Open AccessFunctional respiratory imaging, regional strain, and expiratory time constants at three levels of positive end expiratory pressure in an ex vivo pig model
Author(s) -
Henderson William R.,
MolgatSeon Yannick,
Vos Wim,
Lipson Rachel,
Ferreira Francisca,
Kirby Miranda,
Holsbeke Cedric Van,
Dominelli Paolo B.,
Griesdale Donald E. G.,
Sekhon Mypinder,
Coxson Harvey O.,
Mayo John,
William Sheel A.
Publication year - 2016
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.13059
Subject(s) - spirometry , respiratory system , lung , respiratory physiology , lung volumes , medicine , positive end expiratory pressure , in vivo , ex vivo , cardiology , nuclear medicine , biology , asthma , microbiology and biotechnology
Heterogeneity in regional end expiratory lung volume ( EELV ) may lead to variations in regional strain ( ε ). High ε levels have been associated with ventilator‐associated lung injury ( VALI ). While both whole lung and regional EELV may be affected by changes in positive end‐expiratory pressure ( PEEP ), regional variations are not revealed by conventional respiratory system measurements. Differential rates of deflation of adjacent lung units due to regional variation in expiratory time constants ( τ E ) may create localized regions of ε that are significantly greater than implied by whole lung measures. We used functional respiratory imaging ( FRI ) in an ex vivo porcine lung model to: (i) demonstrate that computed tomography ( CT )‐based imaging studies can be used to assess global and regional values of ε and τ E and, (ii) demonstrate that the manipulation of PEEP will cause measurable changes in total and regional ε and τ E values. Our study provides three insights into lung mechanics. First, image‐based measurements reveal egional variation that cannot be detected by traditional methods such as spirometry. Second, the manipulation of PEEP causes global and regional changes in R, E, ε and τ E values. Finally, regional ε and τ E were correlated in several lobes, suggesting the possibility that regional τ E could be used as a surrogate marker for regional ε .