Changes in exhaled nitric oxide levels after bronchial allergen challenge.
BACKGROUND
Fractional exhaled nitric oxide (FeNO) is a marker of inflammation of the airways accompanying changes in the clinical condition of asthma. Allergen exposure has been associated with a delayed elevation of FeNO. The aim of this study was to assess airway inflammation with FeNO measurements during bronchial allergen challenge (BAC), and to determine the diagnostic performance of FeNO changes.


METHODS
Thirty-four patients with asthma and sensitization to inhalant allergens were studied. BAC with common or high-molecular-weight occupational aeroallergens was performed. FeNO was measured before and 24 h after BAC. Receiver operating characteristics curve was built to assess the sensitivity and specificity of increase in FeNO levels associated with BAC outcome.


RESULTS
In 21 patients (61.76%) a positive asthmatic reaction (responders) was observed. A significant increase in postchallenge FeNO was observed in this group of patients compared to the group of nonresponders. A median increase (FeNO postchallenge-FeNO prechallenge) of 14.0 ppb was observed in the group of responders, whereas a -1.0 ppb change was attained in the nonresponder group (P < 0.001). The cutoff point providing maximal sensitivity and specificity for %ΔFeNO after BAC was 12%. This change in FeNO levels has a sensitivity of 0.81 and a specificity of 0.92 for predicting a positive outcome in the BAC.


CONCLUSIONS
FeNO measurements can be used as a surrogate of airway inflammation accompanying the asthmatic reaction induced by BAC. FeNO measurements may be a useful and reliable tool in the monitoring and interpreting specific bronchial challenge test with allergens.
Department of Allergy, Hospital La Paz Health Research Institute, IdiPAZ, Madrid, Spain. m.pedrosa.d@gmail.com
María
M
Pedrosa
Pilar
P
Barranco
Valentín
V
López-Carrasco
Santiago
S
Quirce
D000328:Adult; D001249:Asthma / Q000150:complications*; D001944:Breath Tests; D001985:Bronchial Provocation Tests; D004804:Eosinophils; D045853:Exhalation; D006801:Humans; D007249:Inflammation / Q000150:complications* / Q000175:diagnosis*; D009569:Nitric Oxide / Q000032:analysis*; D012372:ROC Curve; D018709:Statistics, Nonparametric; D055815:Young Adult
D009569:Nitric Oxide