title: Open lung approach vs acute respiratory distress syndrome network ventilation in experimental acute lung injury.
abstract: BACKGROUND
  Setting and strategies of mechanical ventilation with positive end-expiratory pressure (PEEP) in acute lung injury (ALI) remains controversial. This study compares the effects between lung-protective mechanical ventilation according to the Acute Respiratory Distress Syndrome Network recommendations (ARDSnet) and the open lung approach (OLA) on pulmonary function and inflammatory response.
  
  
  METHODS
  Eighteen juvenile pigs were anaesthetized, mechanically ventilated, and instrumented. ALI was induced by surfactant washout. Animals were randomly assigned to mechanical ventilation according to the ARDSnet protocol or the OLA (n=9 per group). Gas exchange, haemodynamics, pulmonary blood flow (PBF) distribution, and respiratory mechanics were measured at intervals and the lungs were removed after 6 h of mechanical ventilation for further analysis.
  
  
  RESULTS
  PEEP and mean airway pressure were higher in the OLA than in the ARDSnet group [15 cmH(2)O, range 14-18 cmH(2)O, compared with 12 cmH(2)O; 20.5 (sd 2.3) compared with 18 (1.4) cmH(2)O by the end of the experiment, respectively], and OLA was associated with improved oxygenation compared with the ARDSnet group after 6 h. OLA showed more alveolar overdistension, especially in gravitationally non-dependent regions, while the ARDSnet group was associated with more intra-alveolar haemorrhage. Inflammatory mediators and markers of lung parenchymal stress did not differ significantly between groups. The PBF shifted from ventral to dorsal during OLA compared with ARDSnet protocol [-0.02 (-0.09 to -0.01) compared with -0.08 (-0.12 to -0.06), dorsal-ventral gradients after 6 h, respectively].
  
  
  CONCLUSIONS
  According to the OLA, mechanical ventilation improved oxygenation and redistributed pulmonary perfusion when compared with the ARDSnet protocol, without differences in lung inflammatory response.
authors.affiliation: Department of Anesthesia and Intensive Care Therapy, University Hospital Dresden, