Chinese Expert Consensus on the Testing Process, Quality Control and Clinical Application of Fractional Exhaled Nitric Oxide (2025).

Fractional exhaled nitric oxide (FeNO) is an internationally recognized biomarker for type 2 airway inflammation. With the increasing promotion and widespread use of FeNO testing in China, Chinese experts have previously published consensus regarding FeNO measurement principles and clinical applications for adults and children respectively. However, in clinical practice, due to insufficient understanding of the detection principles, quality control requirements, and standardized operational procedures, questions have been raised on FeNO measurement's accuracy and clinical significance, which indeed limit the widespread application of FeNO in clinical settings. Based on the achievements in this area worldwide, this consensus elaborated the details and development on the principle of FeNO instruments, FeNO detection method, operation process, quality control, clinical significance, etc. Hopefully, this consensus document can be used to promote standardized FeNO testing protocols and better serve the precise diagnosis and treatment of airway diseases.