Exhaled Nitric Oxide and Airway Caliber in Children With Asthma

Previous studies have shown that a deep inhalation (DI) would increase airway caliber in normal subjects. Whereas in asthmatics with spontaneous bronchoconstriction (obstruction of the airway), DI was shown to worsen airway obstruction. The mechanism for this variability in response to DI is not well-understood, but seems to be a key in understanding the pathophysiology of the disease, and possibly in the development of an effective therapy. Air way inflammation resulting in airway wall thickening and peribronchial edema is thought to play a role how the airway responds to deep inhalation. This study assess if reduction in airway inflammation (as measured by level of exhaled NO)results in optimization of the bronchodilator response to deep inhalation

Inclusion criteria

• Age: > 6 years at age of screening.
• Physician diagnosed asthma
• Elevated exhaled NO at initial evaluation (>25ppb)
• Be able to reproducibly perform DI maneuvers and all other pulmonary function testing
• Be clinically stable for at least 2 weeks prior to screening with no evidence of acute upper or lower respiratory infection or current pulmonary exacerbation.
• Has not been on inhaled or oral steroid for at least 4 weeks prior to enrollment in the study.
• Parent/child willingness to enroll in the study and provide written informed consent.
• Be able to present for the required study visits.

Exclusion criteria

• Chest wall or spinal column deformity; known cardiac, neuromuscular, or other chronic diseases
• Use of beta agonist, theophylline, leukotriene receptor antagonists, or caffeine-containing soft drinks 12 hr prior to the study.
• Use of inhaled steroid in the past 4 weeks.
• Respiratory infection or asthma exacerbation in the previous 2 weeks