Sampling of exhaled nitric oxide in children: end-expiratory plateau, balloon and tidal breathing methods compared

Abstract

Personally measured weekly exposure to NO 2 and respiratory health among preschool children. K. Mukala, J. Pekkanen, P. Tiittanen, S. Alm, R.O. Salonen, J. Tuomisto. #ERS Journal Ltd 1999. ABSTRACT: Nitrogen dioxide is known as a deep lung irritant. The aim of this study was to find out whether the relatively low ambient air NO 2 concentrations in the northern city of Helsinki had an impact on the respiratory health of children.The association between personal exposure to ambient air NO 2 and respiratory health was investigated in a 13-week follow-up study among 163 preschool children aged 3±6 yrs. Personal weekly average exposure to NO 2 was measured by passive diffusion samplers attached to the outer garments. Symptoms were recorded daily in a diary by the parents. Among 53 children, peak expiratory flow (PEF) was measured at home in the mornings and evenings. The association between NO 2 exposure and respiratory symptoms was examined with Poisson regression.The median personal NO 2 exposure was 21). An increased risk of cough was associated with increasing NO 2 exposure (risk ratio=1.52; 95% confidence interval 1.00±2.31). There was no such association between personal weekly NO 2 exposure and nasal symptoms, but a nonsignificant negative association was found between the exposure and the weekly average deviation in PEF.In conclusion, even low ambient air NO 2 concentrations can increase the risk of respiratory symptoms among preschool children. Eur Respir J 1999; 13: 1411±1417.

Exhaled nitric oxide measurements with dynamic flow restriction in children aged 4-8 yrs

“…Correlations of different on-and off-line sampling techniques have been reported in the literature [7,[11][12][13][14]. Several authors found an excellent correlation between on-and off-line values; however, agreement between both methods differed in different studies.…”

“…On the other hand, exhalation flow cannot easily be controlled and it is difficult to prevent nasal contamination adequately, leading to increased variation in FENO values. Uncontrolled single exhalations against a resistance are easy to perform and reproducible even in young children, and there is no need for expensive or complicated equipment [7,14,16]. However, in the absence of flow control, FENO values may vary and be unsuitable to monitor individual patients.…”

“…Several groups described different off-line techniques for sampling exhaled NO [7,[11][12][13][14][15][16][17][18][19]. These include tidal breathing techniques and uncontrolled or controlled single exhalations into a reservoir.…”

“…Hence, ATS guidelines recommend measurements during a single, slow exhalation with constant, low flow. However, 4-8-yr-old children are often unable to perform the required controlled flow procedures needed for standardised sampling [6,7]. In children unable to cooperate, tidal breathing methods or exhalations with uncontrolled flow have been used, but these are ill standardised and allow for contamination with ambient and nasal NO [3].…”

Head-to-head comparison of single-breath and tidal-breath exhaled nitric oxide measurements

“…For this reason, simpler but less standardized techniques have been introduced in an attempt to overcome the poor compliance of children, including tidal-breath eNO measurements (eNO TB ) with or without flow control, and offline reservoir sampling (1,(11)(12)(13). Unfortunately, these do not provide accurate data because they have some methodological drawbacks, such as the use of uncontrolled expiratory flow and nasal NO contamination (1).…”