A careful medical history is essential in the evaluation of upper airway obstruction and helps to categorize the nature of the obstruction. The predominant symptoms of airway dysfunction elicited during a careful history interview are stridor, sturdor, dyspnea, cough, aspiration, hoarseness, and dysphagia and odynophagia. Depending on the degree of upper airway obstruction and ability of the patient to compensate, the signs and symptoms may vary from severe stridor with air hunger to mild sturdor.

The character of noisy breathing in relation to the respiratory cycle helps localize the site of obstruction. When the obstruction is supraglottic or oropharyngeal, muffled, rattling, noisy breathing (sturdor) occurs and may be partly relieved when the tongue is pulled forward. Supraglottic obstruction produces inspiratory stridor. Glottic obstruction also tends to produce inspiratory stridor, but usually with a hoarse or breathy voice. However, a normal voice may still be present if the vocal cords remain in a median position due to bilateral vocal cord paralysis. Subglottic obstruction produces inspiratory and expiratory stridor. Intrathoracic obstruction produces expiratory wheezing.

The onset, frequency, duration of noisy breathing and the presence of cyanosis should be determined. Associations with feeding, agitation, exercise, sleep, and position changes should be
sought. For instance, a child with feeding difficulties, prolonged feeding times, or regurgitation with stridor that worsens in the supine position is likely to have gastroesophageal reflux disease. The degree of dyspnea and anxiety helps determine the acuity of the obstruction. A cough is pathologic when it increases in frequency or is associated with production of secretions. Hoarseness is more ominous when it is progressive rather than intermittent.