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 (SpO ) 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 FEV (PC ).

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.

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.

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: 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.