Croup

Microbiology

Croup is a form of upper respiratory tract infection seen in infants and toddlers. It is characterised by stridor which is caused by a combination of laryngeal oedema and secretions. Parainfluenza viruses account for the majority of cases.

Epidemiology

peak incidence at 6 months - 3 years
more common in autumn

Features

stridor
barking cough (worse at night)
fever
coryzal symptoms

Clinical Knowledge Summaries (CKS) suggest using the following criteria to grade the severity*:

Mild	Moderate	Severe
Occasional barking cough No audible stridor at rest No or mild suprasternal and/or intercostal recession The child is happy and is prepared to eat, drink, and play	Frequent barking cough Easily audible stridor at rest Suprasternal and sternal wall retraction at rest No or little distress or agitation The child can be placated and is interested in its surroundings	Frequent barking cough Prominent inspiratory (and occasionally, expiratory) stridor at rest Marked sternal wall retractions Significant distress and agitation, or lethargy or restlessness (a sign of hypoxaemia) Tachycardia occurs with more severe obstructive symptoms and hypoxaemia

CKS suggest admitting any child with moderate or severe croup. Other features which should prompt admission include:

< 6 months of age
known upper airway abnormalities (e.g. Laryngomalacia, Down's syndrome)
uncertainty about diagnosis (important differentials include acute epiglottitis, bacterial tracheitis, peritonsillar abscess and foreign body inhalation)

Management

CKS recommend giving a single dose of oral dexamethasone (0.15mg/kg) to all children regardless of severity
prednisolone is an alternative if dexamethasone is not available

Emergency treatment

high-flow oxygen
nebulised adrenaline

*these in turn are based partly on the Alberta Medical Association (2008) Guideline for the diagnosis and management of croup.