Niox mino

nNO and FENO levels were measured using an online electrochemical analyzer equipped with nNO software (NIOX MINO; Aerocrine AB, Sweden) in compliance with the American Thoracic Society/European Respiratory Society recommendations.¹⁸ (link) Briefly, nNO levels were measured from the nostril while holding the breath with an aspiration flow of 5 ​mL/s. The NO levels derived from the nose were recorded by introducing a nasal olive connected to the analyzer into one nostril. The nNO concentration was automatically calculated by the NIOX MINO system. The nasal olive was then placed in the other nostril and the test was repeated. Measurements were made in triplicate for both nostrils and the mean nNO level was used for the analysis. The subjects rested for 15 ​min after nNO measurement before undergoing the FENO examination. FENO measurements were made according to standard guidelines.⁵ (link) All children avoided physical exercise and consumption of foods rich in nitrogen such as sausages, various animal offal, lettuce, and spinach within two hours of nNO measurement. Finally, all enrolled children satisfied all the requirements and successfully completed the nNO and FENO measurements.

FeNO was measured by an NO analyzer with electrochemical sensors (NIOX MINO, Aerocrine AB, Solna, Sweden), according to American Thoracic Society (ATS)/European Respiratory Society (ERS) guidelines16) (link), and expressed as parts per billion (ppb). The children were instructed to avoid eating, drinking, and strenuous exercise 2 hours before FeNO measurements. After inhalation of ambient air through a nitric oxide scrubber to total lung capacity, subjects then exhaled against expiratory resistance to exclude nasal air. Exhalation times were 10 seconds with a 2-minute analysis period. Repeated exhalations (2 values that agreed within 5% or 3 that agreed within 10%) were performed without a nose clip at a constant flow rate of 50 mL/sec.

Fractional exhaled nitric oxide (FeNO) levels were measured using a nitric oxide monitor (NIOX MINO^®, Aerocrine, Solna, Sweden) according to the 2005 American Thoracic Society/European Respiratory Society guidelines.15 (link) The subjects were asked about current medications or food intake that could interfere with the FeNO measurement results, and were instructed to avoid smoking, exercise, and ingestion of food, water, or caffeine for at least 1 hour before testing.
While seated, the subjects exhaled fully, inhaled for 2–3 seconds to total lung capacity through an NIOX filter, and then exhaled with an upper airway pressure of 5–20 cm H₂O. FeNO measurements were taken from a 3-second stable plateau of the exhaled NO concentration. The lowest detection limit of the NIOX MINO^® is 5 parts per billion (ppb), and values <5 ppb were regarded as 2.5 ppb. The average values of at least 2 acceptable measurements were used.