Asthma

See also Acute Asthma Attack

• widespread airway narrowing

• airway obstruction that varies spontaneously or due to treatment

  • increased responsiveness of airway to various stimuli

• not due to cardiovascular disease

Typical Patient

• 1-25% children

• atopic / family history atopy

• children who had severe bronchiolitis as infant may continue to have wheeze not related to atopic state

• occupational exposure - worse 6-8 hours after exposure (often after work)

  • organic dusts

  • fumes

History

• wheezing

• persistent cough worse at night

  • or brought on by irritants - e.g. cold air

Examination

• chest may be overinflated

• signs of chest deformity

  • Harrison sulci

  • pectus carinatum

Differential Diagnosis

• Bronchiolitis

• Other viral respiratory tract infections

• Cystic Fibrosis

• Recurrent inhalation bronchitis

• TB (hilar nodes)

• Foreign body

Pathology

• atopy

  • inherited predisposition to type I  / IgE mediated hypersensitivity

• activation of mast cells and eosinophils

• ongoing inflammation

• epithelial damage and shedding

• bronchospasm

• mucosal swelling

• plugging of airways

Investigations

• home PEFR / spirometry

  • diurnal variation

  • morning dips

  • >15% reversibility

• Skin prick tests

• FBC

  • eosinopilia

• Hyperreactivity

  • methylcholine

  • histamine

Chronic Management

• Assessment

  • PEFR

  • Frequency of inhaler use

  • nocturnal / early morning symptoms

• Strategy

  • avoidance of precipitants

  • education

• British Thoracic Society Guidelines (step up / step down - start at most appropriate step to disease severity)

  1. short-acting b₂-agonist PRN

  2. inhaled steroid 200-800mg

     • starting dose relevant to severity, usual 400mg

  3. steroid + Long-acting b₂-agonist

     • + assessment of control

     • if no response increase steroid or try another drug

  4. increase inhaled steroid to 2000mg

  5. Attempt to minimise need for oral steroids

     • refer to specialist

Treatments

• Beta₂ Agonists

• corticosteroids

  • usually inhaled (80% destroyed by first pass metabolism)

  • use only enough to control asthma, not more

• antimuscarinics

• theophyllines

• sodium chromoglycate (adults) / nedocromil sodium (children)

  • mast cell stabilisers

Prognosis

• mortality 1500 / year (UK)

Complications

• severe acute asthma attack

• death

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