- History of difficult intubation
- Suspected difficult airway based upon findings in history or physical exam, including but not limited to the following:
- Trauma to the airway
- Deep neck infections
- Tumors of the larynx or pharynx
- History of radiation to the airway
- Severe ankylosing spondylitis
- Acromegaly
- Congenital airway abnormality, such as Treacher-Collins or Pierre Robin Syndromes
- Inability to access the cricothyroid membrane, in case emergency surgical airway is required
- Morbid obesity and history of sleep apnea with suspected difficult airway requiring intubation
- Anatomy that otherwise predisposes patient to difficult intubation and difficult mask ventilation while asleep
- High risk for aspiration of gastric contents
- Need for neurological exam immediately following intubation
- Cervical spine instability due to trauma or degenerative disease
- Vertebrobasilar artery insufficiency
- Absolute contraindications
- Patient refusal
- Allergy to both ester and amide classes of local anesthetics
- Relative contraindications, which may be overlooked in the true emergency situation because the risk of the procedure is less than the risk of hypoxemia or impending loss of the airway
- Infection at sites of local anesthetic injection/application
- Raised intracranial pressure (ICP) that might be exacerbated by coughing
- Penetrating eye trauma that might be exacerbated by coughing
- Flexible fiberoptic bronchoscope and light source
- Suction
- Oxygen source
- Cuffed endotracheal tubes (in several sizes)
- Warm solution, such as saline surgical irrigation, in a 1-L bottle
- Lubricant, such as silicon gel or (less desirable) Surgilube (Fougera, Melville, N.Y.)
- Antifog liquid drops for the fiberoptic camera lens
- Tongue depressor or laryngoscope blade
- Nasal trumpet with 7.0 ETT connector inserted in proximal end
- An antisialagogue, such as glycopyrrolate (0.2 to 0.4 mg in adult patients)
- Local anesthetic, such as lidocaine (viscous 2%, 4%, and 5% paste)
- Phenylephrine (10 mg/mL)
- Sedative hypnotics, such as benzodiazepines or low-dose propofol infusions together with an opiate delivered in small doses (fentanyl or remifentanil), with or without droperidol (not to exceed 2.5 mg in adult patients)
- Right-angle forceps
- Cotton soaked pledgets
- Atomizer or Cetacaine (Cetylite, Pennsauken, N.J.) topical spray
- Williams or Berman intubating oral airway
- Appropriate vital signs monitors
External Anatomic Features
Important external landmarks are the mental protuberance of the mandible, thyroid cartilage, hyoid bone, and cricoid cartilage.
Anatomical features of direct relevance to flexible fiberoptic laryngoscopy include mouth opening, extent of jaw subluxation, ability to flex and extend the neck, neck circumference, tongue size and protrusion, ability to visualize the uvula or soft palate with mouth opened and tongue protruded in the sitting posting without phonation (Mallampati score), mandibular size, mentohyoid distance, thyromental distance, and protuberant dentition.
Internal Anatomy
Mouth
- Examination should include the following:
- Size of the mouth opening, size and distribution of teeth, and size of the tongue play important roles in ease of laryngoscopy and intubation.
- Clear assessment and documentation of dentition with special care given to patients with fragile dentition, including caps; implants; crowns; and loose, missing, or decaying teeth
- Identification and removal of any personal ornamentation, such as tongue piercings, should occur before undertaking airway manipulation, to avoid aspiration of the ornament or trauma and edema in the oropharynx.
Nasal Cavity and Nasopharynx
- On the sides of the nasal cavity are three horizontal protuberances call turbinates or conchae. The nasal cavity is divided in half vertically by the nasal septum.
- The nasopharynx lies behind the nose, above the soft palate, and is bounded posteriorly by the pharyngeal tonsils.
Oropharynx
- Includes the structures of the upper airway from the soft palate to the level of the hyoid bone
- The laryngopharynx includes the epiglottis and larynx, which in turn consists of the vocal folds and vocal cords; the thyroid, cricoid, and arytenoid cartilages; and the intrinsic muscle of the larynx.
- The larynx begins where the upper airway divides to form the laryngeal inlet and the upper esophagus.
- The epiglottis is a cartilaginous flap attached to the posterior tongue, which forms a protective flap between the trachea and the upper esophagus.
Innervation of the Airway
- Innervation to the airway may be divided into nasal and oral, pharyngeal, laryngeal, and tracheal compartments.
- Branches of the trigeminal nerve (cranial nerve V) supply sensation to all parts of the nasal cavity
- In the oral cavity, somatosensory input to the anterior two thirds of the tongue are supplied by the lingual nerve (cranial nerve V3). Somatosensory input to the posterior third of the tongue arises from the glossopharyngeal nerve (cranial nerve IX).
- The glossopharyngeal nerve also supplies sensation to the pharynx, including the fauces and tonsils, epiglottis, and the soft palate.
- Motor supply to the pharynx and larynx is primarily via the vagus nerve (cranial nerve X). Sensory inputs to the glottis and supraglottis arise from the superior laryngeal nerve.
- Motor innervation to all other muscles of the larynx as well as sensory innervation of the subglottis originate from the recurrent laryngeal nerve.
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