How is the anticipated difficult intubation approached?
Anticipated difficult intubations with proven
or sus-pected difficult mask ventilation are best approached with the patient
awake and spontaneously breathing. Proper preparation of the airway before
instrumentation is criti-cal. Preparation begins approximately 1 hour before arrival
in the operating room. At that time, antisialagogues are administered as
premedication. Their use is intended to desiccate the mucosa before
administration of topical local anesthetics. An intervening layer of secretions
acts as a physical barrier preventing contact between local anesthetic and
mucosa. Without direct contact of the two, inadequate airway anesthesia results
and predisposes the patient to coughing, gagging, and withdrawal. Furthermore,
copious secretions impair the view through flexible fiberoptic laryngoscopes.
Depending on the degree of pre-existing airway compromise, preoperative
sedation may be contraindicated.
After adequate antisialagogue effect, airway
anesthesia is most easily achieved by nebulizing 4 mL of 4% lidocaine. Another
equally effective option is to atomize the same solution. Superior laryngeal
nerve blocks and transtracheal nerve blocks are sometimes required.
If the nasal approach is planned, the risk of
epistaxis can be minimized with topical application of 0.5% phenyle-phrine, 4%
cocaine, or 0.05% oxymetazoline (Afrin). In the absence of local nasal
pathology, flexible fiberoptic nasal tracheal intubation is generally less
difficult than the oral route.
After achieving satisfactory airway anesthesia,
most intubation techniques progress well to successful comple-tion. Blind
techniques, retraction blades, or fiberscopes are commonly employed.
Friable tumors, abscesses, and impending
obstructive airway tumors often require awake tracheostomy.
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