Upper airway obstruction (UAO), which is defined as blockage of any part of the airway located above the thoracic inlet, ranges from nasal obstruction due to the common cold to life-threatening obstruction of the larynx orupper trachea (subglottic space). In children, nasal obstruction is usually more of a nuisance than a danger becausethe mouth can serve as an airway, but it may be a serious problem for neonates, who breathe predominantly throughtheir noses. The differential diagnosis of airway obstruction varies with patient age and can also be subdivided intosupraglottic, glottic, and subglottic causes (Tables 135-1, 135-2, and 135-3).
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UAO is more pronounced during inspiration because the negative pressure generated collapses the upper airway, increasing resistance to airflow and leading to inspiratory noise.The respiratory noise most commonly associated with UAOis stridor, a harsh sound caused by the vibration of the airway structures. Stridor often decreases during sleep, becauseof lower inspiratory flow rates, and increases during feeding,excitement, and agitation, because of higher flow rates. Occasionally stridor may also be present on exhalation. Laryngomalacia (floppy larynx) is the most common cause ofinspiratory stridor in infants and may be aggravated by swallowing problems and gastroesophageal reflux. Hoarseness suggests vocal cord involvement. Children with UAO mayhave increased inspiratory work of breathing manifested bysuprasternal retractions.
Choanal atresia Micrognathia (Pierre Robin syndrome, Treacher Collins syndrome, DiGeorge syndrome) Macroglossia (Beckwith-Wiedemann syndrome, hypothyroidism, Pompe disease, trisomy 21, hemangioma) Pharyngeal collapse Laryngeal web, cleft, atresia Vocal cord paralysis/paresis (weak cry; unilateral or bilateral, with or without increased intracranial pressure from Arnold-Chiari malformation or other central nervous system pathology) Congenital subglottic stenosis Nasal encephalocele
Laryngomalacia (most common non-infectious etiology) Viral croup (most common infectious etiology) Subglottic stenosis (congenital or acquired, e.g., after intubation) Laryngeal web or cyst Laryngeal papillomatosis Vascular rings/slings Airway hemangioma Rhinitis
Viral croup (most common etiology in children 6 mo to 4 yr of age) Spasmodic/recurrent croup Bacterial tracheitis (toxic, high fever) Foreign body (airway or esophageal) Laryngeal papillomatosis Retropharyngeal abscess Hypertrophied tonsils and adenoids
Epiglottitis (infection, uncommon) Inhalation injury (burns, toxic gas, hydrocarbons) Foreign bodies Angioedema (familial history, cutaneous angioedema) Anaphylaxis (allergic history, wheezing, hypotension) Trauma (tracheal or laryngeal fracture) Peritonsillar abscess (adolescents) Mononucleosis Ludwig angina