Extended Exhaled Nitric Oxide Analysis in Interstitial Lung Diseases: A Systematic Review

Area of Science:

• Pulmonary Medicine
• Biomarkers
• Respiratory Physiology

Background:

• Fractional exhaled nitric oxide (FeNO) is a validated biomarker for airway inflammation in asthma.
• Multiple-flows FeNO assessment offers insights into bronchial and alveolar nitric oxide (NO) production.
• Interstitial lung diseases (ILDs) represent a group of peripheral lung disorders with limited specific biomarkers.

Purpose of the Study:

• To review the role of NO in lung fibrosis pathobiology.
• To evaluate the utility of extended FeNO analysis (multiple-flows) in ILD management.
• To explore the potential of FeNO in differential diagnosis, prognosis, and severity assessment of ILDs.

Main Methods:

• Systematic review of published evidence on extended FeNO analysis in ILDs.
• Discussion of NO's role in lung fibrosis.
• Explanation of techniques for measuring bronchial flux of NO (J'awNO) and alveolar concentration of NO (CaNO).

Main Results:

• Multiple-flows FeNO analysis provides reliable measurements of bronchial and alveolar NO.
• Evidence suggests FeNO's potential in differential diagnosis, prognostic evaluation, and severity assessment of ILDs.
• Limited data exist on extended FeNO analysis in common ILD comorbidities.

Conclusions:

• Multiple-flows FeNO analysis, especially CaNO, is a promising tool for ILD diagnostic and prognostic pathways.
• Extended FeNO analysis may enhance the management of patients with ILDs.
• Further research is warranted to fully integrate FeNO into ILD clinical practice.