title: Time course of lung inflammatory and fibrogenic responses during protective mechanical ventilation in healthy rats.
abstract: This study aimed to assess pulmonary inflammatory and fibrogenic responses and their impact on lung mechanics and histology in healthy rats submitted to protective mechanical ventilation for different experimental periods. Eighteen Wistar rats were randomized to undergo open lung-mechanical ventilation (OL-MV) for 1, 6 or 12 h. Following a recruitment maneuver, a decremental PEEP trial was performed and PEEP set according to the minimal respiratory system static elastance. Respiratory system, lung, and chest-wall elastance and gas-exchange were maintained throughout the 12 h experimental period. Histological lung injury score remained low at 1 and 6 h, but was higher at 12 h due to overinflation. A moderate inflammatory response was observed with a distinct peak at 6h. Compared to unventilated controls, type I procollagen mRNA expression was decreased at 1 and 12h, while type III procollagen expression decreased throughout the 12h experimental period. In conclusion, OL-MV in healthy rats yielded overinflation after 6 h even though respiratory elastance and gas-exchange were preserved for up to 12 h.
authors.affiliation: Department of Anaesthesiology and Critical Care Medicine, University Hospital Mannheim, Faculty of Medicine, University of Heidelberg, Theodor-Kutzer Ufer 1-3, 68165 Mannheim, Germany.
authors.forename: Joerg
authors.initials: J
authors.lastname: Krebs
authors.forename: Paolo
authors.initials: P
authors.lastname: Pelosi
authors.forename: Charalambos
authors.initials: C
authors.lastname: Tsagogiorgas
authors.forename: Jenny
authors.initials: J
authors.lastname: Haas
authors.forename: Benito
authors.initials: B
authors.lastname: Yard
authors.forename: Patricia R M
authors.initials: PR
authors.lastname: Rocco
authors.forename: Thomas
authors.initials: T
authors.lastname: Luecke
mesh_terms: D055371:Acute Lung Injury / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control; D000818:Animals; D008168:Lung / Q000473:pathology* / Q000502:physiology; D008297:Male; D011175:Positive-Pressure Respiration / Q000379:methods*; D011658:Pulmonary Fibrosis / Q000473:pathology* / Q000503:physiopathology / Q000517:prevention & control*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D012121:Respiration, Artificial / Q000379:methods; D015656:Respiratory Mechanics / Q000502:physiology*; D013997:Time Factors