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Cough - acute with chest signs in children - Background information
What is it?
- Bronchiolitis is a condition predominately of infants less than 12 months of age. It is caused by a viral infection, most commonly respiratory syncytial virus, of the epithelial lining of the lower bronchial tree [SIGN, 2006]. Infected epithelial cells slough off into the small airways and the alveolar spaces. This, together with mucus, causes variable obstruction of the small airways, with complete obstruction and collapse in some, and partial obstruction in others [DeVincenzo, 2007]. These changes result in:
- Impaired gaseous exchange leading to hypoxia and breathlessness.
- Crackles throughout the lung fields and, in some infants, wheeze.
- Viral-induced wheeze is a condition of children between 6 months and 5 years of age who present with wheeze in association with respiratory tract infection. Later respiratory tract infections commonly result in recurrence of wheeze, but the majority of children outgrow their tendency to wheeze by 6 years of age. The mechanism by which infection causes wheeze is complex and not fully understood, but it is known that these children have abnormally small airways which predispose them to wheeze [Wilson, 2003].
- Infective exacerbations of asthma may be difficult to distinguish from viral-induced wheeze in a child of less than 5 years of age. Wheezing occurs due to bronchoconstriction in response to a respiratory tract infection, but may also occur in response to other stimuli (e.g. exercise) and exposure to allergens (e.g. pollen). Wheezing is more common in people with atopy or a family history of atopy [Wilson, 2003].
- Community-acquired pneumonia is an acute infection of the lung parenchyma, acquired in the community, that may be caused by bacteria, atypical bacteria, or viral infections [Bartlett, 2003]. Infection leads to localized collapse and consolidation of the alveolar air spaces resulting in:
- Impaired gaseous exchange, which may cause hypoxia and breathlessness.
- Localized crackles.
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