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A previously healthy 35-year-old man is evaluated for episodic wheezing, dyspnea, and cough. Two months ago he had an acute episode of cough, dyspnea, wheezing, and chest tightness within minutes of inhaling high concentrations of chlorine gas after an accidental spill at work. At that time he was examined in the emergency department; chest radiograph was reported to be normal and he received a brief course of antibiotic therapy and oral corticosteroids. The patient has no prior history of asthma or allergies and is healthy otherwise. The physical examination is normal. Spirometry shows a forced expiratory volume in 1 second (FEV1) of 90% of predicted; FEV1/FVC is 82%.
Which of the following is the most appropriate next test in this patient's evaluation?
A Bronchoscopy with endobronchial biopsy
B Methacholine challenge test
C Inhalation challenge with increasing concentrations of chlorine
D Spirometry before and after work shift
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Answer and Critique (Correct Answer = B)
The reactive airway dysfunction syndrome (RADS) follows a single, accidental inhalation of high levels of a nonspecific respiratory irritant in patients who typically do not have a history of asthma. Within minutes of exposure, the patient develops cough, wheezing, dyspnea, and chest tightness. Symptoms persist even after exposure has stopped and may last for years, but can also resolve in a few months. The diagnosis is based on history and confirmed by positive methacholine challenge test. Methacholine challenge can be done safely in patients with asthma provided appropriate guidelines are followed and that the FEV1 is greater than 70%. Exposure challenge with chlorine poses unnecessary risk of severe attacks. Bronchial biopsy is not necessary for the diagnosis. Spirometry before and after work shift is not helpful in cases of accidental exposure to irritants because these exposures are not likely to happen on a daily basis and therefore these measurements (which are used in other forms of occupational asthma) are not useful in the diagnosis of RADS.
Key Points
* The reactive airway dysfunction syndrome follows a single, accidental inhalation of high levels of a nonspecific respiratory irritant in patients who typically do not have a history of asthma.
* The diagnosis of the reactive airways dysfunction syndrome is based on history and confirmed by positive methacholine challenge.
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METHACHOLINE AIRWAY CHALLENGE .................................................................FOR REACTIVE AIRWAY DYSFUNCTION SYNDROME
