Medicine – Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a common, progressive respiratory disorder characterised by persistent airflow limitation that is not fully reversible. The airflow obstruction usually develops gradually over years and reflects a combination of small-airway disease, chronic bronchitis, and emphysema.

COPD is associated with substantial morbidity, recurrent exacerbations, reduced exercise tolerance, impaired quality of life, and increased mortality.

1. Definition

COPD is characterised by chronic respiratory symptoms together with persistent airflow obstruction.

The obstruction does not fluctuate markedly over short periods in the way that asthma often does, although some reversibility can still be present.

Modern diagnosis relies on post-bronchodilator spirometry, rather than simply describing airflow obstruction as “fixed.”

2. Main Cause

The most important risk factor is cigarette smoking.

Long-term exposure to tobacco smoke causes chronic airway inflammation, mucus hypersecretion, small-airway narrowing, and destruction of alveolar tissue.

However, COPD can also occur in never-smokers because of factors such as biomass fuel exposure, occupational dusts and fumes, air pollution, impaired lung development, and α1-antitrypsin deficiency.

3. Chronic Bronchitis and Emphysema

Patients with COPD may have varying proportions of chronic bronchitis, small-airway disease, and emphysema.

These abnormalities frequently overlap, so patients do not usually fall neatly into one category.

4. Chronic Bronchitis

Chronic bronchitis is a clinical definition.

Traditionally, it is defined as a productive cough for at least 3 months in each of 2 consecutive years, after excluding other causes of chronic cough.

The condition reflects chronic mucus hypersecretion and airway inflammation.

5. Emphysema

Emphysema is a pathological condition characterised by permanent enlargement of airspaces distal to the terminal bronchioles with destruction of alveolar walls.

This destruction reduces elastic recoil and causes premature airway collapse during expiration.

Although originally defined pathologically, emphysema can now often be identified and quantified on CT imaging.

Clinical Features

6. Chronic Cough

A chronic cough is common and is often productive of sputum.

Some patients may have cough and sputum production for years before significant breathlessness develops.

7. Breathlessness

Progressive exertional breathlessness is one of the most important symptoms of COPD.

It usually worsens gradually over time and eventually may limit ordinary daily activities.

8. Wheeze

Wheeze may occur because of airflow narrowing and dynamic airway collapse.

Its presence does not automatically indicate asthma, since wheeze is common in COPD as well.

9. Recurrent Exacerbations

Patients may experience recurrent acute exacerbations, characterised by a sustained worsening of respiratory symptoms beyond normal day-to-day variation.

Typical features include increased breathlessness, increased cough, greater sputum volume, and sometimes increased sputum purulence.

Exacerbations may be triggered by viral infections, bacterial infections, air pollution, or other environmental factors.

Spirometry

10. FEV₁/FVC Ratio

The diagnosis of persistent airflow obstruction is based on spirometry.

The modern standard is a post-bronchodilator FEV₁/FVC ratio <0.70.

Older teaching sometimes used thresholds such as <75%, but the fixed 0.70 ratio is more commonly used in modern guidelines, with interpretation adjusted for age when appropriate.

11. FEV₁

FEV₁ is useful for assessing the degree of airflow limitation.

An FEV₁ below 80% predicted may support obstructive lung disease, but COPD diagnosis is not based on FEV₁ alone.

Severity assessment now also considers symptoms, exacerbation frequency, hospitalisations, oxygenation, comorbidities, and functional limitation, not just spirometric percentage bands.

Acute Management

12. Bronchodilators

Acute exacerbations are treated with short-acting bronchodilators, typically a short-acting β₂-agonist such as salbutamol, often with an antimuscarinic such as ipratropium.

Nebulised therapy may be used in more severe attacks.

13. Controlled Oxygen Therapy

Oxygen must be given carefully in patients at risk of hypercapnic respiratory failure.

In many acute COPD exacerbations, the usual target oxygen saturation is 88–92% until arterial blood gas results are available.

The aim is to correct dangerous hypoxaemia without causing excessive worsening of CO₂ retention.

14. Corticosteroids

Short courses of systemic corticosteroids are commonly used in moderate or severe exacerbations because they can shorten recovery time and improve lung function.

They are not used simply as an old-style “steroid reversibility trial” to decide long-term treatment.

15. Antibiotics

Antibiotics may be indicated when there is evidence of bacterial infection, especially with increased sputum purulence, increased sputum volume, or more severe exacerbation requiring ventilation.

Chronic Management

16. Smoking Cessation

Smoking cessation is the single most important intervention for patients who smoke.

It slows the accelerated decline in lung function and reduces exacerbations, cardiovascular risk, and overall mortality.

It is more accurate to say that smoking cessation is the most important modifiable measure rather than the only treatment that can influence disease progression.

