Asthma

• Asthma is a chronic lung condition in which there is chronic inflammation of the airways, and hypersensitivity of the airways
• Features of extrinsic asthma:

  • Identifiable cause
  • Family history of atopy
  • Positive skin prick test
  • Often accompanied by eczema
  • Type 1 hypersensitivity reaction
  • Childhood onset
• Features of intrinsic asthma:

  • No identifiable cause
  • Middle age onset
  • Often associated with chronic bronchitis or cold or exercise induced
• Clinical features of asthma:

  • Wheezing attacks
  • Shortness of breath
  • Symptoms worse at night
  • Frequent cough
• Histological findings in an asthmatic lung:

  • Increased mucus production
  • Goblet cell hyperplasia
  • Higher counts of eosinophils, mast cells and T-helper cells
  • Thickened basement membrane
  • Smooth muscle hypertrophy
  • Narrower lumen
• What happens in the early phase of extrinsic asthma?

  An inhaled allergen crosslinks 2 IgEs on mast cells which degranulate, releasing histamines and prostaglandins. Histamines cause smooth muscle contraction, increased bronchial secretion and increased vascular permeability.
• What happens in the late phase of extrinsic asthma?

  Inflammatory mediators from mast cells cause chemotaxis of eosinophils into the mucosal lining, causing sustained inflammaion
• Triggers of smooth muscle contraction in asthma

  • Muscarinic agonists
  • Histamine
  • Cold air
  • Arachidonic acid metabolites
• Investigations for asthma:

  • Peak expiratory flow test
  • Spirometry
  • Exercise induced bronchoconstriction
  • Skin prick test
• What would you see on inspection of a patient with asthma?

  • Barrel chest
  • Chest wall deformities
• What would you hear on auscultation of a patient with asthma?

  Polyphonic wheezing
• What would you hear on percussion of an asthma patient?

  Hyper resonance
• What primary preventative measures can be used for asthma?

  • Smoking cessation
  • Fresh air
  • Breast feeding
  • Reduced exposure to allergens
  • Weight loss
• Which class of drugs should asthma patients absolutely avoid?

  Beta Blockers
• What pharmacological options are there for asthma patients?

  • Bronchodilators (Beta-2 agonists and anticholinergics)
  • Corticosteroids
  • Leukotriene receptor antagonists
• Features of moderate asthma attack:

  • Saturation >92% in air

  • Pulse <110

  • Respiratory rate <25

  • Speech normal

  • Heavier wheezing

  • PEFR > 75-50% predicted
• Features of severe asthma attack:

  • Pulse >110
  • Respiratory rate >25
  • Difficulty speaking
  • PEFR 33-50%
• What is Status Asthmaticus?

  Acute severe asthma where airway obstruction is unresponsive to drug therapy. It is a medical emergency
• Characteristics of asthma:

  • Airway wall inflammation
  • Reversible airflow obstruction
  • Increase in airway responsiveness
  • Airway wall remodelling
• Features of mild asthma attack:

  • Saturation >92% in air
  • Pulse <110
  • Respiratory rate <25
  • Normal speech
  • Minimal wheeze
  • PEFR >75% predicted
• Asthma management in adults:

  • Step 1 (New) - SABA
  • Step 2 (New + >3 symptoms per week) - Add low dose ICS
  • Step 3 - Add LTRA
  • Step 4 - Add on LABA. LTRA can be kept on or removed.
  • Step 5 - Switch to SABA + MART (includes low dose ICS)
  • Step 6 - Change MART to medium dose ICS
  • Step 7 - Either change MART to high dose ICS, trial additional drug (e.g. theophylline or LAMA) or seek help from specialist.
• Maintenance And Reliever Therapy (MART):

  • combined inhaler containing both ICS and a fast acting LABA