Diagnostic Criteria for COPD Exacerbations
A COPD exacerbation is defined as an acute worsening of respiratory symptoms that results in additional therapy. 1
Key Diagnostic Features
Cardinal Symptoms
- Increased dyspnea is the key symptom of an exacerbation 1
- Other symptoms include:
Classification of Exacerbations
COPD exacerbations are classified based on treatment requirements:
- Mild: Treated with short-acting bronchodilators only 1
- Moderate: Treated with short-acting bronchodilators plus antibiotics and/or oral corticosteroids 1
- Severe: Patient requires hospitalization or visits the emergency room; may be associated with acute respiratory failure 1
Differential Diagnosis
As comorbidities are common in COPD patients, exacerbations must be differentiated from:
- Acute coronary syndrome 1, 2
- Worsening congestive heart failure 1
- Pulmonary embolism 1
- Pneumonia 1, 2
- Pneumothorax 2
- Lung cancer 2
Causative Factors
Infectious Triggers
- Respiratory viral infections are the main trigger 1, 2
- Bacterial infections are also common causes 1, 2
- Viral infections can predispose airways to bacterial superinfection 2
Environmental Factors
- Environmental factors may initiate or amplify exacerbation events 1
Risk Factors for Exacerbations
Patient Characteristics
- Frequent exacerbator phenotype (defined as two or more exacerbations per year) 1
- Worse lung function and lower exercise capacity 1
- Chronic bronchitis 1
- Increased ratio of pulmonary artery to aorta cross-sectional dimension (ratio > 1) 1
- Greater percentage of emphysema or airway wall thickness on CT imaging 1
Diagnostic Approach
Essential Assessments
- Chest radiography to exclude pneumonia, pneumothorax, pulmonary edema, and lung cancer 2
- Sputum culture and sensitivity when:
- Purulent sputum is present
- Previous antibiotic treatment was ineffective
- In severe exacerbations requiring hospitalization 2
- Arterial blood gases remain the standard approach to assessing gas exchange in patients with COPD exacerbation 3
Laboratory Findings
Proposed laboratory criteria that may help confirm an exacerbation include:
- Oxygen desaturation ≤4% below stable state 4
- Elevated levels of circulating blood neutrophils or eosinophils 4
- Elevated C-reactive protein (≥3 mg·L-1) 4
Clinical Pitfalls and Challenges
- At 8 weeks after an exacerbation, 20% of patients have not recovered to their pre-exacerbation state 1
- COPD exacerbations increase susceptibility to additional events 1
- Patients with frequent exacerbations have worse health status and morbidity than those with less-frequent exacerbations 1
- Lower lung density and thickened bronchial walls on CT scan are associated with increased mortality risk after an acute exacerbation 1
- The cardinal symptoms of COPD exacerbation are nonspecific and can result from acute cardiorespiratory illnesses other than COPD 4