Airway hyperresponsiveness to mannitol and methacholine and exhaled nitric oxide in children with asthma.

Objective: Asthma is characterized by airway hyperresponsiveness (AHR), inflammation, and obstruction. AHR to stimuli that indirectly cause bronchial smooth muscle (BSM) contractions via release of endogenous mediators is thought to better reflect airway inflammation than AHR to stimuli that act directly on BSM. Fractional exhaled nitric oxide (FeNO) is a useful parameter for noninvasive clinical airway inflammation assessments.