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Difficult airway evaluation

Evaluating the Difficult Airway:

Between 13% of patients who require endotracheal intubation have airways that make
intubation difficult. Recognizing those patients who may have a difficult airway allows
the paramedic to proceed with caution and to keep as many options open as possible. It
also allows the paramedic to prepare additional equipment that may not ordinarily be
part of a standard airway kit. The pneumonic LEMON is useful in evaluating patients
for signs that may be consistent with a difficult airway and should raise the paramedic's
index of suspicion.


Look Externally: External indicators of either difficult intubation or difficult
ventilation include - presence of a beard or moustache, abnormal facial shape,
edentulous mouth, facial trauma, obesity, large front teeth or "buck teeth", high arching
palate, receding mandible, or short bull neck.

Evaluate 3-3-2
Rule: 3 fingers between patient's teeth (patient's mouth should open
adequately to permit three fingers to be placed between 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: The scoring system is based on the work of Mallampati et al published in
the Canadian Anesthesia Society Journal in 1985. The system takes into account the
anatomy of the mouth and the view of various anatomical structures when the patient
opens his mouth as wide as possible. The test is performed with the patient n the sitting
position, the head held in a neutral position, the mouth wide open, and the tongue
protruding to the maximum. Inappropriate scoring may occur if the patient is in the
supine position (instead of sitting), if the patient phonates, or if the patient arches his

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

Neck Mobility: Ask the patient to place their chin on their chest and to tilt their head
backward as far as possible. Obviously this will not be possible in the immobilized

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