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 ...

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, c ...

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 ...

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 l ...

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 fail ...

, restrictive lung disease 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