Postbronchodilator

Postbronchodilator refers to measurements or results obtained after administration of a bronchodilator during pulmonary function testing. It is most commonly used in spirometry to assess the reversibility of airway obstruction.

In practice, baseline spirometry is performed, followed by administration of a bronchodilator (typically an inhaled short-acting agent such as albuterol/salbutamol). After a standard waiting period, usually about 10 to 15 minutes, spirometry is repeated. The postbronchodilator results are compared with the pre-bronchodilator values to determine the degree of reversibility.

Interpretation commonly uses a criterion that an improvement in FEV1 (forced expiratory volume in one second) of at least 12% and at least 200 milliliters from baseline indicates a positive postbronchodilator response. Some guidelines allow for age- or context-specific adjustments, so exact criteria may vary. A substantial postbronchodilator response supports a diagnosis of reversible airway obstruction, as often seen in asthma, whereas a minimal or absent response is more typical of fixed obstruction such as some cases of COPD.

Clinical use includes distinguishing asthma from COPD, guiding treatment decisions, and evaluating disease control or medication effectiveness. Postbronchodilator testing is also used in research and in certain occupational health assessments. Limitations include dependence on patient effort during spirometry, the specific bronchodilator and dose used, and that reversibility is not exclusive to one disease.