Noninvasive testing of lung function and inflammation in pediatric patients with acute asthma exacerbations

There is limited information on performance rates for tests of lung function and inflammation in pediatric patients with acute asthma exacerbations. We sought to examine how frequently pediatric patients with acute asthma exacerbations could perform noninvasive lung function and exhaled nitric oxide (FE(NO)) testing and participant characteristics associated with successful performance.

We studied a prospective convenience sample aged 5-17 years with acute asthma exacerbations in a pediatric emergency department. Participants attempted spirometry for percent predicted forced expiratory volume in 1 second (%FEV(1)), airway resistance (Rint), and FE(NO) testing before treatment. We examined overall performance rates and the associations of age, gender, race, and baseline acute asthma severity score with successful test performance.

Among 573 participants, age was (median [interquartile range]) 8.8 [6.8, 11.5] years, 60% were male, 57% were African-American, and 58% had Medicaid insurance. Tests were performed successfully by the following [n (%)]: full American Thoracic Society-European Respiratory Society criteria spirometry, 331 (58%); Rint, 561 (98%); and FE(NO), 354 (70% of 505 attempted test). Sixty percent with mild-moderate exacerbations performed spirometry compared to 17% with severe exacerbations (p = .0001). Participants aged 8-12 years (67%) were more likely to perform spirometry than those aged 5-7 years (48%) (OR = 2.23, 95% CI: 1.45-3.11) or 13-17 years (58%) (OR = 1.61, 95% CI: 1.00-2.59).

There is clinically important variability in performance of these tests during acute asthma exacerbations. The proportion of patients with severe exacerbations able to perform spirometry (17%) limits its utility. Almost all children with acute asthma can perform Rint testing, and further development and validation of this technology is warranted.