Physical findings	Possible etiology
General
Cyanosis	Cardiac disorder, hypoventilation with hypoxia
Fever	Underlying infection
Toxicity	Epiglottitis
Tachycardia	Cardiac failure
Bradycardia	Hypothyroidism
Quality of stridor
Inspiratory stridor	Obstruction above glottis
Expiratory stridor	Obstruction at or below lower trachea
Biphasic stridor	Glottic or subglottic lesion12
Position of the child
Hyperextension of the neck	Extrinsic obstruction at or above larynx13
Leaning over, drooling	Epiglottitis
Lessening of stridor in prone position	Laryngomalacia
Chest findings
Prolonged inspiratory phase	Laryngeal obstruction
Prolonged expiratory phase	Tracheal obstruction
Unilateral decreased air entry	Foreign body in ipsilateral bronchus
Associated signs
Arrhythmias, significant heart murmurs, abnormal heart sounds	Structural heart disease
Cutaneous hemangiomas	Subglottic hemangioma
Peripheral neuropathy	Vocal cord paralysis
Urticaria/angioneurotic edema	Angioneurotic edema