A comparison of exhaled nitric oxide measurements performed using three different analysers.

Abstract

INTRODUCTION:

Exhaled nitric oxide (NO) is an established technique for monitoring airway inflammation. We have compared exhaled NO measurements from 3 different analysers; Ecomedics (E), Niox (N) and Logan (L).

METHODS:

Thirty subjects (10 non-smoking healthy subjects, 10 non-smoking patients with asthma and 10 ex-smoking COPD patients) performed 3 repeated measurements of exhaled NO at a flow rate of 50 ml/s on each of the 3 analysers. Within analyser variability was determined by calculating the repeatability coefficient for each analyser. Differences between analysers were assessed by (1) the differences between group means and (2) the Bland Altman method to estimate the variability expected for an individual using the 3 analysers.

RESULTS:

The repeatability coefficients (expressed as ratios) were 1.12, 1.19 and 1.19 for N, E and L, respectively. There were significant differences (P<0.05) between analysers; the Logan analyser gave the highest group mean values and Ecomedics gave the lowest group mean values. Differences between analysers were observed in all subject groups (healthy, asthma, COPD). Similar results were obtained in the 3 groups when analysed separately. Bland Altman analysis gave the following ratios [data are mean ratio (95% limits of agreement)]; N:E 1.59 (1.02-2.50), L:N 1.23 (0.72-2.13), L:E 1.96 (1.09-3.57).

CONCLUSION:

Our findings indicate that exhaled NO measurements in healthy subjects and patients with airways disease differ according to the type of analyser used.

• Authors: Zoë Borrill, David Clough, Nick Truman, Julie Morris, Stephen Langley, Dave Singh
• Journal: Respiratory medicine (Respir Med) Vol. 100 Issue 8 Pg. 1392-6 (Aug 2006) ISSN: 0954-6111 [Print] England
• PMID: 16431095 (Publication Type: Comparative Study, Journal Article)

Chemical References

• Nitric Oxide

Topics

• Adult
• Aged
• Asthma (metabolism)
• Breath Tests (instrumentation)
• Exhalation
• Female
• Humans
• Male
• Nitric Oxide (analysis)
• Reproducibility of Results