A 4-month-old boy is brought by his parents to see his GP due to a history of fever, cough and breathing difficulties. A diagnosis of acute bronchiolitis is made.

  1. What is bronchiolitis?
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Bronchiolitis is an acute infection of the lower respiratory tract that is most commonly seen in infants between the ages of 2 and 6 months. It is usually caused by a viral infection and respiratory syncytial virus (RSV) is the most common causative organism.

The peak incidence of RSV infections is in the winter months between November and March. Bronchiolitis is the most common cause of hospitalisation in infants in the UK.

  1. What are the typical clinical features of bronchiolitis?
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The typical clinical features of bronchiolitis are:

  • Fever
  • Breathing difficulties
  • Cough
  • Poor feeding
  • Irritability
  • Apnoeas (usually in the very young)
  • Wheeze and/or fine inspiratory crackles


  1. How can the diagnosis be confirmed?
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The diagnosis can be confirmed with nasopharyngeal aspirate for RSV rapid testing. This can be helpful to prevent further, unnecessary testing and to enable isolation of the infant.

  1. What are the indications for referral to hospital?
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Most infants with acute bronchiolitis will have a mild, self-limiting illness and will not require hospital admission. Supportive measures are the mainstay of treatment, with attention to good fluid and nutritional intake and temperature control. The illness generally lasts 7-10 days.

Hospital referral and admission is recommended when there is:

  • Poor feeding (<50% of usual intake over past 24 hours)
  • Lethargy
  • History of apnoea
  • Respiratory rate >70 breaths/minute
  • Nasal flaring or grunting
  • Severe chest wall recession
  • Cyanosis
  • Oxygen saturations <94%


If hospitalisation is required then treatment is with supportive measures, supplemental oxygen, and nasogastric feeding as required. There is little or no evidence to support the use of antibiotics, antivirals, bronchodilators, corticosteroids, hypertonic saline or racemic adrenaline nebulisers.


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