History

A history of difficult airway management in the past may be the best predictor of a challenging airway. Prior anesthetic records should be reviewed for the ease of intubation and ventilation (the ability to mask ventilate and whether adjuncts to mask ventilation were required, the number of intubation attempts, the type of laryngoscope blade used, the size of the endotracheal tube [ETT], or if any specialty airway equipment, ie, video laryngoscopy or a bronchoscope were required). Particular importance should also be placed on diseases that may affect the airway. Specific symptoms related to airway compromise should be sought, including hoarseness, stridor, wheezing, dysphagia, dyspnea, and positional airway obstruction.

1. Arthritis or cervical disk disease may decrease neck mobility. Cervical spine instability and limitation of mandibular motion are common in rheumatoid arthritis. The temporomandibular and cricoarytenoid joints may also be involved. Aggressive neck manipulation in these patients may lead to atlantoaxial subluxation and spinal cord injury. The risk of atlantoaxial subluxation is highest in patients with severe hand deformities and skin nodules.
2. Infections of the floor of the mouth, salivary glands, tonsils, or pharynx may cause pain, edema, and trismus with limited mouth opening. Epiglottitis is a bacterial infection that causes an acute inflammation of the epiglottis and adjacent structures and can result in airway compromise. Because of routine vaccination against Haemophilus, epiglottitis has become more common in adults than children. In patients with airway compromise, intubation should be performed in the operating room with a specialist capable of performing rigid bronchoscopy or surgical airway, if needed, on standby.
3. Tumors may obstruct the airway or cause extrinsic compression and tracheal deviation.
4. Increased body mass index (BMI > 35) coupled with other anatomical findings (high Mallampati score, increased neck circumference, short thyromental distance) can be predictive for difficult mask ventilation and difficult tracheal intubation. The decreased functional residual capacity associated with an increased BMI can result in a precipitous oxygen desaturation with the apnea of induction.
5. A history of snoring or obstructive sleep apnea may be associated with difficult intubation.
6. Trauma may be associated with airway injuries, cervical spine injury, basilar skull fracture, or intracranial injury.
7. Previous surgery, radiation, or burns may produce scarring, contracture resulting in limited tissue mobility, and/or narrowed oral aperture.
8. The physiologic changes associated with pregnancy results in edema of the laryngeal and oral mucosa that can make obtaining a view of the glottis challenging, particularly at the end of the third trimester.
9. Acromegaly may cause mandibular hypertrophy and overgrowth and enlargement of the tongue and epiglottis. The glottic opening may be narrowed because of enlargement of the vocal cords.
10. Scleroderma may produce skin tightness and decrease mandibular motion and narrow the oral aperture.
11. Trisomy 21 patients may have atlantoaxial instability and macroglossia.
12. Osteogenesis imperfecta and achondroplasia may be associated with atlantoaxial instability and potentially difficult airway management because of mandibular hypoplasia (micrognathia).
13. Other congenital anomalies may complicate airway management, particularly pediatric and adult patients with craniofacial abnormalities such as Pierre Robin, Treacher Collins, Klippel-Feil, and Goldenhar syndromes. In contrast, children with isolated cleft palates are not specifically difficult to intubate if the condition is not associated with other airway or craniofacial abnormalities, but nasotracheal intubation should be avoided.