RT Journal Article SR Electronic T1 Exhaled nitric oxide measurements with dynamic flow restriction in children aged 4–8 yrs JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP 919 OP 924 DO 10.1183/09031936.02.01282002 VO 20 IS 4 A1 M.W.H. Pijnenburg A1 E.T. Lissenberg A1 W. Hofhuis A1 L. Ghiro A1 W.C.J. Hop A1 W.P. Holland A1 J.C. de Jongste YR 2002 UL http://erj.ersjournals.com/content/20/4/919.abstract AB Fractional exhaled nitric oxide concentration (FEno) depends on exhalation flow; however, children often are unable to perform controlled flow procedures. Therefore, a device was developed for off-line FEno sampling, with dynamic flow restriction (DFR). The authors compared off-line with on-line FEno, assessed feasibility, and obtained normal values for FEno in children aged 4–8 yrs. Subjects inhaled nitric oxide (NO)-free air and exhaled into the device, where DFR kept exhalation flow constant at 50 mL·s−1. Dead space air was discarded. Exhaled air was collected in a 150 mL mylar balloon. On-line measurements were performed and values compared with off-line FEno in 19 adult volunteers. Seventy-nine children performed off-line sampling. All samples were analysed with a chemiluminescence NO-analyser. Normal values were obtained in 34 healthy children. There was an excellent correlation between on- and off-line values. Bland and Altman plots showed good agreement between on- and off-line FEno. Seventy-four out of 79 children were able to perform a correct off-line procedure. Geometric mean±sem FEno in healthy children was 4.9±1.2 parts per billion (ppb) for male children and 7.6±1.1 ppb for female children. It can be concluded that off-line fraction of exhaled nitric oxide measurements with dynamic flow restriction are feasible in young children and correspond to on-line values. M.W.H. Pijnenburg was supported by a grant from the Dutch Asthma Foundation and L. Ghiro was supported by a grant of the Italian Nitric Oxide Club (INOC).