TY - JOUR T1 - A single-compartment model cannot describe passive expiration in intubated, paralysed humans JF - European Respiratory Journal JO - Eur Respir J SP - 458 LP - 464 DO - 10.1183/09031936.93.04040458 VL - 4 IS - 4 AU - GL Chelucci AU - F Brunet AU - J Dall'Ava-Santucci AU - JF Dhainaut AU - D Paccaly AU - A Armaganidis AU - J Milic-Emili AU - A Lockhart Y1 - 1991/04/01 UR - http://erj.ersjournals.com/content/4/4/458.abstract N2 - The time-course of thoracic volume changes (respiratory inductive plethysmograph) during relaxed expiration was studied in 11 intubated, paralysed, mechanically ventilated subjects. The semilog volume-time curves show that expiration is governed by two apparently separate mechanisms: one causes emptying of most of the expired volume (approximately 80%) with a time constant of 0.50 +/- 0.22 s for a baseline tidal volume of 0.44 +/- 0.12 l (mean +/- SD) and 0.37 +/- 0.14 s when the tidal volume is reduced (VTP); the other contributes a relatively small amount to the expired volume over a significantly longer time, the time constant amounting to 3.27 +/- 1.54 s for baseline VT and 2.95 +/- 1.65 s for VTp. The first mechanism probably reflects the standard elastic and flow resistive properties of the respiratory system, while the second, slower compartment, is probably an expression of the viscoelastic properties of the pulmonary and chest wall tissues. ER -