Exhaled breath condensate (EBC) collection and exhaled nitric
oxide measurement
EBC was collected by Turbo-Deccs system (Medivac, Parma, Italy).
Approximately 1 ml of EBC was collected and immediately stored at -80℃
for further analysis. Following EBC collection (after 30 minutes of
rest), fractional exhaled nitric oxide (FeNO) was measured according to
published standards by using NIOX MINO Airway Inflammation Monitor
(Aerocrine, Solna, Sweden).