investigations in COPD

Last edited 06/2020 and last reviewed 06/2020

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, if patients 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
    • spirometry 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:
  • 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)