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Lung sound analysis correlates to injury and recruitment as identified by computed tomography: an experimental study
No full textOleic acid lung injury: a morphometric analysis using computed tomography
No full textBackground: The oleic acid-induced lung injury (OAI) model
is considered to represent the early phase of acute respiratory
distress syndrome (ARDS). Its inherent properties are important
for the design and the interpretation of interventional
studies. The aim of this study was to describe the evolution
of morphometric lung changes during OAI using computed
tomography (CT) analysis. Furthermore, the effect of a temporary
change in positive end-expiratory pressure (PEEP) was
evaluated.
Methods: Fifteen anaesthetized pigs were ventilated in
volume-controlled mode with a baseline PEEP of 5 cm H2O.
Helical CT scans were taken at baseline and 1 h after oleic acid
injection. The PEEP was then either increased to 10 cm H2O
(n1⁄45), decreased to 0 cm H2O (n1⁄45) or kept constant (n1⁄45)
for 30min. For the next 30min, the baseline PEEP level was
applied in all animals before the final CT scans 2 h after the
induction of OAI. Dimensional and volumetric changes were
determined from radiographical attenuation values.
Results: There was a major decrease in gas volume and an
increase in tissue volume within the first hour. A net increase
in total lung volume, with a larger transverse area but no
displacement of the diaphragm, was manifest after 2 h. A minor
increase in volume of non-aerated lung, located to the caudal
region, was observed during the second hour. The tidal volume
was redistributed to the middle and apical regions. The temporary
change in PEEP did not influence the morphological
progress of OAI.
Conclusion: Decreased gas volume and increased tissue
volume are the dominating morphometric characteristics of
oleic acid lung injury, occurring mainly within the first hour.
With these changes manifest, the course of injury is not affected
by a limited period of moderately changed PEEP during the
second hour. The net increase of total lung volume suggests a
predominance of oedema formation over airway and alveolar
collapse
Assessement of Respiratory Mechanics Using Neural Networks: is the Choice of Training Data Important?
No full textRespiratory System Mechanics in an Animal Acute Lung Injury (ALI) Model Assessed by Artificial Neural Networks
No full textMeccanica del Sistema Respiratorio in un Modello Animale di Acute Lung Injury: Uso di Reti Neurali
No full textFunctional residual capacity and respiratory mechanics as indicators of aeration and collapse in experimental lung injury
No full textIncreased functional residual capacity (FRC) and compliance
are two desirable, but seldom measured, effects of
positive end-expiratory pressure (PEEP) in mechanically
ventilated patients. To assess how these variables reflect
the morphological lung perturbations during the evolution
of acute lung injury and the morphological changes
from altered PEEP, we correlated measurements of FRC
and respiratory system mechanics to the degree of lung
aeration and consolidation on computed tomography
(CT).Weused a porcine oleic acid model with FRC determinationsbysulfur
hexafluoride washin-washoutandrespiratory
system mechanics measured during an inspiratory
hold maneuver. Within the first hour, during
constant volume-controlled ventilation with PEEP 5 cm
H2O, FRC decreased by 45%15% (P0.005) and compliance
decreased by 35% 12% (P 0.005). Resistance
increased by 60% 62% (P 0.005). Only the FRC
changes correlated significantly to the decreased aeration
(R20.56;P0.01)andthe increased consolidation (R2
0.43; P 0.04) on CT. When the PEEP was changed to
either 10 or 0 cm H2O, there were larger changes in FRC
than in compliance. We conclude that, in our model, FRC
was a more sensitive indicator of PEEP-induced aeration
and recruitment of lung tissue and thatFRCmaybe a useful
adjunct to Pao2 monitoring
Lung tissue volumes of different attenuation on computed tomography in experimental injury
No full textFunctional residual capacity and radiographic lung volumes in a porcine lung injury model
No full textRespiratory System Mechanics during Acute Lung Injury: Use of Artificial Neural Networks in an Animal Model
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