Aetiology

Asthma may occur at any age but is most common among children and young adults. Several factors may precipitate an acute asthma attack and these are sometimes considered as either extrinsic or intrinsic:

extrinsic

– inhaled external antigens, e.g. dusts

intrinsic

– exercise

– anxiety

– cold air

– infection, e.g. viral bronchitis.

While atopic asthma is the most common form of extrinsic asthma, other forms include occupational asthma and allergic bronchopulmonary aspergillosis; the latter is an IgE-mediated allergic reaction to Aspergillus colonization of the airways.

Clinical presentation

Breathlessness and wheezing are the dominant symptoms while examination may reveal an overexpanded chest and confirm the presence of wheezes on stethoscope examination (auscultation). Lung function testing reveals an obstructive pattern of defect (Fig. 3.44.2). Asthma attacks vary in severity, with severe attacks requiring hospital treatment. The most severe form of asthma attack is termed status asthmaticus and this can lead to respiratory failure and death unless prompt treatment is given.