Investigations in COPD

The investigations for COPD include:

• spirometry
  • is the most reproducible and objective measurement of airflow limitation
  • should be performed at the time of diagnosis and to reconsider the diagnosis, for patients who show an exceptionally good response to treatment
  • a decrease in both FEV1 and FVC is seen in COPD
  • measurements are evaluated by comparison with reference values based on age, height, sex and race
  • measure post-bronchodilator spirometry to confirm the diagnosis of COPD
  • should be used to monitor disease progression (1)
• a chest radiograph to exclude other pathologies
• the full blood count - to identify anaemia or polycythaemia
• body mass index (BMI) calculated

Additional investigations which may be useful according to the clinical findings include:

• serial domiciliary peak flow measurements – to exclude asthma if diagnostic doubt remains
• alpha-1 antitrypsin - indicated if early onset, minimal smoking history or family history
• transfer factor for carbon monoxide (TLCO) - to investigate symptoms that seem disproportionate to the spirometric impairment
• pulse oximetry - to assess need for oxygen therapy if cyanosis, or cor pulmonale present, or if FEV1 <50% predicted
• CT scan of the thorax
  • to investigate symptoms that seem disproportionate to the spirometric impairment
  • to investigate abnormalities seen on a chest radiograph
  • to assess suitability for surgery
  • be aware that the presence of emphysema on a CT scan is an independent risk factor for lung cancer (1)
• the ECG may show cor pulmonale:
  • tall P waves
  • right bundle branch block
  • right ventricular hypertrophy
  • for more information regarding the ECG changes in COPD then click here
• echocardiogram - to assess cardiac status if features of cor pulmonale
• arterial blood gases:
  • pink puffer - near-normal gases
  • blue bloater - hypercapnia, hypoxaemia, severe nocturnal hypoxaemia, elevated bicarbonate
• sputum culture – to identify organisms if sputum is persistently present and purulent (1,2)

Reference:

1. NICE. Chronic obstructive pulmonary disease in over 16s: diagnosis and management. NICE guideline NG115. Published December 2018, last updated July 2019
2. Global Initiative for Chronic Obstructive Lung Disease (GOLD). Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease: 2025 report. 2025 [internet publication].