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Asthma

Key Points ⚡

  • Asthma: chronic inflammatory airway disease causing episodic symptoms like shortness of breath, cough, and wheeze.
  • Aetiology: involves airway inflammation, smooth muscle hypertrophy, and airway remodelling. Exacerbations often triggered by respiratory viruses, allergens, pollutants, occupational exposure.
  • Risk factors: non-modifiable (genetics, family history, atopy, male sex for development, female sex for persistence), modifiable (smoking, inhaled particulates, obesity, social deprivation, infant infections).
  • Symptoms: episodic wheeze, cough, breathlessness; typically worse at night or early morning.
  • Triggers: pets, carpets, temperature changes, occupational exposures, smoking.
  • Examination: may be normal between attacks; look for increased work of breathing, cyanosis, polyphonic expiratory wheeze.
  • Investigations:
  • PEFR with diurnal variation (>20%)
  • Spirometry: FEV1/FVC <70%, bronchodilator reversibility (FEV1 improvement ≥12% and 200ml)
  • FeNO testing (≥40 ppb adults suggests eosinophilic inflammation)
  • Blood eosinophils, total and specific IgE
  • Chest X-ray to exclude complications
  • Skin prick testing for atopy
  • Bronchial challenge test if diagnosis uncertain
  • Management: multidisciplinary; personalised asthma action plan; smoking cessation; weight loss; vaccination; stepwise inhaler therapy:
  • SABA reliever
  • Add low-dose ICS
  • Add LABA or LTRA
  • Increase ICS dose or trial LTRA
  • High-dose ICS +/- specialist referral
  • Complications: pneumonia, pneumothorax, respiratory failure, status asthmaticus, impaired quality of life, steroid side effects, death.
  • Prognosis: many children with early-onset asthma may outgrow it; males more likely to outgrow than females.

Introduction

  • Asthma is a common chronic respiratory disease characterised by airway inflammation and hyper-responsiveness causing episodic symptoms.
  • Approximately 3 deaths daily in the UK from acute asthma attacks.

Aetiology

  • Chronic inflammation leads to smooth muscle hypertrophy and airway wall thickening.
  • Exacerbations commonly triggered by respiratory viruses; also bacterial infections, allergens, pollutants, occupational factors.

Risk Factors

  • Non-modifiable: family history of atopy, male sex (development), female sex (persistence), prematurity, low birth weight.
  • Modifiable: tobacco smoke exposure, inhaled particulates, obesity, social deprivation, infant infections.

Clinical Features

History

  • Episodic wheeze, cough, breathlessness, worse at night/early morning.
  • Triggers (pets, carpets, temperature, occupation).
  • Exacerbation frequency, hospital/ICU admissions.
  • Smoking history, treatment adherence.

Examination

  • May be normal between attacks.
  • Signs during attack: increased work of breathing, cyanosis, polyphonic expiratory wheeze.

Differential Diagnoses

  • Bronchiectasis
  • COPD
  • Lung cancer
  • Gastro-oesophageal reflux
  • Heart failure
  • Chronic sinusitis
  • Allergic rhinitis
  • Foreign body inhalation
  • Vocal cord dysfunction

Investigations

Bedside

  • PEFR with diurnal variability assessment.

Laboratory

  • WCC, CRP for infection.
  • Eosinophils, total and specific IgE.
  • Sputum MCS if productive cough.

Imaging

  • Chest X-ray to exclude complications or alternate diagnoses.

Pulmonary Function Tests

  • Spirometry with bronchodilator reversibility (FEV1/FVC <70%, FEV1 improvement ≥12% and 200ml).
  • FeNO testing to detect eosinophilic inflammation (≥40 ppb adults).
  • Bronchial challenge test if diagnostic uncertainty persists.

Diagnosis

  • Based on clinical history, examination, and investigations.
  • Treatment trial and monitoring often required to confirm diagnosis.

Management

General

  • Multidisciplinary approach involving patients, asthma nurses, GPs, respiratory physicians, physiotherapists.
  • Personalised asthma action plan with daily management and exacerbation guidance.
  • Annual asthma reviews assessing control, adherence, inhaler technique, smoking status, PEFR, vaccinations.
  • Lifestyle modifications: smoking cessation, weight loss, referrals as needed.

Pharmacological

  • Stepwise escalation to achieve symptom control with minimal side effects.
  • Mainstay: inhalers (SABA, ICS, LABA), with leukotriene receptor antagonists (LTRA) or biologics as adjuncts under specialist care.

Complications

  • Pneumonia, pneumothorax, respiratory failure, status asthmaticus.
  • Reduced quality of life in uncontrolled asthma.
  • Steroid side effects.
  • Death in severe cases.

Prognosis

  • Many children, especially males with early-onset asthma, may outgrow it by adulthood.

References

  • NICE Asthma Guidelines 2021
  • Asthma UK Facts and Statistics 2017
  • Thorax 2006: Asthma Exacerbations - Aetiology
  • British Thoracic Society SIGN Guidelines 2019
  • Bronchiectasis
  • Chronic Obstructive Pulmonary Disease (COPD)
  • Croup
  • Cystic Fibrosis
  • Interstitial Lung Disease