Acute Larynotracheitis (Viral Croup)

Acute laryngotracheitis is the most common cause of acute stridor that is encountered in pediatric practice. It usually occurs in the late fall and winter months, when viral respiratory infections reach their peak incidence. It is more common in boys than in girls, and occurs more often in children between 6 months and 6 years of age who have had an upper respiratory infection for 2 to 3 days before inspiratory stridor develops.

Clinical Features:
Fever usually is present, but the child generally does not appear to be very ill. On cautious examination of the posterior pharynx, the epiglottis may be slightly red and mildly edematous, which is quite different from the gross swelling of acute epiglottitis. The obstruction in acute laryngotracheobronchitis is primarily subglottic in location

Etiology:
Parainfluenza type 1 viruses are the most common cause of viral croups, accounting for up to 65% of the incidents, and parainfluenza type 3, influenza A and B viruses, adenoviruses, respiratory syncytial virus, and echovirus cause most of the rest. Mycoplasma pneumoniae also can produce croup symptoms in older children.

Management:
Most children with croup do not require hospitalization. Treatment at home consists of air humidification, avoidance of agitation, and reduction of fever

If signs of severe obstruction develop, treatment with
an aerosol of racemic epinephrine (2.25%), nebulized with 100% oxygen, frequently provides relief. Frequent aerosol treatments may be needed for the first few hours. A single parenteral dose of dexamethasone, 0.6 mg/kg, is effective in decreasing the length and severity of respiratory symptoms that are associated with viral croup. Inhaled corticosteroid therapy has also been used with some success, but parenteral dexamethasone is somewhat easier. Intubation or tracheostomy rarely is necessary.

Differential Diagnosis:
The differential diagnosis of viral croup includes epiglottitis, foreign body, and angioneurotic edema. Careful history taking usually can distinguish viral croup from these other disorders. Some children have recurrent croup, usually as a result of recurrent infection with viruses that are known to cause the disease. In these patients, however, other congenital and acquired causes of stridor should be considered, especially with infants