Exhaled nitric oxide (eNO) is elevated in asthmatics and is a purported marker of airway inflammation. The bronchodilator response (BDR) has also been shown to correlate with markers of airway inflammation, including eNO at 50 ml/sec (FENO,50) which is comprised of NO from both the proximal and distal airways. Using eNO at multiple flows and a two-compartment model of NO exchange, the eNO signal can be partitioned into its proximal [J'awNO (nl/sec)] and distal contributions [CANO (ppb)].We hypothesized that theBDRreflects the inflammatory status of the larger airways with smooth muscle, and thuswould correlate with J'awNO. In 179 predominantly (95%) Hispanic children with mild asthma (69 steroid naïve), and 21 non-asthmatic non-atopic controls, spirometry andeNOat multiple flowswere measured prior and 10 min following inhalation of albuterol. A trumpet-shaped axial diffusion model of NO exchange was used to characterize J'awNO and CANO. The BDR correlated moderately (r=0.44) with proximal airway NO (J'awNO), but weakly (r=0.26) with distal airway/alveolar NO (CANO), and only in inhaled corticosteroid naïve asthmatics. A BDR cut point as low as ≥8% had a positive predictive value of 83% for predicting an elevated J'aw NO or FENO,50. We conclude that the BDR reflects inflammation in the large airways, and may be an effective clinical tool to predict elevated large airway inflammation.
- Nitric oxide
- Pulmonary function
ASJC Scopus subject areas
- Pediatrics, Perinatology, and Child Health
- Pulmonary and Respiratory Medicine