Investigations

Most children with croup do not warrant any investigations. Viral diagnosis on nasal secretions, usually obtained by per nasal aspiration, can be helpful from an epidemiological point of view but will not alter management. Chest X rays are not helpful for children with typical croup.

Children less than 6 months old who present with croup or those whose croup runs an atypical course warrant investigation. The most useful investigations are likely to be a lateral neck X ray and flexible bronchoscopy.

Management

The majority of children with croup do not require any treatment. Symptomatic treatment for fever and cold symptoms may be warranted. Children with a croupy cough and stridor on exertion (but not at rest) can usually be managed with supportive treatment only. There is a widespread belief that exposing these children to steam, especially by steaming up the home bathroom, helps relieve stridor. There is no evidence to support this treatment. The only benefit that is likely to come from sitting with the child in a steamy bathroom is from sitting quietly with the child and not from the steam. Children with stridor at rest warrant medical assessment. The most useful treatment for croup that has reached this severity is corticosteroids. These can be give orally in syrup form or inhaled (nebuliser or metered dose inhaler and spacer). The mechanism of action is not known but is likely to be via a topical action. A single dose of steroids decreases the risk of hospitalization dramatically.

More severe obstruction can be relieved by nebulised adrenaline. This is usually give as a 50:50 mix of the L- and D-isoforms (known as racemic adrenaline). This relieves obstruction by causing a topical vasoconstriction, which wears off in 1-4 hours, depending on the severity of the underlying obstruction. Severe obstruction may require intubation or even tracheostomy, although the need for these types of treatment have become much less with the widespread use of oral corticosteroids in the emergency departments of paediatric hospitals in Australia.

Recurrent (spasmodic) croup

Some children suffer recurrent episodes of croup, frequently without the preceding viral prodrome usually seen in acute viral croup. Typically these children are well when they go to bed and wake in the early hours of the morning with a barking cough and stridor. Fever is unusual in this form of croup. The same viruses as found in acute viral croup may be found in the upper airways of children with spasmodic croup, although the relationship between the viruses and the symptoms is less clear. Frequently children with recurrent croup have a family history of atopy and asthma or have asthma themselves.

This, together with the uncertain relationship between the clinical symptoms and the presence of a virus, have led to the concept that spasmodic croup maybe a manifestation of upper airway hyperresponsiveness. There are no direct data to support or refute this hypothesis. Spasmodic croup may be severe enough to require treatment with oral corticosteroids, nebulised adrenaline or even intubation; however, the episodes are frequently short lived and often settle by the time the child presents to the emergency department. While controlled trials have not been carried out, there is a substantial body of anecdotal evidence that frequent bouts of recurrent croup can be prevented by maintenance therapy with inhaled corticosteroids via a spacer.