PT  - JOURNAL ARTICLE
AU  - Joanna Lyons
AU  - Claude Farah
AU  - Leigh Seccombe
AU  - Gregory King
AU  - Cindy Thamrin
TI  - The effect of duration and number of measurements on respiratory resistance and reactance in airways disease
AID  - 10.1183/13993003.congress-2015.PA2281
DP  - 2015 Sep 01
TA  - European Respiratory Journal
PG  - PA2281
VI  - 46
IP  - suppl 59
4099  - http://erj.ersjournals.com/content/46/suppl_59/PA2281.short
4100  - http://erj.ersjournals.com/content/46/suppl_59/PA2281.full
SO  - Eur Respir J2015 Sep 01; 46
AB  - Introduction: The forced oscillation technique (FOT) is established in research settings. Commercial device availablility facilitates its adoption for clinical use. Guidelines recommend 3-5 technically acceptable measurements, however the optimum number or duration of FOT measurements has not been systematically determined, especially in asthma and COPD.Aim: To compare the effect of different duration and number of measurements on FOT results in asthma and COPD.Methods: 21 subjects (8 male) with asthma or COPD breathed tidally on a tremoFlo C-100 (Thorasys Medical Systems, Canada) FOT device for 60 s, repeated 3 times. Within-breath analysis was performed on the first 16, 30 and 60 s of each measurement to obtain total, inspiratory and expiratory Rrs and Xrs at 5 Hz. The effects of duration and of averaging the first 1, 2 and 3 measurements were examined separately using one-way repeated measures ANOVA.Results: There were no significant differences between 16, 30 or 60-s measurements (n=54 measurements) . There were also no significant differences between taking the first 1, 2 or 3 measurements, for any measurement duration (n=15 subjects).View this table:Table 1Conclusions: FOT results are not affected by duration or number of measurements. The decision for optimum settings should take into account variability, breathing rate and practical considerations.