The clinical usefulness of a new hand-held device for fractional exhaled nitric oxide measurement, NIOX VERO®, for diagnosing the etiology of cough

Cough is one of the most common symptoms seen in clinical practice, however the differential diagnosis is often difficult. The utility of fractional exhaled nitric oxide (FeNO) measurement in the differential diagnosis of the etiology of cough has been reported. NIOX VERO® (NOV) is a new hand-held device that will replace NIOX MINO®, but its diagnostic utility has not been fully elucidated in clinical practice. In this study, the performance of NOV for FeNO measurements was determined. We retrospectively analyzed 243 consecutive patients complaining cough. Among 243 patients, final diagnosis was cough variant asthma (CVA) in 74 (30.5%), bronchial asthma (BA) in 48 (19.8%), post-infectious cough (PIC) in 52 (21.4%), atopic chough (AC) in 24 (9.9%), gastroesophageal reflux disease (GERD) in 10 (4.1%), and Others in 35 (14.4%). FeNO values were significantly higher in CVA and BA as compared to PIC, AC, GERD, and Others. In the multivariate analysis, only FeNO value was identified as independent factors to discriminate CVA and non-CVA other than BA. These findings indicated that FeNO measured by using NOV could be used as a diagnostic marker of intractable cough, especially for the differential diagnosis of CVA from non-CVA. J. Med. Invest. 67 : 265-270, August, 2020.

Comparison of fractional exhaled nitric oxide levels measured by different analyzers produced by different manufacturers

Objective: Fractional exhaled nitric oxide (FeNO) is widely used as a biomarker of allergic airway inflammation. At present, both stationary chemiluminescence and portable electrochemical analyzers produced by different manufacturers are available. However, it remains debatable whether those analyzers are comparable to each other. We compare FeNO levels obtained by different analyzers.Methods: For the first study, 153 subjects were enrolled to compare differences in FeNO levels measured using three analyzers (NA623NP^®, NObreath^®, and NIOX MINO^®) which were produced by different manufacturers. For the second study, 30 subjects were recruited to compare FeNO levels obtained by the two analyzers (NIOX MINO^® and NIOX VERO^®) produced by the same manufacturer. FeNO was measured twice using each analyzer in random order.Results: FeNO levels obtained using the NIOX MINO^® and NObreath^® were more variable than those measured using the NA623NP^®. There were strong positive correlations in FeNO levels measured by the NA623NP^®, NIOX MINO^®, and NObreath^® (p < 0.001). The NA623NP^® and NIOX MINO^® provided the highest and lowest FeNO levels, respectively; whereas, those obtained by NObreath^® were intermediate. No significant differences were observed in FeNO levels obtained using the NIOX MINO^® and NIOX VERO^®.Conclusions: FeNO levels measured by the NIOX MINO^® and NIOX VERO^®, both of which were produced by the same manufacturer, have comparability. However, significant differences in FeNO levels exist when measured by analyzers manufactured by different manufacturers. This should be taken into account for FeNO measurement.