Airway inflammation in moderate/severe asthma and concomitant OSA patients- FeNO assessment

Abstract

Fractional Exhaled Nitric Oxide (FeNO) is a biomarker for allergic and\or eosinophilic airway inflammation assessment in asthmatics. Obstructive Sleep Apnea (OSA) increases upper airway inflammation by pharynx increased vibration and collapse. This report analyzed whether FeNO assessed airway inflammation was further increased in moderate/severe asthmatic patients with concomitant Obstructive Sleep Apnea (cOSA) versus moderate/severe asthma alone patients, and if OSA Positive Airway Pressure (PAP) treatment could impact the FeNO scores. OSA diagnosis was considered if apnea/hypopnea index ≥5 events\h. PAP was initiated in patients with symptomatic OSA. PAP adherence was considered if > 70% days of use and > 4h/night. 66 asthmatic patients, GINA step 4 or 5, were included. 24 presented with asthma alone, 42 with asthma and cOSA, of which 16 not treated with PAP. cOSA patients had higher FeNO (>25ppb) compared to asthma alone, but not with statistical significance (p=0,356). FeNO was significantly higher in cOSA patients non adherent/not treated with PAP (p<0,05) versus cOSA adherent to PAP and versus asthma only. Mild cOSA had significantly higher (p<0,05) FeNO values, when compared to moderate\severe cOSA subjects. The mean FeNO scores were lower in both PAP treated groups, being that reduction of significance (p<0,05) in the moderate-severe cOSA patients. These findings seem to support a cumulative effect in the airway inflammation due to non-treated cOSA in moderate/severe asthmatic patients. PAP treatment seems to reduce airway inflammation burden, even in mild cOSA patients. Further investigation is needed to clarify the importance of lowering airway inflammation in these patients.