Exercise Induced Bronchoconstriction: Asthma by Any Other Name
Recently, the American Thoracic Society published new clinical practice guidelines for exercise-induced asthma. This is an important subject, particularly for children and adults who are involved in sports or who exercise regularly (which should, of course, be everyone), and so I will review parts of the guidelines over the next few posts.
One of the documents chief recommendations is that the term “exercise induced asthma” be done away with and replaced with “exercise induced bronchoconstriction or bronchospasm (EIB)”. This recommendation is based on the observation that, although exercise is one of the most common triggers for bronchial narrowing in asthmatics, it also occurs in some athletes (particularly those of the “elite” variety) who have never been diagnosed with or treated for asthma. To use the term “asthma” may therefore be not only inaccurate but also, possible, unfairly stigmatizing. By eliminating the term “asthma” and replacing it with “bronchoconstriction”, the diagnosis can be applied to both asthmatics and non-asthmatics alike.
This symantical nuancing highlights limitations in our current understanding of asthma. It is generally agreed that asthma should be considered a condition characterized by chronic inflammation in the airways. This inflammation is responsible for the phenomenon of airway hyperreactivity, a heightened sensitivity to a variety of environmental triggers including respiratory infections, cigarette smoke, dust, and exercise, which cause reflex tightening of muscles surrounding the airways or bronchospasm. Bronchospasm produces narrowing of the airways and many of the symptoms characteristic of asthma including shortness of breath, wheezing, cough, and sensation of chest tightness.
Also important in the definition of asthma is reversibility. Although the narrowing of the airways from bronchospasm can be severe and even life threatening, it is not permanent, and with proper treatment, the limitations and symptoms associated with an asthma attack can be reversed and lung function will return to normal. In addition, asthma can be a significant problem in a child but remit for a number of years with normal lung functions and only occasional, mild symptoms occurring as a teenager. Under these circumstances, it can be a challenge to answer the question, “do I still have asthma?”
An athlete with EIB has all the characteristics of asthma with the exception of chronicity. When the athlete is not exercising, lung function is normal. However, other tests that are used to diagnose asthma may be just as abnormal as in patients with a diagnosis of asthma.
Because many patients who have had a diagnosis of asthma in the past and who now have infrequent symptoms usually have normal lung function, there may be no measurable difference between a patient with mild asthma and a patient with EIB. And yet under the new American Thoracic Society recommended terminology, EIB is not “asthma”, except when it is.