Sputum induction in severe exacerbations of asthma: safety of a modified method.

Sputum induction with hypertonic saline is one of the most commonly used and reliable noninvasive methods to examine airway inflammation. The safety of induced sputum has been the subject of many reports focusing on stable asthma of any severity and the procedure is regarded as safe [1]. However, data on safety of induced sputum in acute asthma is limited. In a previous small study, we safely induced sputum in 10 patients with severe exacerbations of asthma using a modified method: starting the induction with isotonic saline, followed by the inhalation of hypertonic saline if necessary [2]. Here, we further examined the safety of this method in a larger number of patients.