If diphtheria is the cause, respiratory distress with airway compromise is quite marked secondary to the pseudomembrane blocking the laryngeal inlet . Complete obstruction and respiratory arrest may occur. Fortunately, immunization for diphtheria in the United States has made this disease extremely rare. Diagnosis is made by history and physical examination. The physical examination may show some minor erythema and minimal edema of the supraglottic structures.
Treatment includes resting the voice and inhalation of humidified air.
Antibiotics are indicated if diphtheria is thought to be the cause. Children who present to the physician with the typical signs and symptoms of croup should be treated as if they have typical croup. But, if the child presents with atypical features of croup, such as recurrent episodes or a persistent episode despite adequate treatment, other causes must be sought. These include laryngeal or tracheal anomalies like congenital subglottic stenosis, webs, or cysts. If the child is younger than 12 months of age, these underlying causes must also be considered because, although croup can present as early as 3 months of age, it is more likely to occur in children over twelve months.