Croup

Girish D. Sharma, MD, FCCP

Introduction/Etiology/Epidemiology

•Croup, or acute laryngotracheobronchitis, is a viral syndrome characterized by acute upper airway obstruction due to swelling of the subglottic area that results in the sudden onset of barky cough, inspiratory stridor, hoarse voice, and respiratory distress.

•Croup is the most common cause of infective upper-airway obstruction in the pediatric age group.

•Croup is usually seen in the preschool age group, with a peak incidence between 18 and 24 months (age range, 6 months to 6 years).

•A male predominance is seen in younger children.

•Viral croup is most commonly caused by parainfluenza virus (PIV) type 1, although PIV types 2 and 3 are responsible for sporadic cases.

•Other viruses implicated in the etiologic origin are influenza A and B, adenovirus, respiratory syncytial virus, rhinovirus, measles, human metapneumovirus, coronavirus, and enteroviruses.

•Epidemics in the fall and winter are commonly caused by PIV type 1; other viruses (eg, PIV type 2) are responsible for sporadic cases.

•Spasmodic croup is a recurrent condition with clinical manifestations similar to viral croup but without prodromal upper respiratory infection symptoms.

Clinical Features

•Frequently, there is a history of mild respiratory infection in the form of coryza, pharyngitis, and low-grade fever prior to the onset of croup.

•There is abrupt onset of characteristic barky cough, respiratory distress, stridor, and hoarse voice.

•Respiratory distress and inspiratory stridor, in a mild case, are usually absent at rest but present when the child is agitated.

•Usually, the onset of symptoms occurs during the early hours of the morning; these symptoms are worse during the evening or at night.

•The symptoms are usually short lived, and most children have resolution of barky cough within 48 hours.

•Symptoms of spasmodic croup are more transient than those of viral croup, they respond differently to therapeutic interventions, and they improve after exposure to cold night air. Warm, humid air, such as that in the shower, may also alleviate the symptoms.

•