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RESEARCH PRODUCT

The effect of different periods of argon deaeration on exhaled breath condensate pH.

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Exhaled breath condensate (EBC) pH has been considered as a biomarker of airway inflammation in asthma. However, little information is available on the duration of argon deaeration required to achieve a stable pH in EBC samples.To identify differences in EBC pH after argon deaeration for 2, 4, and 8 min.EBC pH was determined in EBC samples from 48 subjects with allergic rhinitis (11 asthmatics) and 14 healthy volunteers without deaeration and after argon deaeration for 2, 4, and 8 min.The mean (95% CI) pH values obtained from samples analyzed after 4 min [7.66 (7.52-7.80)] and 8 min [7.70 (7.55-7.85)] of argon deaeration were significantly less acidic (p.001) than those identified after 2 min of deaeration [7.53 (7.40-7.66)]; differences between pH values at 4 and 8 min were not significant. Furthermore, changes in EBC pH of nondeaerated samples after 4 and 8 min of deaeration were significantly greater than those after 2 min, the mean difference being 0.11 (95% CI, 0.02-0.20, p.05) and 0.13 (95% CI, 0.04-0.22, p.01), respectively; differences between changes at 4 and 8 min were not significant.Stabilization of EBC pH is achieved after argon deaeration for 4 min. Therefore, this deaeration period may be recommended instead of the 7-8 min used in several studies.