A suitable protocol for measuring alveolar nitric oxide in asthma with differing severity to assess peripheral airways inflammation. (3rd June 2019)

• Record Type: Journal Article
• Authors: Lázár, Zsófia; Horváth, Péter; Puskás, Rita; Gálffy, Gabriella; Losonczy, György; Horváth, Ildikó; Bikov, András
• Is Part Of: Journal of asthma. Volume 56:Number 6(2019)
• Page Start: 584
• Page End: 593
• Publication Date: 2019-06-03
• Subjects: Airway inflammation -- exhaled biomarker -- extended nitric oxide analysis -- disease monitoring -- severe asthma; Asthma -- Periodicals; 616.238005
• DOI: 10.1080/02770903.2018.1477957
• Languages: English
• ISSNs: 0277-0903

Abstract

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 ( C ANO) and total flux of NO in the conducting airways ( J awNO) were calculated with the linear method from NO values measured at 100–150–200–250 mL/s exhalation flows. The mean intrasubject bias for J awNO and C ANO in controls was 0.16 nL/s and 0.85 ppb, respectively. Both J awNO (1.31/0.83–2.97/vs. 0.70/0.54–0.87/nL/s, p < 0.001) and C ANO (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, C ANO correlated with RV/TLC ( r = 0.58, p < 0.001), FEF25-75% ( p = 0.02, r = –0.36) and D L, CO ( r = –0.46, p = 0.004). J awNO 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.