A predictive and prognostic marker in COVID-19 patients: Exhaled Nitric Oxide (FENO)

Aydın Balci¹, Erkan Yıldız², Okan Selendili³, Ersin Günay⁴

¹Department of Chest Disease, Afyonkarahisar Healty Science University Hospital, Afyonkarahisar, Turkey - ²Department of Otolaryngology, Afyonkarahisar Şuhut State Hospital, Afyonkarahisar, Turkey - ³Department of Chest Disease, Manisa Alaşehir State Hospital, Manisa, Turkey ^{- 4} Department of Chest Disease, Medical Park Hospital, Ankara, Turkey

Introduction: It is known that nitric oxide (NO) is actively involved against microorganisms due to its antiviral and bacteriostatic activity in the upper respiratory tract and rises in the blood and exhaled air during this process. Therefore, considering that COVID-19 can damage various tissues and cells in the body, it is predicted that Covid-19 may be an early biomarker in the diagnosis of measurement of Nitric oxide (FENO) in Exhaled air. 

Materials and methods: 102 COVID-19 patients with different clinical findings, whose diagnoses were made by polymerase chain reaction (PCR) and whose treatment was started, were included in the study. A control group was formed from healthy volunteers. Demographic features, clinical findings and the amount of nitric oxide (FeNO) measured in exhaled air were recorded.

Results: In terms of exhaled nitric oxide (FeNO) values, the exhaled nitric oxide value in COVID-19 patients was 31.73 ± 14.80 mmol / lt, while it was 15.48 ± 6.64 mmol / lt in the control group and was statistically significant. In the Roc graph, FeNO threshold value was measured as 24.5 Mmol level and its sensitivity was 62.1% and specificity was 96.0% in diagnosing Covid-19.

Conclusion: Non-invasive method, FeNO measurement, can be used in an easy and outpatient environment and is reproducible. This shows that it is a candidate to be among the diagnostic methods in the future.