CROUP

Croup is a clinical syndrome characterized by a seal-like barking cough, hoarseness, inspiratory stridor, and often some degree of respiratory distress. The term croup is usually used to refer to acute laryngotracheobronchitis. Other crouplike syndromes can include spasmodic croup and bacterial tracheitis (Table 29.1). Other potential infectious causes of stridor include supraglottitis (epiglottitis), peritonsillar abscess, retropharyngeal abscess, and rarely diphtheria, whereas noninfectious etiologies include angioneurotic edema, foreign body obstruction, hemangioma, trauma, neoplasm, subglottic stenosis, or extrinsic compression. Croup is primarily a disease of children between the ages of 1 to 6 with peak incidence between 6 months and 3 years. The parainfluenza viruses (1, 2, and 3) are the most frequent cause with outbreaks occurring predominantly in the winter months. Other occasional causes include respiratory syncytial virus (RSV), influenza, and adenovirus with rare cases secondary to Mycoplasma, Corynebacterium diphtheriae, and herpes simplex virus (HSV). In adults, the causes are also predominantly viral, including reported cases of influenza, parainfluenza, RSV, HSV, and cytomegalovirus (CMV). In either children or adults, most likely secondary bacterial infections with Haemophilus influenzae type b (Hib), staphylococci, Moraxella catarrhalis, and Streptococcus pneumoniae can be seen.

Croup usually follows a relatively mild upper respiratory infection. Its onset is commonly abrupt and occurs in the late evening and night. Viral infection with associated inflammation of the nasopharynx spreads inferiorly to the respiratory epithelium of the larynx and trachea.