Introduction

Asthma is a chronic respiratory condition characterised by airway inflammation, bronchial hyperresponsiveness, and variable airflow obstruction. Understanding asthma’s pathophysiology, triggers, and management guidelines is essential for optimising patient care and improving outcomes.

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Pathophysiology

1. Airway Hyperresponsiveness

   • Hallmark feature of asthma.
   • Exaggerated bronchoconstriction in response to stimuli.
   • Contributed by inflammation, structural changes, and neuroregulation.
   • Clinical Relevance: Effective anti-inflammatory treatment reduces airway hyperresponsiveness.

2. Airway Inflammation

   • Central to asthma’s pathogenesis.
   • Involves:
     • Cells: Mast cells, eosinophils, T lymphocytes.
     • Mediators: Leukotrienes, cytokines, chemokines.
   • Effects:
     • Bronchospasm, oedema, mucus hypersecretion, and airflow limitation.
   • Clinical Relevance: Inhaled corticosteroids (ICS) target inflammation, improving control and preventing exacerbations.

3. Airway Remodelling

   • Chronic inflammation can cause structural changes:
     • Subepithelial fibrosis, smooth muscle hypertrophy, and mucous gland hyperplasia.
   • May lead to irreversible airflow obstruction.
   • Clinical Relevance: Early and effective treatment can potentially mitigate remodelling.

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Triggers and Risk Factors

1. Allergens

   • Common allergens: Pollen, dust mites, mould, pet dander.
   • Allergen sensitisation is a major risk factor, especially in children.
   • Management: Allergen avoidance and antihistamines when indicated.

2. Exercise

   • Can induce bronchospasm, especially in cold, dry air.
   • Management: Pre-treatment with a short-acting beta-agonist (SABA).

3. Environmental Factors

   • Viral Respiratory Infections: RSV, rhinovirus increase risk.
   • Tobacco Smoke: Increases risk and reduces ICS effectiveness.
   • Air Pollution: Associated with exacerbations and disease development.
   • Occupational Irritants: Chemical fumes, dust, and gases.

4. Other Risk Factors

   • Family history, atopic conditions, obesity.
   • Clinical Relevance: Risk factor assessment helps tailor prevention and management strategies.

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UK Guidelines: BTS/SIGN/NICE

The joint BTS/SIGN/NICE guideline (NG245, 2024) provides comprehensive recommendations for diagnosing, monitoring, and managing asthma.

1. Diagnosis

• Key Elements:
  • Detailed history of symptoms and triggers.
  • Spirometry to confirm airflow obstruction (FEV₁/FVC <70%).
  • Consider additional tests (e.g., FeNO) for diagnostic uncertainty.
• Special Populations:
  • Children under 5 years: Diagnosis primarily clinical.
  • Occupational asthma: Assess exposure history.

2. Monitoring

• Regular monitoring using:
  • Symptom assessments (e.g., Asthma Control Test).
  • Lung function tests (e.g., peak flow monitoring).
  • Risk factor evaluation for exacerbations.
• Personalised strategies for high-risk patients.

3. Management

• Pharmacological Treatment:
  • Adults and Adolescents:
    • Preferred controller: Low-dose ICS-formoterol (as-needed or MART).
    • Stepwise escalation based on severity.
    • Consider leukotriene receptor antagonists (LTRA) or long-acting muscarinic antagonists (LAMA) for uncontrolled asthma.
  • Children:
    • Tailored ICS doses; MART for severe cases.
• Non-Pharmacological Strategies:
  • Smoking cessation, allergen avoidance, and education on self-management.
• Special Considerations:
  • Management during pregnancy and adolescence.
  • Risk-stratified care for high-risk patients.

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Asthma Pathway: Acute and Severe Asthma

The joint asthma pathway consolidates guidelines for managing difficult asthma and acute exacerbations:

• Acute Exacerbations:
  • SABA and systemic corticosteroids as first-line treatments.
  • Oxygen therapy for hypoxia.
  • Escalation to ICU for life-threatening cases.
• Severe Asthma:
  • Referral to specialised centres.
  • Biologic therapies (e.g., anti-IgE, anti-IL-5) for eligible patients.

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Role of Pharmacists

Pharmacists are integral to asthma management, with responsibilities including:

1. Education:
   • Teach inhaler technique and adherence strategies.
   • Educate patients on identifying and avoiding triggers.
2. Monitoring:
   • Assess symptom control and medication side effects.
   • Encourage regular follow-ups for lung function monitoring.
3. Optimisation of Therapy:
   • Identify candidates for step-up or step-down therapy.
   • Collaborate with healthcare teams to adjust treatment plans.

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Conclusion

Asthma is a complex, chronic condition requiring a multifaceted approach to management. By understanding its pathophysiology, recognising triggers, and applying evidence-based guidelines, pharmacists can significantly improve patient outcomes and quality of life.

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References

1. National Asthma Education and Prevention Program. (2002). Expert Panel Report: Guidelines for the Diagnosis and Management of Asthma. In National Heart, Lung, and Blood Institute. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK7223/

2. Busse, W. W., & Lemanske, R. F. (2001). Asthma. New England Journal of Medicine, 344(5), 350-362. Retrieved from https://pubmed.ncbi.nlm.nih.gov/10608420/

3. Mayo Clinic. (n.d.). Asthma: Symptoms and Causes. Retrieved from https://www.mayoclinic.org/diseases-conditions/asthma/symptoms-causes/syc-20369653

4. Asthma + Lung UK. (n.d.). Asthma Triggers. Retrieved from https://www.asthmaandlung.org.uk/conditions/asthma/asthma-triggers

5. British Thoracic Society. (n.d.). Asthma Guidelines. Retrieved from https://www.brit-thoracic.org.uk/quality-improvement/guidelines/asthma/

6. National Institute for Health and Care Excellence (NICE). (2023). Asthma: Diagnosis, Monitoring, and Chronic Asthma Management (Guideline NG245). Retrieved from https://www.nice.org.uk/guidance/ng245