A suitable protocol for measuring alveolar nitric oxide in asthma with differing severity to assess peripheral airways inflammation

Zsófia Lázár, Péter Horváth, Rita Puskás, Gabriella Gálffy, György Losonczy, Ildikó Horváth, András Bikov

Research output: Article

3 Citations (Scopus)

Abstract

Objective: Extended nitric oxide (NO) analysis offers the partitioned monitoring of inflammation in central and peripheral airways. Different mathematical models are used to estimate pulmonary NO dynamics in asthma with variable results and limitations. We aimed to establish a protocol for extended NO analysis in patients with differing asthma severity. Methods: Forty patients with stable asthma and 25 matched control subjects were recruited. Exhaled NO was measured at constant flow rates between 10 and 300 mL/s. Twelve controls performed NO measurements weekly for 4 weeks. Results: The proportions of patients with technically acceptable measurements at 10–30–50–100–150–200–250–300 mL/s exhalation flow rates were 8–58–100–98–98–95–90–80%, respectively. Alveolar NO (CANO) and total flux of NO in the conducting airways (JawNO) were calculated with the linear method from NO values measured at 100–150–200–250 mL/s exhalation flows. The mean intrasubject bias for JawNO and CANO in controls was 0.16 nL/s and 0.85 ppb, respectively. Both JawNO (1.31/0.83–2.97/vs. 0.70/0.54–0.87/nL/s, p < 0.001) and CANO (4.08/2.63–7.16/vs. 2.42/1.83–2.89/ppb, p < 0.001) were increased in patients with asthma compared to controls. In patients, CANO correlated with RV/TLC (r = 0.58, p < 0.001), FEF 25-75% (p = 0.02, r = –0.36) and DL,CO (r = –0.46, p = 0.004). JawNO was not related to lung function parameters. Conclusions: Calculation of alveolar NO concentration with the linear method from values obtained at medium flow rates (100–250 mL/s) is feasible even in asthmatic patients with severe airflow limitation and may provide information on small airways dysfunction in asthma.

Original languageEnglish
Pages (from-to)584-593
Number of pages10
JournalJournal of Asthma
Volume56
Issue number6
DOIs
Publication statusPublished - jún. 3 2019

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Immunology and Allergy
  • Pulmonary and Respiratory Medicine

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