RT Journal Article SR Electronic T1 Comparison of single-breath and tidal breathing exhaled nitric oxide levels in infants JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP 369 OP 372 DO 10.1183/09031936.04.00084604 VO 23 IS 3 A1 P.J. Franklin A1 S.W. Turner A1 R.C. Mutch A1 S.M. Stick YR 2004 UL http://erj.ersjournals.com/content/23/3/369.abstract AB The aim of this study was to compare two different methods, tidal breathing (TB) and single-breath (SB), for measuring fractional exhaled nitric oxide (FENO) in infants. FENO was measured in 71 infants with either recurrent wheeze (n=32), recurrent cough (n=16) or no symptoms (healthy, n=23) using both methods. For TB measurements five breaths were collected into a gas sampling bag (off-line reservoir sampling). The SB method was modified from the raised volume rapid thoraco-abdominal technique. Agreement between the two methods was investigated and both methods were used to compare FENO in infants with and without symptoms. Flow dependence of SB FENO was demonstrated using two expiratory flows (11 and 40 mL·s−1). There was a moderate correlation (r=0.60) but poor agreement between levels using the TB and SB methods. A significant difference in FENO between healthy children and children with wheeze was found using the SB but not the TB method. Due to lower expiratory flow and reduced nasal nitric oxide contamination the single-breath technique may be more sensitive than the tidal breathing method for detecting differences in exhaled nitric oxide between infants with and without respiratory symptoms. This study was funded by the National Health and Medical Research Council. The Seivers NOA 280 nitric oxide analyser was bought using an unrestricted grant from Glaxo-Wellcome, Australia.