PhD Scientific Days 2021

CL_V_P: Clinical Medicine V. Posters

Measurements of upper and lower airway nitric oxide in healthy adults

Text of the abstract

Introduction: Elevated lower airway nitrative stress in asthma and COPD can be monitored by measuring exhaled nitric oxide (NO) concentration. Nasal inflammation seems to influence the disease in the lower airways and worsens clinical control. However, nasal NO (nNO) measurement is not widely used to assess upper airway inflammation.

Aims: To evaluate the repeatability and within-subject variations of nNO output (nV̇NO) in healthy adults, and to study its correlation to lower airway NO parameters.

Methods: nV̇NO was measured in healthy non-smokers at baseline (N=27, age: 28±7 years) using NOA280i. Measurements were repeated after 1 hour (N=15), 1 day (N=15) and 1 week (N=17). At baseline, lower airway NO parameters (FeNO, total flux of NO in the conducting airways (JawNO) and alveolar NO concentration (CANO)) were also measured.

Results: Baseline median nV̇NO was 464.8 (IQR=404.0-536.0) nl/min. The mean differences between the baseline and repeated measurements were not significant (p>0.05) i.e., there was no systemic bias at repeated measurements. The coefficients of repeatability (mean: 118.3, IQR=87.8-181.2 nl/min) and variation (mean: 9.1%) were low. The mean within-subject variation was 42.7 nl/min. We found no correlation between nV̇NO and lower airway NO (FENO: p=0.44, JawNO: p=0.39, CANO: p=0.77, respectively).

Conclusions: Our results show that nNO output has good repeatability and an acceptable within-subject variation in healthy adults. NO production in the upper and lower airways might not be related. Our data help establish the minimal clinically important difference in nNO output.

Funding: Supported by the ÚNKP-20-3-I-SE-20 New National Excellence Program of the Ministry for Innovation and Technology from the source of the National Research, Development and Innovation Fund

University and Doctoral School

Semmelweis University, Károly Rácz Doctoral School of Clinical Medicine