Spirometry effects on conventional and multiple flow exhaled nitric oxide in children

Abstract

Objective: Clinical and research settings often require sequencing multiple respiratory tests in a brief visit. Guidelines recommend measuring the concentration of exhaled nitric oxide (FeNO) before spirometry, but evidence for a spirometry carryover effect on FeNO is mixed. Only one study has investigated spirometry carryover effects on multiple flow FeNO analysis. The objective of this study was to evaluate evidence for carryover effects of recent spirometry on three exhaled NO summary measures: FeNO at 50 ml/s, airway wall NO flux [J′_awNO] and alveolar NO concentration [C_ANO] in a population-based sample of schoolchildren. Methods: Participants were 1146 children (191 with asthma), ages 12–15, from the Southern California Children’s Health Study who performed spirometry and multiple flow FeNO on the same day. Approximately, half the children performed spirometry first. Multiple linear regression was used to estimate differences in exhaled NO summary measures associated with recent spirometry testing, adjusting for potential confounders. Results: In the population-based sample, we found no evidence of spirometry carryover effects. However, for children with asthma, there was a suggestion that exhaled NO summary measures assessed ≤6 min after spirometry were lower (FeNO: 25.8% lower, 95% CI: −6.2%, 48.2%; J′_awNO: 15.1% lower 95% CI: −26.5%, 43.0%; and C_ANO 0.43 parts per billion lower, 95% CI: −0.12, 0.98). Conclusions: In clinical settings, it is prudent to assess multiple flow FeNO before spirometry. In studies of healthy subjects, it may not be necessary to assess FeNO first.

• Alveolar nitric oxide
• asthma
• bronchial nitric oxide
• pulmonary function test
• spirometry

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper. This work was supported by the National Heart, Lung and Blood Institute (grants 5R01HL61768 and 5R01HL76647); the Southern California Environmental Health Sciences Center (grant 5P30ES007048) funded by the National Institute of Environmental Health Sciences; the Children’s Environmental Health Center (grants 5P01ES009581, R826708-01 and RD831861-01) funded by the National Institute of Environmental Health Sciences and the Environmental Protection Agency; the National Institute of Environmental Health Sciences (grants 5P01ES011627, 1R01ES023262-01, 1K22ES022987); the James H. Zumberge Research and Innovation Fund, and the Hastings Foundation.