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Synchrotron Imaging Shows Effect of Ventilator Settings on Intrabreath Cyclic Changes in Pulmonary Blood Volume

Porra, Liisa
Broche, Ludovic
Dégrugilliers, Loïc
Malaspinas, Iliona
Wallin, Mats
Hallbäck, Magnus
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Published in American Journal of Respiratory Cell and Molecular Biology. 2017, vol. 57, no. 4, p. 459-467
Abstract Despite the importance of dynamic changes in the regional distributions of gas and blood during the breathing cycle for lung function in the mechanically ventilated patient, no quantitative data on such cyclic changes are currently available. We used a novel gated synchrotron computed tomography imaging to quantitatively image regional lung gas volume (Vg), tissue density, and blood volume (Vb) in six anesthetized, paralyzed, and mechanically ventilated rabbits with normal lungs. Images were repeatedly collected during ventilation and steady-state inhalation of 50% xenon, or iodine infusion. Data were acquired in a dependent and nondependent image level, at zero end-expiratory pressure (ZEEP) and 9 cm H2O (positive end-expiratory pressure), and a tidal volume (Vt) of 6 ml/kg (Vt1) or 9 ml/kg (Vt2) at an Inspiratory:Expiratory ratio of 0.5 or 1.7 by applying an end-inspiratory pause. A video showing dynamic decreases in Vb during inspiration is presented. Vb decreased with positive end-expiratory pressure (P = 0.006; P = 0.036 versus Vt1-ZEEP and Vt2-ZEEP, respectively), and showed larger oscillations at the dependent image level, whereas a 45% increase in Vt did not have a significant effect. End-inspiratory Vb minima were reduced by an end-inspiratory pause (P = 0.042, P = 0.006 at nondependent and dependent levels, respectively). Normalized regional Vg:Vb ratio increased upon inspiration. Our data demonstrate, for the first time, within-tidal cyclic variations in regional pulmonary Vb. The quantitative matching of regional Vg and Vb improved upon inspiration under ZEEP. Further study is underway to determine whether these phenomena affect intratidal gas exchange.
Keywords AnimalsBlood VolumeFemaleImage InterpretationComputer-AssistedInhalationLung/blood supply/diagnostic imaging/physiopathologyMaleRabbitsRespirationArtificialSynchrotronsVentilatorsMechanical
PMID: 28535074
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Research group Enfants et hyperréactivité bronchique (69)
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PORRA, Liisa et al. Synchrotron Imaging Shows Effect of Ventilator Settings on Intrabreath Cyclic Changes in Pulmonary Blood Volume. In: American Journal of Respiratory Cell and Molecular Biology, 2017, vol. 57, n° 4, p. 459-467. doi: 10.1165/rcmb.2017-0007OC https://archive-ouverte.unige.ch/unige:111092

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Deposited on : 2018-11-21

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