• Clinical science

Chronic obstructive pulmonary disease


Chronic obstructive pulmonary disease (COPD) is a preventable lung disease characterized by airway obstruction due to inflammation of the small airways. It is caused predominantly by inhaled toxins, especially smoking (in 90% of cases), but air pollution and recurrent respiratory infections may also play a role. Some patients are genetically predisposed to COPD, particularly those with α1-antitrypsin deficiency. COPD begins with chronic airway inflammation that usually progresses to emphysema, characterized by irreversible bronchial narrowing and alveolar hyperinflation, which can culminate in the loss of diffusion area. Oxygen absorption and carbon dioxide release become inadequate, leading to hypoxia and hypercapnia. Most patients will present with a combination of dyspnea and chronic cough with expectoration. In later stages, COPD may present with more severe symptoms such as tachypnea, tachycardia, and cyanosis. Diagnosis is primarily based on clinical presentation and lung function tests, which typically show a decreased ratio of forced expiratory volume (FEV) to forced vital capacity (FVC). Imaging studies such as chest x-ray are helpful in assessing disease severity and the extent of possible complications, but they are not required to confirm the diagnosis. Arterial blood gas and pulse oximetry are useful for quickly assessing the patient's O2 status. All COPD patients should be staged according to the staging system of the Global Initiative for Chronic Obstructive Lung Disease (GOLD), which considers a variety of factors (e.g., exacerbations, symptom severity, FEV1). Treatment depends on the GOLD stage but is mainly comprised of short and long-acting bronchodilators (beta agonists and parasympatholytics) and glucocorticoids. In advanced disease, patients often require oxygen supplementation, which is the only treatment that decreases mortality. COPD may cause complications such as pulmonary hypertension or respiratory failure, but the most significant complication is acute exacerbation of COPD (AECOPD).




  • Sex: >
  • The fourth most common cause of death worldwide
  • Prevalence in the USA: 6.3%


Epidemiological data refers to the US, unless otherwise specified.





Airflow limitation in patients with FEV1/FVC < 70%



FEV1 % of the predicted value
GOLD 1 mild ≥ 80%
GOLD 2 moderate 50–79%
GOLD 3 severe 30–49%
GOLD 4 very severe < 30%

Global Initiative for Chronic Obstructive Lung Disease (GOLD)

Patient group Risk Degree of severity Exacerbations/year Symptoms
A Low risk and less symptomatic GOLD 1/2 ≤ 1 Mild symptoms
B Low risk and more symptomatic Severe symptoms
C High risk and less symptomatic GOLD 3/4 ≥ 2 Mild symptoms
D High risk and more symptomatic Severe symptoms





Clinical features

  • Main symptoms
    • Chronic cough with expectoration (expectoration typically occurs in the morning)
    • Dyspnea: initially only on exertion, later continuously
  • Other symptoms

Nail clubbing is not a typical finding in patients with COPD and its presence usually suggests comorbidities such as bronchiectasis, pulmonary fibrosis, or lung cancer!



Physical examination

  • Percussion
    • Hyperresonant lungs
    • Reduced diaphragmatic excursion
  • Auscultation
    • Early inspiratory coarse crackles and wheezing
    • Prolonged expiratory phase; and decreased breath sounds: “silent lung” (silent chest) in advanced COPD
    • Heart sounds may be soft and distant.

Pulmonary function tests

Blood gas analysis (BGA) and pulse oximetry

  • Pulse oximetry: to assess O2 saturation
  • BGA: only indicated when O2 is < 92% or if the patient is severely ill
    • ↓ pO2: partial respiratory failure
    • ↓ pO2 and pCO2: global respiratory failure


  • Not required for routine diagnosis!
  • Chest x-ray: not sensitive, especially during early stages
  • CT chest: used to evaluate possible complications or prior to surgery


  • Laboratory studies:
    • α1-antitrypsin levels should be determined in all patients < 50 years of age.
    • ↑ Serum Hct
  • Sputum examination in cases of suspected pulmonary infection
  • Bronchoscopy: to identify the pathogen in severe and acute exacerbation of COPD of infective etiology, especially if antibiotic treatment fails


Differential diagnoses

Asthma COPD
Initial diagnosis

Common in children and teenagers

Common in the 2nd half of life
Etiology Allergic and non-allergic (analgesic-induced, infectious, chemical, or toxic) Primarily affects smokers
Clinical features Episodic: interspersed with symptom-free phases; sudden onset Chronic and progressive; gradual-onset
Obstruction Reversible Irreversible

Effect of medicines

Responds well to long-term inhaled glucocorticoids Responds well to parasympatholytics (e.g., ipratropium bromide)
Diffusion capacity Normal Reduced


The differential diagnoses listed here are not exhaustive.


General considerations

Medical therapy according to GOLD

Severity First-line treatment Alternative treatment Medication as needed
  • No long-term treatment, but is treated when symptomatic
  • Monotherapy as in severity B
  • Short-acting β2-agonist and/or
  • Short-acting parasympatholytics
  • Combination therapy: long-acting parasympatholytics and long-acting β2-agonists
  • Triple therapy (possibly with PDE-4 inhibitor)
  • Combination therapy with bronchodilators
  • Long-acting parasympatholytics + PDE-4 inhibitor

Other treatment options



Acute exacerbation of chronic obstructive pulmonary disease (AECOPD)

Since acute exacerbation of COPD is a life-threatening emergency, the patient's condition should be assessed as soon as possible and, if necessary, the patient should be admitted to the intensive care unit.

Other complications


We list the most important complications. The selection is not exhaustive.


  • 5-year survival rate: 40–70%, depending on severity of disease
  • 2-year survival rate: 50% in severe COPD
  • Long-term supplemental O2 therapy:Beneficial especially in COPD patients with resting hypoxemia
  • Cessation of tobacco use improves survival in general.