title: Airway dynamics in COPD patients by within-breath impedance tracking: effects of continuous positive airway pressure.
abstract: Tracking of the within-breath changes of respiratory mechanics using the forced oscillation technique may provide outcomes that characterise the dynamic behaviour of the airways during normal breathing.We measured respiratory resistance (Rrs) and reactance (Xrs) at 8 Hz in 55 chronic obstructive pulmonary disease (COPD) patients and 20 healthy controls, and evaluatedRrsandXrsas functions of gas flow (V') and volume (V) during normal breathing cycles. In 12 COPD patients, additional measurements were made at continuous positive airway pressure (CPAP) levels of 4, 8, 14 and 20 hPa.TheRrsandXrsversus V' andVrelationships displayed a variety of loop patterns, allowing characterisation of physiological and pathological processes. The main outcomes emerging from the within-breath analysis were theXrsversus Vloop area (AXV) quantifying expiratory flow limitation, and the tidal change inXrsduring inspiration (ΔXI) reflecting alteration in lung inhomogeneity in COPD. With increasing CPAP, AXV and ΔXIapproached the normal ranges, although with a large variability between individuals, whereas meanRrsremained unchanged.Within-breath tracking ofRrsandXrsallows an improved assessment of expiratory flow limitation and functional inhomogeneity in COPD; thereby it may help identify the physiological phenotypes of COPD and determine the optimal level of respiratory support.
authors.affiliation: Dept of Anaesthesiology and Intensive Therapy, Semmelweis University, Budapest, Hungary.|Dept of Pulmonology, Semmelweis University, Budapest, Hungary.
authors.forename: András
authors.initials: A
authors.lastname: Lorx
authors.affiliation: Child Health Research Centre, University of Queensland, Brisbane, Australia.
authors.forename: Dorottya
authors.initials: D
authors.lastname: Czövek
authors.affiliation: Dept of Technical Informatics, University of Szeged, Szeged, Hungary.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Gingl
authors.affiliation: Dept of Technical Informatics, University of Szeged, Szeged, Hungary.
authors.forename: Gergely
authors.initials: G
authors.lastname: Makan
authors.affiliation: Dept of Pulmonology, University of Szeged, Szeged, Hungary.
authors.forename: Bence
authors.initials: B
authors.lastname: Radics
authors.affiliation: Dept of Pulmonology, Semmelweis University, Budapest, Hungary.
authors.forename: Dóra
authors.initials: D
authors.lastname: Bartusek
authors.affiliation: Dept of Pulmonology, Semmelweis University, Budapest, Hungary.
authors.forename: Szabolcs
authors.initials: S
authors.lastname: Szigeti
authors.affiliation: Dept of Anaesthesiology and Intensive Therapy, Semmelweis University, Budapest, Hungary.
authors.forename: János
authors.initials: J
authors.lastname: Gál
authors.affiliation: Dept of Pulmonology, Semmelweis University, Budapest, Hungary.
authors.forename: György
authors.initials: G
authors.lastname: Losonczy
authors.affiliation: Child Health Research Centre, University of Queensland, Brisbane, Australia.
authors.forename: Peter D
authors.initials: PD
authors.lastname: Sly
authors.affiliation: Dept of Pulmonology, University of Szeged, Szeged, Hungary hantos.zoltan@med.u-szeged.hu.|Dept of Medical Physics and Informatics, University of Szeged, Szeged, Hungary.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Hantos
mesh_terms: D000368:Aged; D000403:Airway Resistance; D016022:Case-Control Studies; D045422:Continuous Positive Airway Pressure; D017097:Electric Impedance; D045853:Exhalation; D005260:Female; D006801:Humans; D006814:Hungary; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology* / Q000628:therapy*; D012119:Respiration; D012129:Respiratory Function Tests / Q000379:methods