Croup

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management | Patient Advice

Definition

Croup, also known as laryngotracheobronchitis, is a viral respiratory illness that causes inflammation and swelling of the larynx, trachea, and bronchi, leading to airway obstruction. It is most common in children aged 6 months to 3 years.

Aetiology

Croup is caused primarily by viral infections, including:

• Parainfluenza Virus: The most common cause.
• Respiratory Syncytial Virus (RSV): A common cause in younger children.
• Adenovirus: Occasionally implicated.
• Influenza Virus: Associated with more severe cases.

Pathophysiology

The viral infection causes inflammation of the upper airway, leading to:

• Swelling: Narrowing of the subglottic space, which is the narrowest part of the paediatric airway.
• Obstruction: Partial airway blockage causes stridor and barking cough.
• Increased Effort of Breathing: Results from airway resistance and poor airflow.

Risk Factors

Risk factors for developing croup include:

• Age (6 months to 3 years).
• Exposure to respiratory viruses (e.g., in daycare settings).
• Family history of croup or recurrent respiratory illnesses.
• Seasonal occurrence (more common in autumn and winter).

Signs and Symptoms

Common features of croup include:

• Barking Cough: Characteristic "seal-like" cough.
• Stridor: High-pitched inspiratory sound due to airway narrowing.
• Hoarseness: Due to laryngeal inflammation.
• Fever: Low-grade fever is common.
• Respiratory Distress: Increased effort of breathing, including nasal flaring, intercostal recession, and tracheal tug.

Investigations

Croup is primarily a clinical diagnosis, but the following may be helpful in selected cases:

• Clinical Assessment: Diagnosis based on history and characteristic symptoms (barking cough, stridor).
• Pulse Oximetry: To monitor oxygen saturation in moderate to severe cases.

Management

1. Mild Croup

• Supportive Care: Keep the child calm and hydrated.
• Single Dose of Oral Dexamethasone: (0.15 mg/kg) to reduce airway inflammation.

2. Moderate to Severe Croup

• Nebulised Adrenaline: Used in severe cases to reduce airway swelling temporarily.
• Oxygen Therapy: For children with hypoxia (SpO₂ < 92%).
• Oral or Intramuscular Dexamethasone: Higher dose (0.6 mg/kg) for significant airway obstruction.
• Hospital Admission: For children with persistent stridor at rest, respiratory distress, or poor response to initial treatment.

Patient Advice

Key advice for parents includes:

• Keep the child calm, as agitation can worsen symptoms.
• Ensure adequate hydration and monitor for worsening symptoms.
• Seek immediate medical attention if the child develops worsening stridor, difficulty breathing, or cyanosis.
• Reassure parents that croup is usually self-limiting and resolves within 3–7 days.