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Thursday, July 24, 2014
Dramatic Changes in Pulmonary Function Test Results
I have a restrictive lung disease and resp muscle weakness verified by Pulmonary Function Tests (MIP 21%, MEP 25% of predicted etc). I have been told in the past that I have mild asthma due to a 15% reversibility after albuterol. I have been treated with advair and albuterol. Yesterday my pulmo did a pre and post spirometry . My numbers actually were worse after the Albuterol. What would cause it to be worse? My doctor took me off the meds as it seems the asthma is gone. Is this common? Also, could this change again in the future? He said if I begin to have symptoms of asthma, I probably would have to go back on the meds. I was just a little baffled and curious. Thanks.
Airway hyperresponsiveness is indeed a hallmark of asthma and is generally defined as an increase in either the FEV1 or FVC of 12% and at least 200 mL after treatment with a bronchodilator such as albuterol. However, there is no one test for asthma and a diagnosis of asthma requires the appropriate clinical symptoms, pulmonary function pattern, and exclusion of other possibilities. While asthmatics have hyperresponsive airways, there are some people who may have airway hyperresponsiveness without having asthma. Asthmatics on regular treatment with a controller medication, such as inhaled steroids, may have less responsiveness after albuterol due to the effect of the medication, which doesn't mean their asthma is gone rather it just indicates the effect of the medication.
Asthma is an episodic disease with symptoms that come and go based on exposure to triggers such as viral infections, environmental allergens, etc. Asthma does not usually "go away" rather it often alternates between symptomatic episodes or periods of good control with few symptoms. Proper medical therapy can ensure the best control and most symptom free days for an asthmatic. People may be tried on different asthma medications to assess the response and determine which is the optimal treatment regimen. In general inhaled corticosteroids are the preferred first line controller medication and short acting beta agonists are given as a rescue medication to only use as needed.
There are case reports of people who have worse lung function after albuterol. In most cases this is a reaction to the stabilizers or other components in the propellant of the meter dose inhaler (MDI) and rarely is a person reacting negatively to the actual drug. This has been seen with the older MDIs that had perfluorocarbon as a main component of the propellant. These MDI's are now being eliminated from the market and it remains to be seen if similar reactions occur with the newer HFA inhalers.
John G Mastronarde, MD
Clinical Professor of Pulmonary, Allergy, Critical Care & Sleep
College of Medicine
The Ohio State University