PT  - JOURNAL ARTICLE
AU  - V Antonaglia
AU  - A Grop
AU  - P Demanins
AU  - F Beltrame
AU  - U Lucangelo
AU  - A Peratoner
AU  - L De Simoni
AU  - A Gullo
AU  - J Milic-Emili
TI  - Single-breath method for assessing the viscoelastic properties of the respiratory system
AID  - 10.1183/09031936.98.12051191
DP  - 1998 Nov 01
TA  - European Respiratory Journal
PG  - 1191--1196
VI  - 12
IP  - 5
4099  - http://erj.ersjournals.com/content/12/5/1191.short
4100  - http://erj.ersjournals.com/content/12/5/1191.full
SO  - Eur Respir J1998 Nov 01; 12
AB  - In order to explain the time dependency of resistance and elastance of the respiratory system, a linear viscoelastic model (Maxwell body) has been proposed. In this model the maximal viscoelastic pressure (Pvisc.max) developed within the tissues of the lung and chest wall at the end of a constant-flow (V') inflation of a given time (tI) is given by: Pvisc,max = R2V'(1-e(-tI/tau2), where R2 and tau2 are, respectively, the resistance and time constant of the Maxwell body. After rapid airway occlusion at t1, tracheal pressure (Ptr) decays according to the following function: Ptr(t) = Pvisc(t) + Prs,st = Pvisc,max(etocc/tau2)+ Prs,st, where tocc/is time after occlusion and Prs,st is static re-coil pressure of the respiratory system. By fitting Ptr after occlusion to this equation, tau2 and Pvisc,max are obtained. Using these values, together with the V' and tI pertaining to the constant-flow inflation preceding the occlusion, R2 can be calculated from the former equation. Thus, from a single breath, the constants tau2, R2 and E2 (R2/tau2) can be obtained. This method was used in 10 normal anaesthetized, paralysed, mechanically ventilated subjects and six patients with acute lung injury. The results were reproducible in repeated tests and similar to those obtained from the same subjects and patients with the time-consuming isoflow, multiple-breath method described previously.