Children with asthma between 7 and 10 years of age who had their fractional exhaled nitric oxide (FeNO) measured using a 6-second exhalation had consistent results that agreed with 10-second exhalation measurements, according to the results of a study published in the Journal of Asthma.

FeNO measurements were taken using a portable electrochemical analyzer. The analyzer had both 6-second and 10-second measurement modes. Results for agreement and repeatability were compared between measurement durations.

Of the 45 participants, 68% were boys and 32% were girls. A total of 43 were able to complete ≥1 FeNO measurement in both the 6- and 10-second modes, and 41 completed 2 measurements in both modes.

Overall means for both modes were 33.59 ppb and 32.46 ppb for the 6- and 10-second modes, respectively. The weighted analysis showed no evidence of systematic bias in measurements, demonstrating agreement between exhalation durations. The mean intrasubject standard deviation for the evaluable population with 2 measurements in both modes was slightly higher but nonsignificant for the 10-second mode (1.828) compared with the 6-second mode (1.380).

“Providing an alternative and feasible option to measure FeNO is important when the children cannot perform a 10-[second] measurement,” the researchers noted. ”[P]hysicians can obtain the valuable information on airway inflammation provided by measuring FeNO using the 6-[second] exhalation mode in most children.”

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Rickard K, Jain N, MacDonald-Berko M. Measurement of FeNO with a portable, electrochemical analyzer using a 6-second exhalation time in 7–10-year-old children with asthma: comparison to a 10-second exhalation [published online November 19, 2018]. J Asthma. doi:10.1080/02770903.2018.1541350