Understanding Anesthesiology - The Global Regional Anesthesia ...

• Mouth opening: Three fingerbreadths is considered
adequate mouth opening. At this point in the exam,
the anesthesiologist also observes the teeth for overbite,
poor condition and the presence of dental prosthetics.
• Neck motion: The patient touches his chin to his
chest and then looks up as far as possible. Normal
range of motion is between 90 and 165 degrees.
• Adequate space: Ability to visualize the glottis is related
to the size of the tongue relative to the size of
the oral cavity as a large tongue can overshadow the
larynx. The Mallampati classification (Table 2, Figure
4) assigns a score based on the structures visualized
when the patient is sitting upright, with the
head in a neutral position and the tongue protruding
maximally. Class 1 corresponds well with an easy intubation.
Class 4 corresponds well with a difficult intubation.
Classes 2 and 3 less reliably predict ease of
intubation. The thyromental distance is also an important
indicator. The distance from the lower border
of the mandible to the thyroid notch with the neck
fully extended should be at least three to four fingerbreadths.
A shorter distance may indicate that the
oral-pharyngeal-laryngeal axis will be too acute to
Figure 4 Mallampati classification
Table 2 Mallampati Classification
Class 1
Class 2
Class 3
Class 4
Soft palate, uvula, tonsillar
pillars can be seen.
As above except tonsillar
pillars not seen.
Only base of uvula is seen.
Only tongue and hard palate
can be seen.
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