Measuring exhaled nitric oxide in infants during tidal breathing: methodological issues

Area of Science:

• Pediatric Allergy and Immunology
• Respiratory Medicine
• Biomarkers

Background:

• Fractional exhaled nitric oxide (FeNO) is a potential biomarker for allergic airway inflammation in children.
• Standardized methods for measuring FeNO in infants using tidal breathing (TB) are lacking.
• Infant FeNO measurement may aid in early identification of children at risk for allergic diseases.

Purpose of the Study:

• To investigate methodological factors affecting tidal breathing FeNO measurements in infants.
• To assess the feasibility of using TB FeNO for identifying infants at risk of allergic disease.
• To compare TB FeNO levels in infants with and without wheeze.

Main Methods:

• Investigated effects of ambient NO, breathing route (oral/nasal), sedation, and tidal expiratory flow on TB FeNO.
• Measured TB FeNO in 88 infants, comparing those with and without wheeze.
• Analyzed data for significant differences and correlations with age and clinical factors.

Main Results:

• Ambient NO >5 ppb significantly altered FeNO readings.
• Sedation significantly impacted FeNO levels (P < 0.001).
• TB FeNO decreased with increasing tidal flow (P < 0.001) and increased with age (P = 0.002).
• No significant difference in FeNO between healthy and wheezy infants, but elevated levels in those with eczema (P = 0.014).

Conclusions:

• Significant methodological limitations exist for measuring TB FeNO in infants.
• Factors like ambient NO, sedation, and expiratory flow require careful control.
• Further standardization is needed before TB FeNO can be reliably used in infant allergy risk assessment.