The post bronchodilator test (Post BD), also commonly referred to as a reversibility test, is a test that utilizes

spirometry Spirometry (meaning ''the measuring of breath'') is the most common of the pulmonary function tests (PFTs). It measures lung function, specifically the amount (volume) and/or speed (flow) of air that can be inhaled and exhaled. Spirometry is he ...

to assess possible reversibility of bronchoconstriction in diseases such as

asthma Asthma is a long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wheezing, cou ...

Indications

This procedure is indicated in the diagnosis and follow-up of asthma, and in the differentiation between asthma and

COPD Chronic obstructive pulmonary disease (COPD) is a type of progressive lung disease characterized by long-term respiratory symptoms and airflow limitation. The main symptoms include shortness of breath and a cough, which may or may not produce mu ...

Procedure

An initial

is performed to assess the patient's native respiratory status. You will be asked to take a deep breath and then blow into the mouthpiece of the spirometer as hard as you can. This is a baseline measurement. A dose of

bronchodilator A bronchodilator or broncholytic (although the latter occasionally includes secretory inhibition as well) is a substance that dilates the bronchi and bronchioles, decreasing resistance in the respiratory airway and increasing airflow to the lun ...

medication is administered by means of inhaler or nebulizer (such as 400mcg of

salbutamol Salbutamol, also known as albuterol and sold under the brand name Ventolin among others, is a medication that opens up the medium and large airways in the lungs. It is a short-acting β2 adrenergic receptor agonist which works by causing rel ...

(also known as albuterol)). You will wait about 15 minutes and then the spirometry is repeated.{{Cite web, title = Bronchodilator Reversibility Testing - Online Medical Encyclopedia - University of Rochester Medical Center, url = https://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=56&ContentID=DM118, website = www.urmc.rochester.edu, access-date = 2016-02-23 An increase i
FEV1
(or forced expiratory volume in the first second of a forced exhalation) of >200ml is considered a positive result. Bear in mind, however, that this number does not apply to children, and that it can differ depending on the patient's native result; small patient's with

pulmonary fibrosis Pulmonary fibrosis is a condition in which the lungs become scarred over time. Symptoms include shortness of breath, a dry cough, feeling tired, weight loss, and nail clubbing. Complications may include pulmonary hypertension, respiratory failu ...

restrictive lung disease Restrictive lung diseases are a category of extrapulmonary, pleural, or parenchymal respiratory diseases that restrict lung expansion, resulting in a decreased lung volume, an increased work of breathing, and inadequate ventilation and/or oxygenat ...

etc. will have a measurably lower FEV1 than healthy average-sized adults. This can give a false positive result of the test.

References

Pulmonary function testing