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Chronic obstructive pulmonary disease

Background knowledge πŸ§ 

Definition

  • A group of lung diseases characterised by chronic airflow obstruction, which is not fully reversible
  • Includes chronic bronchitis and emphysema

Aetiology

  • Smoking: primary risk factor
  • Biomass fumes (used in heating/cooking)
  • Occupational dusts and chemicals
  • Air pollution
  • Genetic causes: Ξ±1-antitrypsin deficiency
  • Frequent lower respiratory infections during childhood

Pathophysiology

  • Toxic particles β†’ goblet cell hypertrophy β†’ inflammatory infiltrate β†’ remodelling β†’ alveolar destruction

Clinical Features πŸŒ‘️

Symptoms

  • Chronic productive cough
  • Dyspnoea on exertion, progressing to rest dyspnoea
  • Wheeze and chest tightness

Signs

  • Accessory muscle use
  • Tar-stained fingers
  • Tachypnoea
  • Lip pursing
  • Reduced cricosternal distance (<3 fingers)
  • Tracheal tug
  • Indrawing of lower intercostal muscles on inspiration
  • Hyper-resonance (with obliterated cardiac and hepatic dullness)
  • Quiet breath sounds/wheeze/prolonged expiratory phase

Investigations πŸ§ͺ

Investigations

  • Spirometry
  • Chest X-ray: hyperinflated lungs, flat diaphragms, bullae
  • Arterial blood gas: chronic respiratory acidosis and hypoxaemia in advanced stages.
  • Ξ±1-antitrypsin levels if suspect genetic cause

Spirometry findings in COPD

  • Obstructive pattern: ↓FEV1 (<80%), normal FVC (>80%), ↓FEV1/FVC ratio (<0.7)
  • Limited reversibility (unlike asthma)
  • FEV1 is also used to grade severity of COPD
    • Mild (β‰₯80%)
    • Moderate (50-80%)
    • Severe (30-50%)
    • Very severe (<30%)

Learn more…

Spirometry is covered in full here!

Management πŸ₯Ό

Chronic management

Inhaled therapy

Abbreviations: SABA = short-acting Ξ²2 agonist; SAMA = short-acting muscarinic antagonist; LABA = long-acting Ξ²2 agonist; LAMA = long-acting muscarinic antagonist; ICS = inhaled corticosteroid

Other interventions

  • Stop smoking: prevents progression
  • Pulmonary rehabilitation: exercise and education programme.
  • Oxygen therapy: for chronic hypoxaemia
  • Vaccination: annual influenza and pneumococcal vaccines
  • Lung transplant

Indications for oxygen therapy in chronic COPD

  • Long-term oxygen therapy: considered in chronic hypoxaemia if PaO2<7.3kPa (or <8kPa in presence of pulmonary hypertension or secondary polycythaemia)
  • Ambulatory home oxygen therapy: considered if hypoxaemic on exertion/activity

Management of an acute exacerbation

  • Controlled oxygen aiming 88-92% saturations or pO2 >8 – see prescribing notes on oxygen therapy)
  • Salbutamol and Ipratropium nebulisers
  • Prednisolone 30mg OD for 7 days
  • Antibiotics if any signs of infection as per local guidelines, e.g. doxycycline
  • Chest physiotherapy
  • Consider BiPAP in hypercapnic respiratory acidosis not responding to medical management (or if you achieve oxygen sats of 88-92%/PaO2 β‰₯8 without a hypercapnic respiratory acidosis despite medical management)

Complications

  • Acute exacerbations
  • Respiratory failure
  • Cor pulmonale
  • Secondary polycythaemia
  • Increased risk of lung cancer
  • Pneumothorax

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