Assessment of exhaled nitric oxide by a new hand-held device

Fractional exhaled nitric oxide (FENO) has been implicated as a pulmonary biomarker. The aim of this study was to compare the performance of a new hand-held device to a standard chemiluminescence analyzer and to another portable device.

FENO levels measured by NObreath (Bedfont) were compared to those of (1) a chemiluminescence detector (Logan, Logan Research) and (2) the electrochemical portable NIOX MINO (Aerocrine) in 18 healthy volunteers on three consecutive occasions: in the morning, 1 h and 24 h later.

Comparing FENO levels obtained by NObreath to those by Logan values were similar and a very close linear relationship was found between the two devices (r = 0.923, p < 0.001). The mean inter-device difference in FENO level was -3.45 ppb and the limits of agreement (Bland-Altman test) were -10.98 and 4.08 ppb. In the second series FENO levels obtained by NObreath were found to be slightly higher compared to those of NIOX MINO, but still showed a close correlation (r = 0.681, p < 0.001). The mean inter-device difference in FENO level was 4.36 ppb and the limits of agreement were -7.38 and 16.1 ppb. Analyzing the repeated FENO measurements, the mean coefficient of variation using NObreath tended to be lower than that of NIOX MINO (16.9 vs. 24.7%, p = 0.059), while it was similar as the value obtained with Logan (11.8 vs. 9.0%, p = 0.342).

FENO values measured with NObreath are reproducible and in good agreement with those obtained by NIOX MINO and Logan indicating that NObreath is suitable for use in clinical practice.