Offline exhaled nitric oxide in children: chemiluminescence vs.
electrochemical devices
Abstract
Background: Exhaled nitric oxide (eNO) is a noninvasive marker of airway
inflammation that can be measured by the “online” or “offline”
technique. There are few articles that measure “offline” eNO in
children at tidal volume and to our knowledge there is no article that
compares the concordance and correlation between 2 different
technologies measured offline at tidal volume. Objective: is to report
the concordance and correlation of the eNO results obtained with a
chemiluminescence vs. an electrochemical device by the “offline”
technique at tidal volume. Methods: A cross-sectional, observational and
prospective study was conducted in the National Institute of Respiratory
Diseases, Mexico City. Healthy children and those with any lung disease
between 1 and 11 years of age were included. The exhaled air sample was
obtained at tidal volume by attaching a mask with a connection to a
Mylar® bag. Results: 36 children were studied. The average (±SD) age of
the study population was 6 ± 2.6 years; 25% of subjects included were
healthy, and the rest had lung disease. The concordance correlation
coefficient between the two measuring devices was 0.98
(p<0.001), with an average difference of 1.46 ± 3.5 ppb and
95% limits of agreement from -5.3 ppb to 8.3 ppb. The linear regression
model equation for the estimation of eNO was eNO,cl = (eNO,eq· 1.0718)
– 0.1343, (r2 = 0.97) Conclusion: The measurement of eNO by the
“offline” method at tidal volume can be analyzed by electrochemical
devices, and the results are interchangeable with those analyzed by
chemiluminescence technology.