RT Journal Article
SR Electronic
T1 Within-breath changes of respiratory impedance in COPD and healthy adults
JF European Respiratory Journal
JO Eur Respir J
FD European Respiratory Society
SP 3487
VO 42
IS Suppl 57
A1 András Lorx
A1 Dóra Bartusek
A1 Szabolcs Szigeti
A1 Réka Stein-Udvardi
A1 Ádám Bálint
A1 János Gál
A1 György Losonczy
A1 Peter Sly
A1 Zoltán Hantos
YR 2013
UL http://erj.ersjournals.com/content/42/Suppl_57/3487.abstract
AB Reduction of respiratory system reactance (Xrs) in expiration indicates expiratory flow limitation in COPD patients (Dellacà et al., Eur Respir J, 23: 232, 2004). The aim of our study was to determine within-breath changes in respiratory resistance (Rrs) and Xrs, as functions of tidal flow (V’) and volume (V).Forced oscillations at 8 Hz were superimposed on quiet breathing in 44 COPD (GOLD III and IV) patients and 13 control subjects (C), and Rrs and Xrs estimated every 1/8 s. Values of Rrs and Xrs were compared at their extremes (min and max), values at minimum (vmin) and maximum volume (vmax), maximum inspiratory (ifmax) and expiratory flow (efmax), and the area of the Xrs vs V loop normalized for V (AXrs).Strong dependence of Rrs and Xrs on V’ and V were observed in all subjects but with markedly different loop patterns in the two groups.The differences between COPD and C were highly significant in the group median values of AXrs (4.2 vs 0.5 hPa.s/l), Xrs(min) (-9.8 vs -2.1 hPa.s/l), Xrs(vmin) (-4.7 vs -0.5 hPa.s/l), and Xrs(efmax) (-4.8 vs -0.4 hPa.s/l), Rrs(ifmax) (5.1 vs 3.9 hPa.s/l), all P<0.01, but not in eRrs(fmax) (5.20 vs 5.17 hPa.s/l).Tracking of oscillatory impedance can be accomplished easily with minimum demand for cooperation and no complex respiratory manoeuvres, and reveals characteristic within-breath changes in airway size and rheology. The development of flow limitation is seen in COPD.