RT Journal Article
SR Electronic
T1 Respiratory mechanics in ventilated COPD patients: forced oscillation versus occlusion techniques
JF European Respiratory Journal
JO Eur Respir J
FD European Respiratory Society
SP 170
OP 176
DO 10.1183/09031936.98.12010170
VO 12
IS 1
A1 R Farre
A1 M Ferrer
A1 M Rotger
A1 A Torres
A1 D Navajas
YR 1998
UL http://erj.ersjournals.com/content/12/1/170.abstract
AB The respiratory mechanics of artificially ventilated chronic obstructive pulmonary disease (COPD) patients were investigated by means of the forced oscillation (FOT) and the end-inspiratory airway occlusion (AOT) techniques. FOT was applied to measure respiratory resistance (Rrs) and reactance (Xrs) from 0.25-16 Hz. Maximum (Rmax) and minimum (Rmin) resistances, static elastance (Est) and time constant (T) were computed by AOT. FOT and AOT data were interpreted with models featuring airway wall shunt, tissue viscoelasticity and parallel inhomogeneity. Rrs* and Xrs*, predicted from the AOT data, were computed and compared with Rrs and Xrs measured by FOT. Rrs and Xrs (hPa x s x L(-1)) decreased from 31.2+/-10.3 to 5.9+/-4.6 and increased from -20.3+/-7.1 to -8.0+/-4.4 from 0.25-16 Hz, respectively. Central resistance (Rc) and peripheral resistance (Rp) (in hPa x s x L(-1)), and shunt elastance (Esh) and tissue elastance (Et) (in hPa x L(-1)) were 4.4+/-5.4, 28.4+/-153, 723+/-393 and 31.8+/-10.1, respectively. Rmin, Rmax and Est were 18.4+/-5.9, 28.4+/-12.8 and 18.1+/-4.2 respectively, and T=0.76+/-0.25 s. The frequency dependence of predicted Rrs* and Xrs* differed markedly from that of measured Rrs and Xrs. The use of different models to interpret the measured data suggests that both airway and tissue properties determined the frequency dependence of respiratory resistance and respiratory reactance in ventilated chronic obstructive pulmonary disease patients at the investigated frequencies (0.25-16 Hz).