Airway assessment is the first step in successful airway management. Several anatomical and func-tional maneuvers can be performed to estimate the difficulty of endotracheal intubation; however, it is important to note that successful ventilation (with or without intubation) must be achieved by
the anesthetist if mortality and morbidity are to be avoided. Assessments include:
· Mouth opening: an incisor distance of 3 cm or greater is desirable in an adult.
· Upper lip bite test: the lower teeth are brought in front of the upper teeth. The degree to which this can be done estimates the range of motion of the temperomandibular joints.
· Mallampati classification: a frequently performed test that examines the size of the tongue in relation to the oral cavity. The greater the tongue obstructs the view of the pharyngeal structures, the more difficult intubation may be (Figure 19–5).
o Class I: the entire palatal arch, including the bilateral faucial pillars, are visible down to their bases.
o Class II: the upper part of the faucial pillars and most of the uvula are visible.
o Class III: only the soft and hard palates are visible.
o Class IV: only the hard palate is visible.
· Thyromental distance: the distance between the mentum and the superior thyroid notch. A distance greater than 3 fingerbreadths is desirable.
· Neck circumference: a neck circumference of greater than 27 in is suggestive of difficulties in visualization of the glottic opening.
Although the presence of these findings may not be particularly sensitive for detecting a difficult intubation, the absence of these findings is predic-tive for relative ease of intubation.
Increasingly, patients present with morbid obe-sity and body mass indices of 30 kg/m2 or greater. Although some morbidly obese patients have rela-tively normal head and neck anatomy, others have much redundant pharyngeal tissue and increased neck circumference. Not only may these patients prove to be difficult to intubate, but routine ventilation with bag and mask also may be problematic.
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