Title:Clinical Values of Nitric Oxide Parameters from the Respiratory System
Volume: 27
Issue: 42
Author(s): Lauri Lehtimäki, Tuomas Karvonen and Marieann Högman*
Affiliation:
- Department of Medical Sciences, Respiratory, Allergy and Sleep Research, Uppsala University, S-75185 Uppsala,Sweden
Keywords:
Breath test, nitric oxide, mathematical model, pulmonary gas exchange, respiratory system, NO.
Abstract:
Background: Fractional exhaled nitric oxide (FENO) concentration reliably reflects
central airway inflammation, but it is not sensitive to changes in the NO dynamics in the lung
periphery. By measuring FENO at several different flow rates one can estimate alveolar NO
concentration (CANO), bronchial NO flux (JawNO), bronchial wall NO concentration (CawNO)
and the bronchial diffusivity of NO (DawNO).
Objective: We aimed to describe the current knowledge and clinical relevance of NO parameters
in different pulmonary diseases.
Methods: We conducted a systematic literature search to identify publications reporting NO
parameters in subjects with pulmonary or systemic diseases affecting the respiratory tract. A
narrative review was created for those with clinical relevance.
Results: Estimation of pulmonary NO parameters allows for differentiation between central
and peripheral inflammation and a more precise analysis of central airway NO output. CANO
seems to be a promising marker of parenchymal inflammation in interstitial lung diseases and
also a marker of tissue damage and altered gas diffusion in chronic obstructive pulmonary
disease and systemic diseases affecting the lung. In asthma, CANO can detect small airway
involvement left undetected by ordinary FENO measurement. Additionally, CawNO and
DawNO can be used in asthma to assess if FENO is increased due to enhanced inflammatory
activity (increased CawNO) or tissue changes related to bronchial remodelling (altered
DawNO).
Conclusion: NO parameters may be useful for diagnosis, prediction of disease progression
and prediction of treatment responses in different parenchymal lung and airway diseases.
Formal trials to test the added clinical value of NO parameters are needed.