Exhaled breath condensate pH in the evaluation of asthma

As a marker of inflammation, exhaled breath condensate (EBC) pH may be a useful screening tool in the evaluation of asthma, especially in a military recruit population. To evaluate the utility of EBC pH in the diagnosis of asthma, EBC pH levels were determined in basic military trainees prior to an evaluation for asthma that included a history, physical exam, baseline spirometry, and a methacholine or exercise challenge. Of 86 basic trainees who had symptoms suggestive of asthma and underwent methacholine or exercise challenges, 51 (59.3%) had a positive methacholine or exercise challenge and were diagnosed with asthma. The mean EBC pH of the trainees who were diagnosed with asthma (6.39, range 5.91-6.82), was significantly (p < 0.001) lower than those trainees without asthma (6.64, range 6.34-7.18). There was, however, some overlap of the EBC pH values between the two groups. The measurement of EBC pH did show a significant mean difference between asthmatic and nonasthmatic patients in a military recruit population.