Dynamic Mechanical Interactions Between Neighboring Airspaces Determine Cyclic Opening and Closure in Injured Lung

Ludovic Broche (1, 2, 3, 4) , Gaetano Perchiazzi (5, 4) , Liisa Porra (6, 7) , Angela Tannoia (5) , Mariangela Pellegrini (5, 4) , Savino Derosa (5) , Alessandra Sindaco (5) , Joao Batista Borges (4, 8) , Loic Degrugilliers (3, 2) , Anders Larsson (4) , Goran Hedenstierna (4) , Anthony S. Wexler (9) , Alberto Bravin (1) , Sylvia Verbanck (10) , Bradford J. Smith (11) , Jason H. T. Bates (11) , Sam Bayat (3, 2)

1 ID17 - Biomedical Beamline
2 GRAMFC - Groupe de Recherche sur l'Analyse Multimodale de la Fonction Cérébrale - UMR INSERM_S 1105
3 CHU Amiens-Picardie
4 Uppsala University
5 UNIBA - Università degli studi di Bari Aldo Moro = University of Bari Aldo Moro
6 Helsingin yliopisto = Helsingfors universitet = University of Helsinki
7 HUS - Helsinki University Hospital [Finland]
8 USP - Universidade de São Paulo = University of São Paulo
9 UC Davis - University of California [Davis]
10 UZ Brussel - Universitair Ziekenhuis Brussel = University Hospital of Brussels
11 University of Vermont [Burlington]

Objectives: Positive pressure ventilation exposes the lung to mechanical stresses that can exacerbate injury. The exact mechanism of this pathologic process remains elusive. The goal of this study was to describe recruitment/derecruitment at acinar length scales over short-time frames and test the hypothesis that mechanical interdependence between neighboring lung units determines the spatial and temporal distributions of recruitment/derecruitment, using a computational model. Design: Experimental animal study. Setting: International synchrotron radiation laboratory. Subjects: Four anesthetized rabbits, ventilated in pressure controlled mode. Interventions: The lung was consecutively imaged at - 1.5-minute intervals using phase-contrast synchrotron imaging, at positive end expiratory pressures of 12, 9, 6, 3, and 0 cm H2O before and after lavage and mechanical ventilation induced injury. The extent and spatial distribution of recruitment/derecruitment was analyzed by subtracting subsequent images. In a realistic lung structure, we implemented a mechanistic model in which each unit has individual pressures and speeds of opening and closing. Derecruited and recruited lung fractions (F-derecruaed, F-recruited) were computed based on the comparison of the aerated volumes at successive time points. Measurements and Main Results: Alternative recruitment/derecruitment occurred in neighboring alveoli over short-time scales in all tested positive end-expiratory pressure levels and despite stable pressure controlled mode. The computational model reproduced this behavior only when parenchymal interdependence between neighboring acini was accounted for. Simulations closely mimicked the experimental magnitude of F-derecruited and F-recruited when mechanical interdependence was included, while its exclusion gave F-recruited values of zero at positive end -expiratory pressure greater than or equal to 3 cm H2O. Conclusions: These findings give further insight into the microscopic behavior of the injured lung and provide a means of testing protective-ventilation strategies to prevent recruitment/derecruitment and subsequent lung damage. (Crit Care Med 2017; 45:687-694)

Domaines: Sciences du Vivant [q-bio]

Ludovic Broche, Gaetano Perchiazzi, Liisa Porra, Angela Tannoia, Mariangela Pellegrini, et al.. Dynamic Mechanical Interactions Between Neighboring Airspaces Determine Cyclic Opening and Closure in Injured Lung. Critical Care Medicine, 2017, 45 (4), pp.687-694. ⟨10.1097/CCM.0000000000002234⟩. ⟨hal-03558225⟩