The role of FENO and spirometry in the evaluation of obstruction in pediatric asthma.

Introduction: The fractional exhaled nitric oxide concentration (FENO) is used as a noninvasive biomarker for asthmatic inflammation. The role in establishing an asthma diagnosis is still under research. Spirometry remains the main investigation for the diagnosis and monitoring of asthma.

Objectives: The aim of the study was to assess the correlation between FENO level and the values of spirometric parameters defining airflow obstruction.

Materials And Methods: The longitudinal study included a group of 89 children admitted to the Pediatric Clinic of "Grigore Alexandrescu" Emergency Clinical Hospital for Children. The inclusion criteria were: (i) a previously known diagnosis of asthma, (ii) age range between 5 and 18 years old. All patients underwent pulmonary function testing and measurement of FENO.

Results: Significant correlations were identified between FENO and a part of spirometric parameters: MEF75 (p=0.007), MEF50 (p=0.0.28), MEF25 (p=0.011) and PEF (p=0.020), but not with FEV1 (p=0.090), nor FVC (p=0.308). However, multiple linear regression analysis revealed that spirometric parameters poorly predict FENO variation (R=0.062, p=0.82). In adition, binary logistic regression analysis (LR) showed that FENO can not be used as a reliable biomarker (p=0.169) for the estimation of the risk for obstructive dysfunction.

Conclusion: The level of exhaled nitric oxide does not correlate with the values of spirometric values. More studies with a large number of patients are needed for establishing the role of FENO in the evaluation of airflow obstruction.