the Canadian Anesthesia Society Journal based on the work of Mallampati.  Place the patient in a seated position and have them hold head in a neutral position with mouth open wide and the tongue fully extended.  The paramedic should visualize on of the following classifications:

Class I (easy)—visualization of the soft palate, fauces, uvula, and both anterior and posterior pillars

Class II—visualization of the soft palate, fauces, and uvula

Class III—visualization of the soft palate and the base of the uvula

Class IV (difficult)—the soft palate is not visible at all

Obstruction

Besides the obvious difficulty if the airway is obstructed with a foreign body, the paramedic should also consider other obstructions such as tumor, abscess, epiglottis, or expanding hematoma.

Neck Mobility

Ask the patient to place their chin on their chest and tilt head backwards as far as possible.  Obviously, this will not be possible in the presence of a trauma patient.