Asthma Lecture Notes

Definition

• Chronic inflammatory disease of the respiratory system.
• Characterized by:
  • Bronchial hyperresponsiveness.
  • Episodic acute asthma exacerbations.
  • Reversible airflow obstruction.

Symptoms

• Common symptoms include:
  • Shortness of breath.
  • Cough.
  • Wheezing.

Presentation

• Often presents in childhood.
• Frequently associated with:
  • Eczema.
  • Hay fever.

Etiology

• Complex and multifactorial:
  • Influenced by genetics and environmental exposure.
  • Triggered by irritants or allergens (e.g., cold air, pollen).

Pathological Processes

1. Airway Inflammation:

   • Trigger leads to bronchial hypersensitivity.
   • Inflammation results in increased mucus production.
   • Causes airflow obstruction.

2. Causes of Airflow Obstruction:

   • Inflammatory Cell Infiltration
   • Mucus Hypersecretion
     • Can lead to mucus plug formation.
   • Smooth Muscle Contraction

3. Reversibility Changes:

   • These may become irreversible:
     • Basement membrane thickening.
     • Collagen deposition and fibrosis.
     • Airway remodeling in chronic asthma:
       • Smooth muscle hypertrophy and hyperplasia.
       • Infiltration of eosinophils (EILs).

Types of Asthma

• Chronic asthma with airway remodeling:
  • Long-term changes due to untreated symptoms.
• Simple asthma:
  • Symptoms include wheezing, shortness of breath, cough (worse at night).

Triggers of Asthma Exacerbations

• Divided into:
  • Avoidable Triggers:
    • Cigarette smoking, allergens (animal dander, molds, pollen).
    • Environmental irritants (cold, dry air, perfumes, renovation materials).
    • Medications (e.g., aspirin, NSAIDs, beta-blockers).
    • Dietary triggers (food chemicals/additives).
  • Unavoidable Triggers:
    • Respiratory tract infections.
    • Exercise.

Diagnosis

• Diagnosis differs by age:
  • In children:
    • Based on history and examination.
    • Improvement with bronchodilators.
  • In older children:
    • Pulmonary tests showing reversibility post-bronchodilator.

Treatment Approach

1. Assess Severity:

2. Stepwise Management:

   • Relievers:
     • Salbutamol (short-acting beta-agonist).
     • Antimuscarinic inhalers.
   • Preventers:
     • Corticosteroid inhalers.
   • Combination treatments:
     • If poorly controlled, add other agents (e.g., monoclonal antibodies).

3. Non-Pharmacological Management:

   • Inhaler techniques.
   • Importance of adherence to treatment.
   • Development of an action plan for exacerbations.

Acute Asthma Episodes

• Classification:
  • Mild to Moderate:
    • Able to speak in full sentences; O2 saturation > 94%.
  • Severe:
    • Use of accessory muscles; unable to complete sentences; O2 saturation between 90-94%.
  • Life-Threatening:
    • Reduced consciousness; exhaustion; hypoxic < 90%; possibility of absent breath sounds.

Treatment of Acute Asthma

• Mild to Moderate:
  • Start with bronchodilators (beta-agonists, antimuscarinics).
• Severe:
  • Add corticosteroids (oral/intravenous).
• Life-Threatening:
  • Addition of magnesium sulfate, aminophylline, adrenaline.
  • Non-invasive ventilation or intubation may be necessary.

Summary

• Asthma is a chronic inflammatory lung disease.
• Characterized by shortness of breath, cough, and wheezing.
• Reversible airflow obstruction treatable with bronchodilators (first-line treatment).