What is the difference between emphysema and Chronic Obstructive Pulmonary Disease (COPD)?

Difference Between Emphysema and COPD

Emphysema is a specific pathological condition characterized by permanent destructive enlargement of airspaces distal to terminal bronchioles without obvious fibrosis, while COPD is a broader disorder characterized by reduced maximum expiratory flow and slow forced emptying of the lungs that encompasses both emphysema and airway disease components. 1

Definitions and Pathophysiology

• COPD is characterized by reduced maximum expiratory flow and slow forced emptying of the lungs that doesn't change markedly over several months, with airflow limitation that is slowly progressive and irreversible 1
• Emphysema is defined anatomically as a permanent destructive enlargement of airspaces distal to the terminal bronchioles without obvious fibrosis 1
• COPD's airflow limitation results from varying combinations of airway disease and emphysema, with the relative contribution of these processes being difficult to define in living patients 1

Types of Emphysema

• Two major patterns of emphysema are recognized with distinct functional consequences 1:
  • Panacinar emphysema: involves destruction of the entire acinus
  • Centriacinar emphysema: respiratory bronchioles, alveolar ducts, and alveoli at the center of the acinus are destroyed, but surrounding alveoli remain intact
• An additional form is paraseptal emphysema, which affects areas adjacent to connective tissue septa 1

Components of COPD

COPD includes several components:

• Emphysema: the parenchymal destruction component 1
• Chronic bronchitis: defined by chronic or recurrent increases in bronchial secretions causing expectoration present on most days for at least 3 months a year, for at least two successive years 1
• Small airway disease: characterized by inflammation, increased wall muscle mass, fibrosis, obliteration and airway narrowing 1

Pathological Differences

• Emphysema specifically involves destruction of lung parenchyma with loss of alveolar attachments to the airway perimeter 1
• COPD's airway component consists of decreased luminal diameters due to increased wall thickening, increased intraluminal mucus, and changes in the lining fluid of small airways 1
• In COPD, changes also occur in pulmonary circulation, the right heart, and respiratory muscles as the disease progresses 1

Functional Consequences

• Emphysema results in loss of lung recoil, which may appear early in the development of panacinar emphysema 1
• In mild to moderate airflow limitation, the decrease in maximum flow could be due to either loss of recoil (emphysema) or small airway abnormalities 1
• Emphysema is considered the most important factor in airflow limitation in severe COPD, while changes in small airways play a greater role in mild to moderate COPD 1

Clinical Implications

• Patients with severe emphysema tend to have lower body mass index and poorer quality of life compared to those with the same degree of airflow limitation but less emphysema 2
• The severity of emphysema varies widely even among patients with the same stage of COPD 2
• Chronic bronchitis symptoms are equally distributed irrespective of emphysema severity 2

Relationship Between Emphysema and COPD

• Emphysema is a COPD-phenotype characterized by destruction of lung parenchyma 3
• Not all COPD patients have emphysema, and the degree of emphysema can vary significantly among patients with the same degree of airflow limitation 2
• Historically, two main COPD phenotypes have been described: chronic bronchitis and emphysema, though these do not fully reflect the heterogeneity of COPD 4

Treatment Considerations

• For COPD with emphysema, smoking cessation is essential 1
• Pharmacological treatments may have less favorable effects in emphysematous than in non-emphysematous COPD patients 3
• Wixela Inhub® 250/50 is indicated for twice-daily maintenance treatment of airflow obstruction in patients with COPD, including chronic bronchitis and/or emphysema 5

Common Pitfalls and Caveats

• Failing to recognize that emphysema is a component of COPD, not a separate disease entity 1
• Assuming all COPD patients have emphysema - the severity of emphysema varies widely even among patients with the same stage of COPD 2
• Overlooking that emphysema can be present without meeting the full criteria for COPD diagnosis 4
• Not appreciating that emphysema predominantly affects lung parenchyma while COPD also involves airway disease 1