Wheeze is an unreliable endpoint for bronchial methacholine challenges in preschool children.

BACKGROUND: Onset of wheeze is the endpoint often used in the determination of a positive bronchial challenge test (BCT) in young children who cannot perform spirometry. We sought to assess several clinical endpoints at the time of a positive BCT in young children with recurrent wheeze compared to findings in school-aged children with asthma. METHODS: Positive BCT was defined in: (1) preschool children (n = 22) as either persistent cough, wheeze, fall in oxygen saturation (SpO2 ) of ≥5%, or ≥50% increase in respiratory rate (RR) from baseline; and (2) school-aged children (n = 22) as the concentration of methacholine (MCh) required to elicit a 20% decline in FEV1 (PC20 ). RESULTS: All preschool children (mean age 3.4 years) had a positive BCT (median provocative MCh concentration 1.25 mg/ml [IQR, 0.62, 1.25]). Twenty (91%) school-aged children (mean age 11.3 years) had a positive BCT (median PC20 1.25 mg/ml [IQR, 0.55, 2.5]). At the time of the positive BCT, the mean fall in SpO2 (6.9% vs. 3.8%; p = .001) and the mean % increase in RR (61% vs. 22%; p < .001) were greater among preschool-aged than among school-aged children. A minority of children developed wheeze at time of positive BCT (23% preschool- vs. 15% school-aged children; p = .5). CONCLUSIONS: The use of wheeze as an endpoint for BCT in preschool children is unreliable, as it rarely occurs. The use of clinical endpoints, such as ≥25% increase in RR or fall in SpO2 of ≥3%, captured all of our positive BCT in preschool children, while minimizing undue respiratory distress.

Pediatric asthma.

Asthma is one of the most common chronic illnesses affecting children. However, distinguishing true asthma from recurrent respiratory symptoms is often a challenge for primary care providers. Many risk factors can help predict persistent disease, including presence of allergies or eczema, family history, symptoms apart from obvious infection, and the severity of previous episodes. Because neither cure nor prevention is currently a viable option, the treatment is aimed at minimizing symptoms and maximizing asthma control.

Exhaled nitric oxide.

Exhaled nitric oxide (FENO) is a noninvasive easily measurable biomarker that is proving to be an excellent surrogate for eosinophilic inflammation in the lungs of patients who have asthma. Although large-scale normative data are still awaited, preliminary studies have shown FENO to be helpful in diagnosing and assessing severity and control for asthma. FENO levels have also proven helpful in diagnosing and managing several other inflammatory lung diseases.

Exhaled nitric oxide.

Nitric oxide (NO) is now considered an important biomarker for respiratory disease. Studies have confirmed that the fractional concentration of exhaled nitric oxide (FENO) is elevated in the airways of patients who have asthma in comparison with controls. The level of FENO correlates well with the presence and level of inflammation, and decreases with glucocorticoid treatment. NO has potential to be used not only as a diagnostic aid but also as a management tool for assessing severity, monitoring response to therapy, and gaining control of asthma symptoms. This article reviews the biology of NO and its role in respiratory disease.

Exhaled nitric oxide: a test for diagnosis and control of asthma?

The fractional concentration of nitric oxide (FE(NO)) in exhaled breath is a noninvasive marker of airway inflammation in asthma. The precise role of FE(NO) in the asthma management algorithm has not been defined. However, there are compelling data for use of FE(NO) for diagnosing asthma, assessing control and severity, titrating inhaled corticosteroids, and detecting ongoing airway inflammation. This article reviews the biology of nitric oxide in airway pathology and its role in asthma.