Makindo Medical Notes

Definition

• Asthma is a chronic respiratory illness with acute exacerbations.
• Characterized by expiratory wheeze and reversible airway obstruction.
• Reversibility is key and can be established through history, examination, PEFR records, and spirometry.
• Asthma prevalence is increasing worldwide, with 1000-2000 deaths annually in the UK due to asthma.

Aetiology

• More common in those with hay fever, urticaria, and eczema, with elevated IgE and eosinophils—often termed allergic asthma.
• The rise in allergic conditions may explain the increased incidence of asthma.
• An excess of Th2 over Th1 lymphocytes in nasal and bronchial mucosa is observed, with Th2 lymphocytes inducing IgE production through cytokine release.

Pathology

• A chronic inflammatory condition of the airways.
• Thickening of the lamina reticularis and eosinophilia in bronchial biopsies.
• Curschmann's spirals and Charcot-Leyden granules are suggestive of steroid responsiveness.

Precipitating Factors

• Environmental triggers: cigarette smoke, cold air, irritant gases, perfumes, and deodorants.
• Allergens: house dust mite, Aspergillus spores, viral infections, exercise, and stress.
• Medications: NSAIDs, aspirin (associated with nasal polyps), beta-blockers, and certain food additives like tartrazine.
• Occupational asthma should also be considered in relevant cases.

Clinical Classification

• Intrinsic Asthma: Non-atopic, typically seen in older patients with no evidence of elevated IgE levels.
• Extrinsic Asthma: Atopic, common in children and young adults, associated with elevated IgE levels.

Clinical Features

• Expiratory dyspnoea and wheeze.
• Chest tightness and a cough, which is often nocturnal.
• Reduced chest expansion during episodes.

Diagnosis: Clinical History Compatible with Asthma and...

• An increase in FEV1 by at least 12% (200 mL) after Salbutamol or a trial of steroids.
• A 15% improvement in FEV1 is considered stronger evidence.
• PEFR diary showing more than 20% diurnal variation over 3 days in a week for 2 weeks.
• A decrease in FEV1 of 15% after 6 minutes of exercise supports the diagnosis.

Investigations

• Blood Tests: FBC, U&E, CRP/ESR (usually normal unless there is an infection).
• Atopy Indicators: Elevated eosinophils, IgE levels, and fractional exhaled nitric oxide (FeNO).
• CXR: Typically normal, but may show lobar collapse, mucus plugging, or infiltrates if aspergillus is involved.
• Spirometry: FEV1/FVC ratio < 70% (or below the lower limit of normal) suggests obstructive airway disease.
• PEFR: Shows variability > 20% with time and treatment. A predicted PEFR diary can demonstrate this.
• Bronchodilator Reversibility (BDR) Test: Increase in FEV1 > 12% or 200 mL indicates a positive test.
• Skin Prick Testing: To identify allergens, particularly in cases with eosinophilia or CXR shadowing.

Management

• Short-Acting Beta Agonists (SABA):
  • Salbutamol (Ventolin) or Terbutaline for relief of acute symptoms.
  • Salbutamol nebulisers in cases of acute severe asthma.
• Long-Acting Beta Agonists (LABA): Salmeterol, Formoterol used in combination with inhaled corticosteroids (ICS).
• Inhaled Corticosteroids (ICS):
  • Low dose: Budesonide 200-400 mcg/day or equivalent.
  • Moderate dose: Budesonide 400-800 mcg/day.
  • High dose: Budesonide 800-2000 mcg/day.
• Oral or IV Corticosteroids:
  • Prednisolone 30 mg for severe exacerbations.
  • Hydrocortisone IV for acute severe asthma.
• Steroid-Sparing Agents: Methotrexate, Ciclosporin, and biologicals like Omalizumab.
• Mast Cell Stabilizers: Sodium cromoglycate for patients responsive to it.
• Biologics: Omalizumab (anti-IgE) for severe allergic asthma.
• Antibiotics: Only if evidence of a bacterial infection.

Drugs Used to Treat Asthma

Standard Escalation Process