17. Vaccination

Patients with COPD should receive appropriate influenza vaccination and pneumococcal vaccination.

Other vaccines may also be indicated depending on age and local recommendations.

18. Short-Acting Bronchodilators

Patients with intermittent symptoms may use a short-acting β₂-agonist (SABA) or a short-acting muscarinic antagonist (SAMA) as required.

These drugs provide rapid symptom relief.

19. Long-Acting Bronchodilators

For persistent symptoms, modern treatment generally relies on long-acting bronchodilators.

These include:

LABA – long-acting β₂-agonists

and

LAMA – long-acting muscarinic antagonists.

Many symptomatic patients benefit from LABA + LAMA combination therapy.

This has largely replaced older stepwise regimens based mainly on repeated short-acting bronchodilator use.

20. Inhaled Corticosteroids

Inhaled corticosteroids (ICS) are not routinely given to every patient with COPD.

They are most useful in selected patients with frequent exacerbations, higher blood eosinophil counts, or coexisting asthma features.

ICS is often used in combination with long-acting bronchodilators rather than as monotherapy.

The older practice of giving a steroid trial and continuing ICS only if FEV₁ improves by >15% is no longer the standard approach.

21. Triple Therapy

Patients with persistent exacerbations despite dual bronchodilation may benefit from triple inhaler therapy:

LABA + LAMA + ICS.

The decision depends on symptoms, exacerbation history, blood eosinophils, pneumonia risk, and other clinical factors.

22. Pulmonary Rehabilitation

Pulmonary rehabilitation is an important non-drug treatment for symptomatic patients.

It combines exercise training, education, breathing strategies, and multidisciplinary support and can improve exercise capacity, breathlessness, and quality of life.

23. Long-Term Oxygen Therapy

Long-term oxygen therapy (LTOT) is indicated in selected patients with persistent severe chronic hypoxaemia.

It is not prescribed simply because the COPD is spirometrically “severe.”

Typical eligibility depends on arterial oxygen tension and complications such as pulmonary hypertension, cor pulmonale, or secondary polycythaemia.

Complications

24. Respiratory Failure

Advanced COPD can cause respiratory failure.

Patients may initially develop hypoxaemia and later progress to type 2 respiratory failure with hypercapnia, especially during exacerbations.

25. Recurrent Exacerbations

Frequent exacerbations accelerate functional decline and are associated with worse quality of life and increased mortality.

Patients with repeated exacerbations may require escalation of inhaled therapy and further investigation for contributing factors.

26. Cor Pulmonale

Chronic hypoxaemia can cause hypoxic pulmonary vasoconstriction, leading to pulmonary hypertension.

Over time, this may produce right-sided heart strain and cor pulmonale.

27. Secondary Polycythaemia

Persistent hypoxaemia stimulates erythropoietin production and may cause secondary polycythaemia.

The resulting increase in red cell mass can increase blood viscosity.

28. Pneumothorax

Patients with emphysema may develop bullae, which can rupture and produce a spontaneous pneumothorax.

This may cause sudden pleuritic chest pain and acute worsening of breathlessness.

29. Lung Cancer

COPD is strongly associated with lung cancer, largely because tobacco exposure is a major shared risk factor.

COPD itself may also be associated with additional cancer risk beyond smoking alone.

30. Osteoporosis

Patients with COPD have an increased risk of osteoporosis.

Contributing factors include smoking, low body weight, reduced physical activity, chronic inflammation, vitamin D deficiency, and repeated or prolonged exposure to systemic corticosteroids.

31. Pink Puffer and Blue Bloater

Older teaching divided COPD patients into “pink puffers” and “blue bloaters.”

The pink-puffer pattern was associated mainly with emphysema, marked breathlessness, relatively preserved ventilation, and normal or low PaCO₂ until later disease.

The blue-bloater pattern was associated more with chronic bronchitis, hypoxaemia, hypercapnia, cyanosis, pulmonary hypertension, and cor pulmonale.

These terms are now regarded as historical rather than formal clinical classifications, because most patients have overlapping features.

Key Clinical Pattern

Think of COPD in a patient, usually with a significant smoking or inhalational exposure history, who has progressive exertional breathlessness, chronic cough with or without sputum, wheeze, and recurrent exacerbations.

The key spirometric finding is persistent post-bronchodilator airflow obstruction with FEV₁/FVC <0.70.

Modern long-term treatment centres on smoking cessation, vaccination, long-acting bronchodilators, pulmonary rehabilitation, selective use of inhaled corticosteroids, prevention of exacerbations, and LTOT when severe chronic hypoxaemia is present.

Important complications include respiratory failure, recurrent exacerbations, pulmonary hypertension and cor pulmonale, secondary polycythaemia, pneumothorax, osteoporosis, and lung cancer.