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🌟 Chronic obstructive pulmonary disease (COPD)

 🎯 Pathology​

  • a chronic and progressive lung condition that is characterised by inflammation in the airway leading to airflow limitation

  • COPD is a broad term that encompasses 2 important conditions: chronic bronchitis and emphysema

 ⚡️ Chronic bronchitis​

  • productive cough for > 3 months per year for 2 consecutive years

  • known as “blue bloater” because of cyanosis

  • patients are cyanosed but not breathless

⚡️ Emphysema​

  • destruction of the alveolar walls which impairs elastic recoil of the lungs as well as reduces the surface area available for gas exchange

  • known as “pink puffer” because patients tend to have a barrel-shaped chest and breathe out by pursing their lips as it’s hard to expel air from the lungs

  • patients are breathless but not cyanosed

 ⚡️ COPD versus asthma​

  • COPD is almost always caused by smoking

  • COPD tends to affect the elderly (if the patient is < 60 years or a non-smoker, the aetiology may be due to alpha-1 antitrypsin deficiency)

  • COPD is irreversible (unlike asthma)

💡 Causes​

  • smoking: causes centriacinar emphysema

  • alpha-1 antitrypsin deficiency: causes panacinar emphysema

🩺 Clinical features​

  • symptoms

    • dyspnoea

  • signs

    • productive cough

    • wheeze

    • quiet breath sounds over bullae

    • no clubbing

    • reduced cricosternal distance

    • barrel-shaped chest

    • signs of cor pulmonale

    • jugular venous distension

    • right parasternal heave

    • peripheral oedema

 🕵️‍♂️ Investigations​

  • full blood count

    • shows secondary polycythaemia

    • raised WBCC if infection

  • best test

    • post-bronchodilator spirometry: obstructive pattern as FEV1/FVC < 70%

    • there is little to no response to reversibility testing with beta-2 agonists (unlike asthma)

  • chest x-ray

    • hyperinflation, bullae, flat hemidiaphragms, thin-appearing heart

  • ABG

    • hypoxia with or without hypercapnia

  • ECG

    • right atrial and ventricular hypertrophy

  • sputum culture

    • considered if COPD exacerbation due to bacterial infection

💡 Assessing the severity of COPD​

  • the severity is categorised using the post-bronchodilator FEV1

Post-bronchodilator FEV1/FVC ratio
Airflow limitation severity
Post-bronchodilator FEV1 measurement
< 0.7
< 0.7
< 0.7
Mild
Moderate
50-79% predicted
Severe
30-49% predicted
≥ 80% predicted
< 0.7
Very severe
< 30% predicted

💆‍♂️ Management​

  • conservative

    • smoking cessation

    • vaccinations: annual influenza vaccine, one-off pneumococcal vaccination

    • pulmonary rehabilitation

  • medical

    • 1st line: short-acting beta-2 agonist (SABA) e.g. salbutamol, or short-acting muscarinic antagonist (SAMA) e.g. ipratropium

    • 2nd line: determine if the patient has asthma or steroid-responsive features

      • positive —> add long-acting beta-2 agonist (LABA) + inhaled corticosteroids (ICS)

      • negative —> add long-acting beta-2 agonist (LABA) + long-acting muscarinic antagonist (LAMA)

    • 3rd line: LABA + LAMA + ICS

  • cor pulmonale

    • long-term oxygen therapy

    • loop diuretics for oedema

​​

Features suggestive of asthma or steroid responsiveness:

  • diagnosis of asthma or atopy

  • diurnal variation in FEV1 (≥ 400 ml)

  • diurnal variation in peak expiratory flow (≥ 20%)

  • raised blood eosinophil count

​

Other treatment options

  • oral theophylline

  • prophylactic antibiotic therapy (e.g. azithromycin)

  • mucolytics

  • long-term oxygen therapy

  • lung volume reduction surgery

​

Long-term oxygen therapy (LTOT)

  • if the patient is a CO2 retainer the target oxygen saturation should be maintained between 88-92%

  • patients will need to breathe in oxygen for at least 15 hours a day

  • patients who exhibit any of the following should be assessed for LTOT

    • ​raised JVP

    • peripheral oedema

    • polycythaemia

    • cyanosis

    • FEV1 < 30% predicted

    • SpO2 ≤ 92% on room air

  • frequency of assessment:

    • measure arterial blood gases on 2 occasions 3 weeks apart

  • patients should be offered LTOT if their

    • PaO2 < 7.3 kPa or if PaO2 7.3-8.0 kPa with one of the following:

      • peripheral oedema

      • pulmonary hypertension

      • secondary polycythaemia

      • contraindications

      • smoking

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😢 Acute COPD exacerbation

  • most common cause

    • ​Haemophilus influenzae infection

  • clinical features

    • increased dyspnoea, cough and sputum production

  • management

    • oxygen: titrate oxygen saturation between 88-92%

    • bronchodilators: salbutamol, ipratropium

    • systemic corticosteroids: prednisolone or hydrocortisone

    • chest physiotherapy to help clear sputum

    • non-invasive ventilation (NIV): bilevel positive airway pressure (BiPAP) if increased risk of developing type 2 respiratory failure

    • tracheal intubation if NIV fails

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