ABSTRACT
INTRODUCTION: Exhaled nitric oxide (FE(NO)) may be a biomarker for airway eosinophilia and of use in the management of childhood asthma. Caffeine ingestion has been associated with changes in FE(NO) concentration in adults. The present study tested the hypothesis that ingestion of a caffeine-containing cola drink will increase FE(NO) in asthmatic children. METHODS: Exhaled NO was measured in children with asthma before, 30 and 60 min after taking a cola drink containing 0.7 mg/kg caffeine. Intrasubject changes in FE(NO) and flow independent NO parameters were determined including bronchial wall NO flux (J'awNO). RESULTS: Eleven children with asthma were recruited, 10 were prescribed inhaled corticosteroids and 9 were skin prick positive. The median [interquartile range, IQR] FE(NO) at baseline was 47 parts per billion [9,64] and this rose to 56 ppb [11, 66] after 30 min and returned to 46 ppb [9, 62] after 60 min, Friedman's test P = 0.003. J'awNO rose from a median [IQR] 2,843 nl/sec [356, 4,247] at baseline to 3,304 nl/sec [479, 4,387] after 30 min and returned to 2,937 nl/sec [356, 4,153] after 60 min, Freidman's test P = 0.003. There was no significant change in other flow independent NO parameters. CONCLUSIONS: Ingestion of a caffeine-containing cola drink was associated with a modest and transient rise in FE(NO) which is mostly explained by increased NO production in the proximal airways. Ingestion of a caffeine-containing cola drink may result in clinically relevant acute changes in FE(NO) for children with asthma.
