Independent Information of Nonspecific Biomarkers in Exhaled Breath Condensate

Background: Exhaled breath condensate (EBC) has been used for
diagnosing and monitoring respiratory disorders. For clinical
purposes the assessment of easy-to-obtain nonspecific markers seems
particularly interesting. Objectives: As these measures are related
to each other, our objective was to extract the independent
information in global EBC markers across a range of respiratory
disorders. Methods: EBC was collected from patients with asthma (n
= 18), chronic obstructive pulmonary disease (n = 17), and cystic
fibrosis (n = 46), as well as from lung transplant (LTX) recipients
(n = 14) and healthy controls (n = 26). Samples were assessed for
electrical conductivity, ammonia, pH, and nitrite/nitrate. pH was
measured after both deaeration with argon and CO(2)
standardization. Additionally, the fraction of exhaled nitric oxide
(FE(NO)) was assessed. Factor analysis was applied to identify
major factors concerning these measures. Results: Three independent
factors were detected; the first comprised conductivity, ammonia,
and pH, especially when standardized using CO(2), the second
nitrite/nitrate, and the third FE(NO). Conductivity and ammonia
were highly correlated (r = 0.968; p < 0.001). FE(NO) provided
independent information mainly in asthma. The nonspecific EBC
markers showed considerable overlap between patient groups and
healthy subjects. However, conductivity, ammonia, pH standardized
for CO(2) and nitrite/nitrate were increased in LTX recipients
compared to healthy controls (p < 0.05 each). Conclusions: A
panel of nonspecific easy-to-obtain exhaled breath markers could be
reduced to 3 independent factors. The information content of
conductivity, ammonia, and pH after CO(2) equilibration appeared to
be similar, while FE(NO) was independent. The increased levels of
these biomarkers in LTX might indicate a potential for their use in
these patients. Copyright (C) 2010 S. Karger AG, Basel