Quantitative Assessment and Repeatability of Chlorine in Exhaled Breath Condensate

Background: Airway condition is presumably reflected in epithelial lining fluid (ELF). Exhaled breath condensate (EBC) has been used as a surrogate marker of the composition of ELF. Objectives: This study aimed at assessing the technical repeatability of chlorine measurements in EBC and comparing two separate condensators (Ecoscreen ® and R Tube ™ ) regarding recovery and repeatability. Furthermore, the association between condensate recoveries and variations in the airway status were scrutinized. Methods: EBC was collected using two condensators from 10 healthy volunteers. In addition, 13 asthmatic patients produced EBC with or without an added resistance of 5 cm H 2 O (Res5), applied to the outflow tract of Ecoscreen. All tests were done in random order. Chlorine levels (analyzed by a coulometric technique) in EBC served as a tool for investigation. Results: Chlorine was measurable in all samples. The coefficient of repeatability of chlorine measurements was