1. Effects of Positive End-Expiratory Pressure and Spontaneous Breathing Activity on Regional Lung Inflammation in Experimental Acute Respiratory Distress Syndrome
- Author
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Luigi Vivona, Martin Scharffenberg, Robert Huhle, Axel Denz, Thomas Bluth, Paolo Pelosi, Alice Bergamaschi, Thea Koch, Jakob Wittenstein, Johannes Herold, Anja Braune, Marco Millone, Marcos F. Vidal Melo, Patricia R. M. Rocco, Moritz Herzog, Marcelo Gama de Abreu, Thomas Kiss, Jörg Kotzerke, and Michael Andreeff
- Subjects
Male ,medicine.medical_specialty ,Swine ,medicine.medical_treatment ,Lung injury ,Critical Care and Intensive Care Medicine ,Article ,Positive-Pressure Respiration ,Airway pressure release ventilation ,03 medical and health sciences ,0302 clinical medicine ,Internal medicine ,medicine ,Animals ,Positive end-expiratory pressure ,Mechanical ventilation ,Respiratory Distress Syndrome ,Lung ,business.industry ,030208 emergency & critical care medicine ,Intrapleural pressure ,Pneumonia ,respiratory system ,respiratory tract diseases ,Disease Models, Animal ,medicine.anatomical_structure ,030228 respiratory system ,Respiratory Mechanics ,Breathing ,Cardiology ,Female ,business ,circulatory and respiratory physiology ,Transpulmonary pressure - Abstract
Objectives To determine the impact of positive end-expiratory pressure during mechanical ventilation with and without spontaneous breathing activity on regional lung inflammation in experimental nonsevere acute respiratory distress syndrome. Design Laboratory investigation. Setting University hospital research facility. Subjects Twenty-four pigs (28.1-58.2 kg). Interventions In anesthetized animals, intrapleural pressure sensors were placed thoracoscopically in ventral, dorsal, and caudal regions of the left hemithorax. Lung injury was induced with saline lung lavage followed by injurious ventilation in supine position. During airway pressure release ventilation with low tidal volumes, positive end-expiratory pressure was set 4 cm H2O above the level to reach a positive transpulmonary pressure in caudal regions at end-expiration (best-positive end-expiratory pressure). Animals were randomly assigned to one of four groups (n = 6/group; 12 hr): 1) no spontaneous breathing activity and positive end-expiratory pressure = best-positive end-expiratory pressure - 4 cm H2O, 2) no spontaneous breathing activity and positive end-expiratory pressure = best-positive end-expiratory pressure + 4 cm H2O, 3) spontaneous breathing activity and positive end-expiratory pressure = best-positive end-expiratory pressure + 4 cm H2O, 4) spontaneous breathing activity and positive end-expiratory pressure = best-positive end-expiratory pressure - 4 cm H2O. Measurements and main results Global lung inflammation assessed by specific [F]fluorodeoxyglucose uptake rate (median [25-75% percentiles], min) was decreased with higher compared with lower positive end-expiratory pressure both without spontaneous breathing activity (0.029 [0.027-0.030] vs 0.044 [0.041-0.065]; p = 0.004) and with spontaneous breathing activity (0.032 [0.028-0.043] vs 0.057 [0.042-0.075]; p = 0.016). Spontaneous breathing activity did not increase global lung inflammation. Lung inflammation in dorsal regions correlated with transpulmonary driving pressure from spontaneous breathing at lower (r = 0.850; p = 0.032) but not higher positive end-expiratory pressure (r = 0.018; p = 0.972). Higher positive end-expiratory pressure resulted in a more homogeneous distribution of aeration and regional transpulmonary pressures at end-expiration along the ventral-dorsal gradient, as well as a shift of the perfusion center toward dependent zones in the presence of spontaneous breathing activity. Conclusions In experimental mild-to-moderate acute respiratory distress syndrome, positive end-expiratory pressure levels that stabilize dependent lung regions reduce global lung inflammation during mechanical ventilation, independent from spontaneous breathing activity.
- Published
- 2019