PT  - JOURNAL ARTICLE
AU  - J. Vaughan
AU  - L. Ngamtrakulpanit
AU  - T.N. Pajewski
AU  - R. Turner
AU  - T-A. Nguyen
AU  - A. Smith
AU  - P. Urban
AU  - S. Hom
AU  - B. Gaston
AU  - J. Hunt
TI  - Exhaled breath condensate pH is a robust and reproducible assay of airway acidity
AID  - 10.1183/09031936.03.00038803
DP  - 2003 Dec 01
TA  - European Respiratory Journal
PG  - 889--894
VI  - 22
IP  - 6
4099  - http://erj.ersjournals.com/content/22/6/889.short
4100  - http://erj.ersjournals.com/content/22/6/889.full
SO  - Eur Respir J2003 Dec 01; 22
AB  - Exhaled breath condensate (EBC) pH is low in several lung diseases and it normalises with therapy. The current study examined factors relevant to EBC pH monitoring. Intraday and intraweek variability were studied in 76 subjects. The pH of EBC collected orally and from isolated lower airways was compared in an additional 32 subjects. Effects of ventilatory pattern (hyperventilation/hypoventilation), airway obstruction after methacholine, temperature (−44 to +13°C) and duration of collection (2–7 min), and duration of sample storage (up to 2 yrs) were examined. All samples were collected with a disposable condensing device, and de-aerated with argon until pH measurement stabilised. Mean EBC pH (n=76 subjects, total samples=741) was 7.7±0.49 (mean±sd). Mean intraweek and intraday coefficients of variation were 4.5% and 3.5%. Control of EBC pH appears to be at the level of the lower airway. Temperature of collection, duration of collection and storage, acute airway obstruction, subject age, saliva pH, and profound hyperventilation and hypoventilation had no effect on EBC pH. The current authors conclude that in health, exhaled breath condensate pH is slightly alkaline, held in a narrow range, and is controlled by lower airway source fluid. Measurement of exhaled breath condensate pH is a simple, robust, reproducible and relevant marker of disease. J. Hunt, B. Gaston and J. Vaughan are minority shareholders in Respiratory Research Inc., the manufacturer of the breath condensate collection devices used for all samples collected in this study. Additionally J. Vaughan is employed part-time by this company.