Measurement of fractional exhaled nitric oxide
FeNO was measured using a handheld electrochemical analyzer (NIOX
MINO®; Aerocrine AB, Sweden) according to the 2005
American Thoracic Society/European Respiratory Society (ATS/ERS)
recommendations for standardized single-breath online
measurement.18 Children were prevented from eating,
drinking, and exercising at least 1 hour before the FeNO measurement;
nitrate or nitrate-containing foods were avoided the night prior to
testing.