Repeatability of standardised nasal nitric oxide measurements in healthy and asthmatic adults and children.

UNLABELLED

Several nasal nitric oxide (NO) measurement techniques have been described, but there is not a widespread measurement technique for measurement of nasal NO. In this study we evaluated the repeatability of one technique of nasal NO measurements using the nasal application of the NIOX system.

METHODS

Three nasal NO measurements (NIOX Nitric Oxide Monitoring System, Aerocrine, Sweden) were made on a single occasion in 22 healthy subjects and 27 patients with asthma, aged 5-69 years. Nasal NO was sampled during breath hold from one nostril at a flow rate of 5 ml/s.

RESULTS

The repeatability of nasal NO assessed by the coefficient of variation (CV) was 12.5% (95% Confidence interval (CI) 11.0-14.7%) for the total population. Healthy adults had a significantly better repeatability than healthy children (P<0.008). The mean NO level for the total population was 837 ppb. The mean NO levels in children were lower than in the adults (751 and 897 ppb, respectively). The mean breath hold length needed to obtain a steady NO plateau for all subject categories combined was 20.4+/-6.01 s. The average number of attempts needed to obtain three approved NO measurements was 5.4 (range 3-13) for the total population. There were no significant differences between the different subject categories. When using two measurements per session instead of three, the overall CV was 10.5% (95% CI 8.8-13.1%). Most subjects found the measurements easy to perform and all of them would accept to do the examination as a routine.

CONCLUSIONS

Nasal NO measurements in NIOX may provide a useful reliable clinical tool to assess and monitor upper airways in different diseases, for example PCD and rhinitis, and are acceptable by both healthy and asthmatic adults and children, as a part of their routine visit to a physician.