From the Guidelines
Pulmonary function tests, particularly spirometry, are crucial for diagnosing and managing Chronic Obstructive Pulmonary Disease (COPD), as they provide objective measurements of airflow obstruction and disease severity, guiding treatment decisions and monitoring progression 1. The most important pulmonary function test for COPD is spirometry, which measures FEV1 (forced expiratory volume in one second) and FVC (forced vital capacity).
- A post-bronchodilator FEV1/FVC ratio less than 0.7 confirms airflow obstruction characteristic of COPD, as recommended by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) report 1.
- The severity of COPD is classified based on FEV1 percentage of predicted value, with categories including mild, moderate, severe, and very severe. Additional pulmonary function tests, such as lung volume measurements and diffusion capacity (DLCO), can provide further information on hyperinflation, air trapping, and gas exchange impairment.
- These tests are essential for determining the appropriate treatment, including bronchodilators, inhaled corticosteroids, and oxygen therapy, and for identifying candidates for interventions like lung volume reduction procedures 1. The use of pre- and post-bronchodilator spirometry is recommended for the diagnosis of COPD, with the post-bronchodilator FEV1/FVC ratio being the most important measurement 1. It is also important to consider the potential variability in FEV1/FVC results due to variable expiratory times influencing the FVC values obtained, and the use of forced expiratory volume in 6 s (FEV6) rather than FVC has been suggested as a means of overcoming this variability 1.
- However, the GOLD 2025 report recommends using the FEV1/FVC ratio to identify airflow obstruction, and if there is a strong clinical suspicion of COPD and the FEV1/FVC ratio is normal, further follow-up and investigations, including assessment of the FEV1/SVC ratio, are recommended 1.
From the FDA Drug Label
The 8 trials enrolled patients with nonreversible obstructive lung disease (FEV 1 /FVC ≤70% and ≤12% or 200 mL improvement in FEV 1 in response to 4 puffs of albuterol/salbutamol) COPD exacerbations and lung function (FEV 1) were co-primary efficacy outcome measures in the four 1-year trials.
The role of pulmonary function tests in Chronic Obstructive Pulmonary Disease (COPD) is to measure lung function, specifically FEV1 (Forced Expiratory Volume in 1 second), which is used as a primary efficacy outcome measure to assess the severity of COPD and the effectiveness of treatment 2.
- Pulmonary function tests are used to diagnose and monitor COPD.
- FEV1/FVC ratio is used to confirm nonreversible obstructive lung disease.
From the Research
Role of Pulmonary Function Tests in COPD
Pulmonary function tests play a crucial role in the diagnosis and management of Chronic Obstructive Pulmonary Disease (COPD). The key tests used include:
- Spirometry to assess airway obstruction 3, 4, 5, 6
- Full-body plethysmography to assess lung hyperinflation and pulmonary emphysema 3
- Diffusion capacity to assess gas exchange 3, 6
- Exercise testing to assess exercise tolerance and phenotyping of COPD 6
Diagnosis and Staging of COPD
Pulmonary function testing is essential for the diagnosis and staging of COPD severity. The current diagnostic criterion for airflow obstruction is a ratio of forced expiratory volume in 1 second (FEV1) to forced vital capacity (FVC) < 70% 4, 5. However, this definition can lead to false-negative determinations in younger patients and false-positive determinations in the elderly 5.
Treatment Guidance
Pulmonary function testing is used to guide treatment decisions, including:
- Pharmaceutical treatment for patients with co-existing airway obstruction 3
- Non-pharmaceutical treatment, such as endoscopic or surgical lung volume reduction, long-term oxygen therapy, long-term non-invasive ventilation, and lung transplantation 3
- Rehabilitation programs and guideline adherence 4
Limitations of Pulmonary Function Tests
While pulmonary function tests are essential for the diagnosis and management of COPD, they have limitations. For example: