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Croup
Croup

Croup

Croup, also known as laryngotracheobronchitis, is a common childhood upper respiratory tract infection with a characteristic seal-like barking cough.

🏘️ Epidemiology

It most commonly affects children aged 6 months - 3 years old (highest incidence at 2 years old).

Boys are slightly more affected than girls (1.4:1).

It is more common in late autumn but there are cases throughout the entire year.

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🦠 Pathophysiology and causative agents

It is a viral infection typically caused by:

  • ⭐️ Parainfluenza viruse type 1 and type 3 - this is by far the most common causative agent.
  • Influenza A and B
  • RSV
  • Adenovirus
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Diphtheria is a rare bacterial cause of croup, however, it is important to consider as if left untreated it may progress to epiglottitis.

Infection leads to inflammation and oedema of the airways → upper airway obstruction. This narrows the subglottic region (just below the larynx) which causes stridor and a seal-like barky cough. If the obstruction worsens, it can lead to respiratory failure.

🔢 Classification

We can classify it according to its severity, ranging from mild → impending respiratory failure.

  1. Mild - seal-like barky cough, no stridor, no suprasternal/intercostal recession. Child is comfortable.
  2. Moderate - seal-like barky cough, audible stridor, suprasternal/intercostal recession, no distress or agitation.
  3. Severe - seal-like barky cough, audible stridor, suprasternal/intercostal recession, agitation and lethargy.
  4. Impending respiratory failure - seal-like barky cough, audible stridor, suprasternal/intercostal recession, agitation and lethargy, asynchronous chest wall and abdominal movement, hypoxia and hypercapnia, tachycardia.

😷 Presentation

Symptoms are typically worse at night and agitation increases with the severity of the symptoms.

  • Barking cough
  • Stridor
  • Hoarse voice
  • Fever
  • Coryzal symptoms - rhinorrhoea, sneezing.
  • Lethargy
  • Respiratory distress - costal recession and asynchronous breathing movements may be present in progressed disease. Cyanosis will indicate impending respiratory failure.

🔍 Investigations

It can be diagnosed clinically with a history and examination. Testing is not particularly useful in making a diagnosis. It is important to not frighten the child when examining them as it can worsen symptoms.

A CXR need not be done but if it is done we may see the typical steeple sign on the PA view.

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🧰 Management

  • Most cases can be dealt with in primary care with a single dose of dexamethasone (0.15mg/kg).
  • Severe cases will need hospital admission.
    • While waiting for admission, we should give:
    • Supplementary oxygen + nebulised budesonide OR IM dexamethasone (if we are not able to give oral dexamethasone).
  • If there is significant concern or emergency treatment is needed, nebulised adrenaline may also be given along with high-flow oxygen.