Diagnostics

Indication: all patients with typical symptoms of COPD and/or exposure to COPD risk factors

Procedure: Spirometry is performed after inhalation with a short-acting beta-agonist (SABA) or short-acting muscarinic antagonist (SAMA).

Key finding: FEV1/FVC < 70% after bronchodilator inhalation

Typical supportive findings

• ↓ FEV1

• Normal or ↓ FVC

• In the presence of significant emphysema and small airway abnormalities:

  • ↑ TLC (total lung capacity), FRC (functional residual capacity), RV (residual volume), and intrathoracic gas volume

  • ↓ DLCO

Used to assess the reversibility of bronchoconstriction

• Change in FEV1 < 12%: irreversible bronchoconstriction

• Change in FEV1 > 12%: reversible bronchoconstriction

The degree of reversibility alone cannot reliably distinguish between the diagnosis of asthma vs. COPD.

Pulse oximetry

• Indicated in patients with signs of respiratory failure or signs of right heart failure

• Check O2 saturation to assess for indications for long-term oxygen therapy.

ABG

• Indication: O2 saturation < 92% or acute illness (e.g., altered mental status, acute exacerbation)

• Findings: Hypoxemia and hypercapnia are common.

  • Decreased pO2: partial respiratory failure

  • Decreased pO2 and increased pCO2: global respiratory failure

  • Many individuals with severe COPD have chronic hypercapnia due to CO2 trapping from hyperinflation and progressive loss of pulmonary elasticity.

Serum α1-antitrypsin level: Screen all patients with COPD for AATD at diagnosis.

CBC

• ↑ Hematocrit and secondary polycythemia [17]

• Eosinophil counts impact considerations for the use of inhaled corticosteroids.

ECG/TTE: may show signs of right ventricular hypertrophy [21][22]

X-ray chest: not indicated for confirming the diagnosis (low sensitivity, especially during the early stages)

• Indications

  • To assess for alternative diagnoses and/or identify significant comorbidities (e.g., pulmonary fibrosis, bronchiectasis, cardiomegaly)

  • AECOPD

• X-ray findings of COPD

  • Hyperinflated lungs (barrel chest)

  • Hyperlucency of lung tissue (decreased lung markings)

  • Increased anteroposterior diameter

  • Pushed down and flattened diaphragm

  • Horizontal ribs and widened intercostal spaces

  • Long narrow heart shadow

  • Parenchymal bullae or subpleural blebs (pathognomonic of emphysema)

  • Increased retrosternal space on lateral view as a result of emphysematous changes in the lung tissue

CT chest

• Indications

  • Evaluation for complications or differential diagnoses

  • Surgery planning (e.g., lung volume reduction, lung transplantation)

• Findings: similar to x-ray findings

  • Centriacinar emphysema: common in patients with COPD and a history of tobacco use

  • Panacinar emphysema: common in patients with AATD