Measuring exhaled nitric oxide in COPD: from theoretical consideration to practical views

Area of Science:

• Respiratory Medicine
• Pulmonology
• Biomarkers

Background:

• Chronic obstructive pulmonary disease (COPD) is often linked to Th1-inflammation, but a subset exhibits Th2-inflammation.
• High fraction of exhaled nitric oxide (FeNO) is a known biomarker for Th2-inflammation in asthma.
• The clinical utility of FeNO measurement in COPD remains under-explored.

Purpose of the Study:

• To review existing evidence supporting FeNO measurement in COPD patients.
• To discuss the potential clinical applications of FeNO in managing COPD.
• To explore the role of FeNO in stable COPD and during exacerbations.

Main Methods:

• Review of scientific literature on nitric oxide production in airways.
• Analysis of FeNO measurements in COPD patients (stable and exacerbation phases).
• Discussion of factors influencing FeNO levels (low vs. high) in COPD.

Main Results:

• FeNO levels tend to increase during COPD exacerbations, regardless of baseline values.
• Current evidence is insufficient to define a universal cutoff for elevated FeNO in COPD.
• Personalized baseline FeNO levels are crucial for interpreting future measurements.

Conclusions:

• Establishing a patient-specific baseline FeNO during stable disease is recommended.
• Future home monitoring of FeNO may enable early detection of COPD exacerbations.
• FeNO holds potential for personalized COPD management and timely intervention.