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Introduction

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After I'd written to you yesterday I had an attack of asthma and an incessantly running nose, which forced me to tramp about, lighting cigarettes at every tobacconist etc. And worse was to come: I went to bed about midnight, feeling all right after spending a long time inhaling smoke, but 3 or 4 hours later came the real attack of the summer.

Marcel Proust, letter to his mother, 1901

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Asthma is defined by the presence of both of the following:1

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  • excessive variation in lung function (‘variable airflow limitation’ i.e. variation in expiratory airflow that is greater than that seen in healthy people)

  • respiratory symptoms (e.g. wheeze, shortness of breath, cough, chest tightness) that vary over time and may be present or absent at any point in time

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In young children in whom lung function testing is not feasible, including most preschool children, asthma is defined by the presence of variable respiratory symptoms.

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Key facts and checkpoints

  • Asthma continues to be underdiagnosed and undertreated.3 It is increasing worldwide.

  • It has an unacceptable mortality rate of approximately 5 per 100 000 of the population.

  • About one child in four or five has asthma (usually in a mild form).

  • It tends to develop between the ages of 2 and 7 years, but can develop at any age.

  • Most children present with a cough.

  • Most children are free from it by puberty.

  • At least one in seven adolescents has asthma.

  • About one adult in eight has or has had asthma.

  • The focus of management should be on prevention; an acute asthmatic attack represents failed treatment.

  • Measurement of function is vital as ‘objective measurement is superior to subjective measurement’.

  • Spirometry is the key investigation.

  • The earlier steroid therapy is introduced, the better the outcome.

  • Inhaled corticosteroids are the cornerstone of asthma treatment.

  • Avoid concomitant medication that may exacerbate asthma (e.g. beta blockers, aspirin, NSAIDs).

  • New aerosols, notably hydrofluoroalkanes, have non-CFC propellants leading to increased lung deposition and thus requiring overall lower dosage.

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Chronic asthma is an inflammatory disease with the following pathological characteristics:

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  • infiltration of the mucosa with inflammatory cells (especially eosinophils) and cellular elements

  • airway hyper-responsiveness2

  • intermittent airway narrowing (due to bronchoconstriction, congestion or oedema of bronchial mucosa or a combination of these) (see FIG. 82.1)

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FIGURE 82.1

Airway changes in asthma: (a) normal airway, (b) airway in asthma

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Causes of asthma

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No single cause for asthma has been found, but a variety of factors may trigger an attack. These include specific factors such as viruses, allergens and non-specific factors such as temperature or weather changes and exercise. A checklist of trigger factors includes:

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  1. allergens—pollens, animal dander, dust mites, ...

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