From the Guidelines
For a bronchodilator reversibility test, you should wait 15 minutes after administering a short-acting beta-agonist (like albuterol/salbutamol) or 30 minutes after an anticholinergic bronchodilator (like ipratropium bromide) before performing the post-bronchodilator spirometry. This recommendation is based on the most recent and highest quality study available, which suggests that the waiting period allows the medication sufficient time to reach the airways and achieve maximum bronchodilation 1.
The standard protocol typically involves administering 2.5–5 mg nebulised salbutamol or 5–10 mg terbutaline, with measurements taken before and 15 minutes after administration, or 500 µg nebulised ipratropium bromide, with measurements taken before and 30 minutes after administration 1.
Some key points to consider during the test include:
- The dose of the bronchodilator should be high on the dose/response curve and given by nebuliser to ensure it has been inhaled effectively 1.
- The test is considered positive for reversibility if there's an improvement of at least 12% and 200 mL in either FEV1 or FVC compared to pre-bronchodilator values 1.
- The severity of pulmonary function abnormalities is based on FEV1 % pred, but this may not always accurately predict clinical severity or prognosis for individual patients 1.
- It's essential to remain seated and relaxed while waiting for the test to ensure accurate results.
Overall, the waiting period and standard protocol for the bronchodilator reversibility test are crucial in diagnosing conditions like asthma and other respiratory diseases, and should be followed carefully to ensure accurate results 1.
From the Research
Bronchodilator Reversibility Test Waiting Time
- The waiting time for a bronchodilator reversibility test is typically 15 minutes after administration of the bronchodilator, as seen in a study published in The European respiratory journal 2.
- This study measured forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) before and 15 minutes after 200 μg of salbutamol in 35,628 subjects.
- Another study published in Thorax 3 also used a similar timeframe, measuring spirometric parameters before and after salbutamol and ipratropium bromide sequentially or in combination over 2 months.
- However, the exact waiting time may vary depending on the specific protocol and guidelines being followed.
Factors Affecting Bronchodilator Reversibility
- The response to bronchodilators can be influenced by various factors, including the pre-bronchodilator FEV1 value, as seen in a study published in Thorax 3.
- The study found that the percentage change in FEV1 correlated with pre-bronchodilator FEV1, but the absolute change in FEV1 was independent of the pre-bronchodilator value.
- Another study published in Danish medical bulletin 4 found that the responses to corticosteroids were more spread out and correlated with age, smoking habits, and blood eosinophilia.
Reversibility Criteria
- The criteria for determining bronchodilator reversibility can vary, with different studies using different definitions, such as an increase in FEV1 of 12% and 200 mL 2.
- The American Thoracic Society/GOLD (ATS) and European Respiratory Society (ERS) criteria are also used to classify responses, but these criteria may not always be reliable or predictive of disease progression 3.