THE EFFECT OF INHALED NITRIC-OXIDE IN PEDIATRIC ASTHMA

Nitric oxide (NO) appears to play an important role in regulating seve ral biologic functions in the lung, including modulation of pulmonary arterial and bronchial smooth muscle tone. Recent studies have shown t hat relatively high concentrations of inhaled NO reduce the bronchocon strictor effect of methacholine in animal models. This raises the poss ibility that NO inhalation might have therapeutic poten- tial as an al ternative bronchodilator. Although investigation of this potential in adults with airway reactivity or bronchial asthma has been reported, d ata are lacking on the role of NO in the pediatric asthma population. We therefore performed spirometry on 12 children with asthma (mean age 11.1 yrs) at baseline (B), immediately after inhaling 40 ppm NO (NO-1 ), 10 min after inhaling NO (NO-10), and after inhalation of a standar d beta(2)-agonist, albuterol (A). Baseline pulmonary functions (% pred icted +/- SEM) were FVC of 103.2 +/- 5.6, FEV(1) of 82.2 +/- 3.3, FEFm ax of 97.0 +/- 3.6, and FEF25-75% of 53.5 +/- 3.3. There were no stati stically significant differences between baseline and NO-1 or NO-10 be tween any of the four pulmonary function parameters measured. Inhaled albuterol, however, resulted in significant improvement (% predicted /- SEM) in FVC to 109.8 +/- 3.5, FEV(1) to 99.7 +/- 2.9, FEFmax to 106 .5 +/- 5.1, and FEF25-75% to 84.4 +/- 6.4 compared with the baseline a nd NO inhalation groups. We conclude that NO inhaled at 40 ppm has no apparent bronchodilatory effect in pediatric subjects with asthma and mild airways disease. The clinical application of this gas as a therap eutic modality under these conditions is questionable.