title: Measurement duration impacts variability but not impedance measured by the forced oscillation technique in healthy, asthma and COPD subjects.
abstract: The forced oscillation technique (FOT) is gaining clinical acceptance, facilitated by more commercial devices and clinical data. However, the effects of variations in testing protocols used in FOT data acquisition are unknown. We describe the effect of duration of data acquisition on FOT results in subjects with asthma, chronic obstructive pulmonary disease (COPD) and healthy controls. FOT data were acquired from 20 healthy, 22 asthmatic and 18 COPD subjects for 60 s in triplicate. The first 16, 30 and 60 s of each measurement were analysed to obtain total, inspiratory and expiratory resistance of respiratory system (Rrs) and respiratory system reactance (Xrs) at 5 and 19 Hz. With increasing duration, there was a decrease in total and expiratoryRrsfor healthy controls, total and inspiratoryRrsfor asthmatic subjects and magnitude of total and inspiratoryXrsfor COPD subjects at 5 Hz. These decreases were small compared to the differences between clinical groups. Measuring for 16, 30 and 60 s provided ≥3 acceptable breaths in at least 90, 95 and 100% of subjects, respectively. The coefficient of variation for totalRrsandXrsalso decreased with duration. Similar results were found forRrsandXrsat 19 Hz. FOT results are statistically, but likely minimally, impacted by acquisition duration in healthy, asthmatic or COPD subjects.
authors.affiliation: The Woolcock Institute of Medical Research, University of Sydney, Glebe, NSW, Australia.
authors.forename: Joanna C
authors.initials: JC
authors.lastname: Watts
authors.affiliation: The Woolcock Institute of Medical Research, University of Sydney, Glebe, NSW, Australia; Dept of Respiratory Medicine, Concord Repatriation General Hospital, Concord, NSW, Australia.
authors.forename: Claude S
authors.initials: CS
authors.lastname: Farah
authors.affiliation: Dept of Respiratory Medicine, Concord Repatriation General Hospital, Concord, NSW, Australia.
authors.forename: Leigh M
authors.initials: LM
authors.lastname: Seccombe
authors.affiliation: Dept of Respiratory Medicine, Royal North Shore Hospital, St Leonards, NSW, Australia.
authors.forename: Blake M
authors.initials: BM
authors.lastname: Handley
authors.affiliation: Dept of Respiratory Medicine, Royal North Shore Hospital, St Leonards, NSW, Australia.
authors.forename: Robin E
authors.initials: RE
authors.lastname: Schoeffel
authors.affiliation: The Woolcock Institute of Medical Research, University of Sydney, Glebe, NSW, Australia.
authors.forename: Amy
authors.initials: A
authors.lastname: Bertolin
authors.affiliation: The Woolcock Institute of Medical Research, University of Sydney, Glebe, NSW, Australia.
authors.forename: Jessica
authors.initials: J
authors.lastname: Dame Carroll
authors.affiliation: The Woolcock Institute of Medical Research, University of Sydney, Glebe, NSW, Australia; Dept of Respiratory Medicine, Royal North Shore Hospital, St Leonards, NSW, Australia.
authors.forename: Gregory G
authors.initials: GG
authors.lastname: King
authors.affiliation: The Woolcock Institute of Medical Research, University of Sydney, Glebe, NSW, Australia.
authors.forename: Cindy
authors.initials: C
authors.lastname: Thamrin