Friday, August 7, 2015

What Exactly Is "Reactive Airways Disease" Anyway?

“I think that she has a component of reactive airways disease,” the doctor said, describing her otherwise healthy 22-year-old patient with a lingering cough and chest tightness after a respiratory tract infection. “That’s why she has this persistent, wheezy-sounding cough. I’m going to prescribe a bronchodilator and some inhaled steroids.”

“Reactive airways disease.” What is that? I think that I know what the doctor means, but it is hard to be sure. She probably means that following a viral respiratory infection, her patient has sensitized, inflamed bronchial tubes, with asthma-like “twitchiness,” that will benefit from anti-asthmatic medications to relax bronchial smooth muscle (bronchodilators) and suppress airway inflammation (inhaled steroids). And maybe she is correct. But I object to the term, “reactive airways disease,” used to describe what is going on in her patient’s bronchial tubes. Here’s why.

Although I agree that the patient has lingering symptoms and probable airway inflammation following her respiratory infection, I wonder does she really have a “disease” that is being diagnosed other than a viral bronchitis? A disease characterized by “reactive” (that is, constricting more easily than usual) airways? Isn’t that asthma? “Reactive airways disease” sounds to me like “Asthma-like,” or “Asthma-light,” or perhaps “Asthma-but-I’m-not-sure.” But medical providers have the tools available that will allow us to determine whether she has asthma or not. Peak flow measurements, spirometry, exhaled nitric oxide concentration, and bronchoprovocation challenge – there are multiple tools at our disposal.

I understand that in children too young to perform pulmonary function testing, in whom transient wheezing (without asthma) is common and asthma can be difficult to diagnose with certainty early on, the term “reactive airways disease” makes sense as a kind of “place holder,” until the presence or absence of asthma becomes clearer. But the patient we are discussing is 22 years old. Does she have asthma or not? I think that we should be as clear as we can about her diagnosis, rather than slip into the vagueness and ambiguity of “reactive airways disease.”

Why send patients home thinking that they have a newly-diagnosed disease to deal with, when what they have is a lingering cough following a viral respiratory infection, maybe associated with transient bronchial hyperresponsiveness, which will improve with time and/or with our medications?

Yes, but what about that wheezy cough, or wheezing when the patient was asked to breathe out forcefully? Doesn’t that point to something more than an ordinary cough following a cold? Maybe, and maybe not. Let’s check her lung function. If it is normal, then the wheezing is probably not due to asthma with its diffuse airway narrowing involving thousands of bronchial tubes but to central or upper airway narrowing as can be seen in healthy individuals on forceful exhalation and cough, when pressures inside the chest tending to compress bronchial tubes are particularly high. On the other hand, if lung function testing demonstrates airflow obstruction, we have made a diagnosis of asthma (not reactive airways disease). As the maxim goes, “not all that wheezes is asthma” … and not all that wheezes is a disease.

Another reason to avoid the expression, “reactive airways disease,” is that it can easily be confused with reactive airways dysfunction syndrome or RADS, an accepted medical term used to describe a form of occupational asthma. Most occupational asthma develops after many weeks and months of exposure to an inciting inhaled irritant or allergen. On occasion, a single, particularly intense or toxic exposure can cause airway injury and hyperreactivity, referred to as reactive airways dysfunction syndrome, in which the sufferer newly develops asthma after the exposure. I’m not sure that reactive airways dysfunction syndrome is ideal terminology either, but it has a clearer definition and has acquired a more precise meaning than reactive airways disease. The term, RADS, will likely stay, whereas in my opinion we can let the expression “reactive airways disease” go when speaking of adults with cough and wheeze.