COPD (summary)

COPD (chronic obstructive pulmonary disease) is defined as a condition characterised by persistent air flow limitation that is usually progressive and associated with an enhanced chronic inflammatory response in the airways and the lung to noxious particles or gases ¹.

Reference article

This is a summary article; read more in our article on COPD.

Terminology

The current definition of COPD does not include the terms chronic bronchitis or emphysema:

• chronic bronchitis is defined as the presence productive cough for three months in each of two successive years in a patient in whom other causes of chronic cough (e.g. bronchiectasis) have been excluded; patients with chronic bronchitis are not considered to have COPD unless they have airflow obstruction
• emphysema is a pathological term defined as destruction of the alveoli walls; this is one of the structural abnormalities that can be present in patients with COPD but can also be found in persons with normal lung function ¹

Summary

• epidemiology
  • highest prevalence among the over 60s
  • worldwide prevalence of approximately 10% ²
  • increased prevalence among men (approaching equality)
  • severe genetic form is seen in younger females
• presentation
  • symptoms tend to be progressive
    • exertional dyspnoea is the most common early symptom
    • chronic cough and sputum production
    • less commonly wheezing and chest tightness 
  • may present with
    • chronic daily respiratory symptoms
    • recurrent acute exacerbations
    • relatively little respiratory complaints but an extremely sedentary lifestyle due to the exertional dyspnea
• pathophysiology
  • most common risk factor is cigarette smoking
  • chronic irritants cause an inflammatory response in the respiratory tract which is amplified in COPD-prone patients
  • chronic inflammation leads to structural changes
  • changes occur predominantly in the peripheral airways but also in the large airways, lung parenchyma and pulmonary vasculature
• investigation
  • spirometry
    • post-bronchidialtor FEV1/FVC ratio less than 0.7
    • in the absence of an alternative explanation for the symptoms and airflow limitation is diagnostic of COPD ¹
  • chest x-ray
• role of imaging
  • exclude alternative diagnoses
  • evaluate for co-morbidities
    • e.g. interstitial lung disease, lung cancer with airway obstruction
  • in acute exacerbations, look for complicating processes
    • e.g. pneumonia, cardiac failure, pneumothorax
• radiographic features
  • chest x-ray
    • poor sensitivity to detect COPD
    • possible findings include:
      • flattened diaphragm due to hyperexpansion
      • decreased peripheral bronchovascular markings
      • increased lung lucency (parenchymal loss)
      • bulla (round focal lucency over 1 cm)
      • prominence of the hilar vessels in pulmonary hypertension
  • CT chest
    • may determine the presence, pattern and extent of emphysema
    • emphysema can be categorised as:
      • centrilobular emphysema: this is the most common type of smoking related emphysema; it is called centrilobular because the destruction of parenchyma is centred around the terminal bronchiole, which is in the centre of the secondary pulmonary lobule, and it tends to be more marked in the upper zones
      • panlobular emphysema: this type of emphysema is associated to alpha-1-antitripsin deficiency but can also be seen in smoking related emphsyema, usually mixed with centrilobular emphysema; it is called panlobular because it affects all the areas of the lung lobule more or less equally
      • paraseptal emphysema: this term is used to describe emphysematous lesions in the parenchyma adjacent to the pleural surfaces
    • other findings include
      • bronchial wall thickening
      • air trapping (small airway obstruction)
      • narrowing of the trachea in the coronal plane
      • pulmonary artery enlargement in pulmonary hypertension
• treatment
  • smoking cessation
  • bronchodilators with or without inhaled corticosteroids
  • oxygen therapy may be required in severe cases
  • treatment of the underlying chest infection