What are the results of post-bronchodilator pulmonary function tests (PFTs)?

From the Guidelines

Post-bronchodilator pulmonary function testing (PFT) should be performed using a short-acting bronchodilator, such as albuterol 400 mcg via metered-dose inhaler with spacer or 2.5 mg via nebulizer, with spirometry repeated after 15-20 minutes to assess for bronchodilator reversibility, as recommended by the GOLD Science Committee in 2025 1. The test is essential for diagnosing and differentiating between obstructive lung diseases like asthma and COPD. During the procedure, baseline spirometry measurements are taken first, followed by administration of the bronchodilator, and then spirometry is repeated after 15-20 minutes. A significant improvement in FEV1 (forced expiratory volume in 1 second) of 12% or more and at least 200 mL indicates bronchodilator reversibility, which is characteristic of asthma, as shown in studies such as 1. In COPD, there may be little or no improvement after bronchodilator use. This test helps clinicians determine appropriate treatment strategies, as patients with reversible airflow obstruction often respond well to bronchodilators and inhaled corticosteroids. The procedure is safe for most patients but should be performed by trained personnel who can properly instruct patients on breathing maneuvers and monitor for any adverse reactions to the bronchodilator medication. Some key points to consider when interpreting post-bronchodilator PFT results include:

• The use of pre- and post-bronchodilator spirometry to diagnose COPD, as recommended by the GOLD Science Committee in 2025 1
• The importance of considering the change in FEV1 and FVC when assessing bronchodilator response, as discussed in 1 and 1
• The need to use a standardized protocol for administering the bronchodilator and performing spirometry, as suggested in 1
• The potential for discordant results between pre- and post-bronchodilator spirometry, and the need to consider these results in the context of clinical symptoms and other diagnostic findings, as discussed in 1 and 1.

From the FDA Drug Label

The trials enrolled patients 40 years of age or older with a clinical diagnosis of COPD, a smoking history of more than 10 pack-years, and moderate to very severe pulmonary impairment (post-bronchodilator FEV1 less than 80% predicted normal [GOLD Stage 2-4]; post-bronchodilator FEV1 to FVC ratio of less than 70%). The post-bronchodilatory pulmonary function test (PFT) values are:

• FEV1: less than 80% predicted normal
• FEV1 to FVC ratio: less than 70% 2

From the Research

Post-Bronchodilatory Pulmonary Function Test (PFT) Results

• The studies 3, 4, 5, 6, 7 compared the effects of different bronchodilator combinations on lung function in patients with chronic obstructive pulmonary disease (COPD).
• The combination of salmeterol and tiotropium, with or without fluticasone, was found to be more effective in improving lung function than either bronchodilator alone 3, 4, 5.
• Specifically, the combination of salmeterol, fluticasone, and tiotropium was found to be superior to the other two combinations in terms of preinhalation and postinhalation forced expiratory volume in 1 second (FEV1) 3.
• The study by 4 found that the combination of fluticasone propionate/salmeterol and tiotropium improved trough FEV1 and peak flow rate compared to either treatment alone.
• The study by 5 found that the combination of salmeterol/fluticasone propionate and tiotropium bromide improved post-dose specific airways conductance and trough FEV1 compared to individual treatments.
• The study by 6 found that the combination of tiotropium plus formoterol was superior to salmeterol plus fluticasone in terms of FEV1 area under the curve and peak FEV1.
• The study by 7 found that the combination of tiotropium plus fluticasone propionate/salmeterol improved pre-bronchodilator FEV1 and health-related quality of life compared to tiotropium monotherapy.

Comparison of Different Bronchodilator Combinations

• The studies compared the effects of different bronchodilator combinations, including:

• Salmeterol and tiotropium 3
• Fluticasone propionate/salmeterol and tiotropium 4
• Salmeterol/fluticasone propionate and tiotropium bromide 5
• Tiotropium plus formoterol and salmeterol plus fluticasone 6
• Tiotropium plus fluticasone propionate/salmeterol and tiotropium monotherapy 7

• The results of these studies suggest that the combination of a long-acting beta-agonist (LABA) and a long-acting muscarinic antagonist (LAMA) with or without an inhaled corticosteroid (ICS) may be more effective in improving lung function and quality of life in patients with COPD than either treatment alone.