NO (nitric oxide) is produced in the epithelial cells of the bronchial wall and its production increases as part of the eosinophilic inflammatory process. As such, NO levels correlate with the degree of inflammation present in the airways, even in the absence of obvious clinical symptoms.

Normal epithelial cells release a minimum amount of NO.		Activated epithelial cells during inflammation demonstrate increased production of NO.

The clinical value of measuring NO has been confirmed in over 1500 peer-reviewed publications over the past 15 years.

Aerocrine have worked closely with the American Thoracic Society (ATS) and the European Respiratory Society (ERS) to develop guidelines for performing exhaled NO measurements. 

These guidelines state that FENO, expressed in parts per billion (ppb), must be performed at a controlled and standardized exhalation flow rate of 50ml/sec as FENO levels are highly flow dependent. The ATS/ERS guidelines also recommend that, the patient inhales NO-free air prior to testing, and specify the correct exhalation time and how the NO content should be analysed.

Unlike other NO monitoring devices, NIOX Flex and NIOX MINO, designed and manufactured by Aerocrine, meet all the requirements of the ATS/ERS guidelines. Specifically, the NIOX Flex and NIOX MINO are the only currently available devices that include a NO scrubbing device to ensure that the patient inhales NO-free air before testing.