RT Journal Article SR Electronic T1 Passive partitioning of respiratory volumes and time constants in ventilated patients JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP 1009 OP 1017 DO 10.1183/09031936.93.05081009 VO 5 IS 8 A1 J Dall'Ava-Santucci A1 F Brunet A1 S Nouira A1 A Armaganidis A1 JF Dhainaut A1 JF Monsallier A1 A Lockhart YR 1992 UL http://erj.ersjournals.com/content/5/8/1009.abstract AB If the thoracoabdominal partitioning of volumes in the mechanical respiratory apparatus was constant, one transducer of indirect spirometry should be sufficient to measure volume variations. To verify this hypothesis we used respiratory inductive plethysmography (RIP) in 16 paralysed patients, of whom eight had normal lungs and 8 had not, to measure: 1) the thoracoabdominal partitioning of volumes (400-1,200 ml) insufflated from either a syringe (Syr) or a ventilator (Vent); and 2) thoracic (Tho) and abdominal (Abd) time constants (T0.368) on spontaneous deflation to barometric pressure. In eleven additional subjects with normal lungs we measured only the time constants. 1) Correlation coefficients of the calibration lines were in all but one subject > 0.98. In all patients the error of volume was < +/- 10% when either one of two coils alone was used to assess volumes with no difference between the two coils; 2) Partitioning varied little with volumes (4 +/- 2%), but widely between subjects, with no group average significant difference between Syr and Vent; 3) T0.368 were identical for Tho and Abd except in one patient; 4) Partitioning and T0.368 were volume size independent. We conclude that, to measure volume variations and time constants in ventilated, paralysed patients, the use of either a thoracic or abdominal single coil RIP is justified. We also provide the normal range for time constant in 19 subjects (0.73 +/- 0.29 s).