PT  - JOURNAL ARTICLE
AU  - Francisca Ferreira
AU  - W.R. Henderson
AU  - Cedric Van Holsbeke
AU  - Wim Vos
AU  - Jan De Backer
AU  - Yannick Molgat-Seon
AU  - Miranda Kirby
AU  - Paolo Dominelli
AU  - Donald Griesdale
AU  - MyPinder Sekhon
AU  - Harvey Coxson
AU  - John Mayo
AU  - William Sheel
TI  - Measurements of regional strain and time constants in ex-vivo animal models at different PEEP levels using functional respiratory imaging (FRI)
AID  - 10.1183/13993003.congress-2015.OA4475
DP  - 2015 Sep 01
TA  - European Respiratory Journal
PG  - OA4475
VI  - 46
IP  - suppl 59
4099  - http://erj.ersjournals.com/content/46/suppl_59/OA4475.short
4100  - http://erj.ersjournals.com/content/46/suppl_59/OA4475.full
SO  - Eur Respir J2015 Sep 01; 46
AB  - Aims and objectives: In ARDS, lung units are characterized by large heterogeneities of distension and variations in resistance and compliance. Regional heterogeneity in time constant (τ) values may have meaningful consequences in injured lung during ventilation by creating regional differences of strain (ε), or zones of high shear stress and shear strain between lung regions. In this study, we hypothesized that FRI can be used to assess regional values of ε and inspiratory τ (τI) and the influence of positive end expiratory pressure (PEEP) on these parameters.Methods: Ex-vivo lungs of five adult female Yorkshire pigs were ventilated with a PEEP of 0, 5 and 10cmH2O during CT scans. Three-dimensional reconstructions of the airways (see figure 1), the right and left anterior lobes (RAL and LAL), right and left caudal lobes (RCL and LCL), right and left diaphragmatic lobes (RDL and LDL) and right internal lobe (RIL) at full inspiration and expiration were created. Using FRI, lobar ε and τI values were calculated at the different PEEP levels.Results: Strain decreased linearly with increasing PEEP (p=0.001). RAL was found to have the lowest ε while no differences were observed between the other lobes. The τI decreased quadratically in a concave pattern with increasing PEEP (p<0.001). LCL, RAL and RIL had smaller τI than the other lobes.Conclusions: FRI can be used to assess global and regional values of ε and τI. The manipulation of PEEP causes changes in regional ε that are reflected by changes in τI values.