Fractional exhaled nitric oxide in children with acute exacerbation of asthma.

OBJECTIVE To determine whether fractional exhaled nitric oxide (FENO) has a utility as a diagnostic or predictive maker in acute exacerbations of asthma in children. DESIGN Analysis of data collected in a pediatric asthma cohort. SETTING Pediatric Chest Clinic of a tertiary care hospital. METHODS A cohort of children with asthma was followed up every 3 months in addition to any acute exacerbation visits. Pulmonary function tests (PFT) and FENO were obtained at all visits. We compared the FENO values during acute exacerbations with those at baseline and those during the follow up. RESULTS 243 asthmatic children were enrolled from August 2009 to December 2011 [mean (SD) follow up - 434 (227) days]. FENO during acute exacerbations was not different from FENO during follow up; however, FENO was significantly higher than personal best FENO during follow up (P < 0.0001). FENO during acute exacerbation did not correlate with the severity of acute exacerbation (P=0.29). The receiver operating characteristics curve for FENO as a marker for acute exacerbation had an area under the curve of 0.59. Cut-off of 20 ppb had a poor sensitivity (44%) and specificity (68.7%) for acute exacerbation. CONCLUSIONS FENO levels during acute exacerbation increase from their personal best levels. However, no particular cut off could be identified that could help in either diagnosing acute exacerbation or predicting its severity.