e-NO peak versus e-NO plateau values in evaluating e-NO production in steroid-naive and in steroid-treated asthmatic children and in detecting response to inhaled steroid treatment
M. Silvestri et al., e-NO peak versus e-NO plateau values in evaluating e-NO production in steroid-naive and in steroid-treated asthmatic children and in detecting response to inhaled steroid treatment, PEDIAT PULM, 31(1), 2001, pp. 37-43
Airway nitric oxide (NO) production can be measured by chemiluminescence an
alyzer in children able to perform a single low exhalation. The aim of the
present study was to evaluate whether exhaled NO (e-NO) peaks (first part o
f the exhalation) were as useful as e-NO plateaus (last part of the exhalat
ion) in evaluating e-NO production in asthmatic children and in detecting r
esponses to inhaled steroid treatment. E-NO peak, plateau, and rate of prod
uction values were measured in 100 atopic asthmatic children using a chemil
uminescence analyser. Thirty-seven patients (mean age, 11.1 = 0.7 years) we
re receiving inhaled steroids (flunisolide, 0.8-1 mg daily) or beclomethaso
ne (0.2-0.4 mg daily), while the remaining 63 (mean age, 12.0 +/- 0.4 yrs)
were-steroid naive and treated only with inhaled beta (2)-agonists on an as
-needed basis. Fifteen out of the 63 steroid-naive patients were reevaluate
d after a short course (3 weeks) of inhaled corticosteroid treatment (fluni
solide, 0.8-1 mg daily, or beclomethasone, 0.2-0.4 mg daily).
Regardless of the type of data analysis (peak, plateau, or rate of producti
on), the e-NO Values of the steroid-naive patients were significantly highe
r than those of inhaled steroid-treated patients (P<0.01, each comparison).
Similarly, in the subgroup of steroid-naive patients, the three methods we
re able to detect a decrease in e-NO levels by inhaled steroid therapy (P<0
.001, each comparison). Plotting the difference between e-NO peak and e-NO
plateau values against their average, the peak e-NO concentrations were hig
her than e-NO plateau values. This difference was independent of the absolu
te e-NO concentration. The results of the two types of data analysis seems
to agree more closely in steroid-naive patients than in steroid treated pat
ients, or in the subgroup of steroid-naive patients who received a short co
urse treatment with inhaled steroids, In steroid-treated subjects, the diff
erences were up to five times higher for peak than plateau e-NO values.
These data suggest that both e-NO plateau and e-NO peak values are useful i
n detecting airway NO production in atopic asthmatic children, but they can
not be used interchangeably. Because of possible nasal contamination in e-N
O peak measurement, we prefer e-NO plateau levels for evaluating lower airw
ay e-NO production. (C) 2001 Wiley-Liss. Inc.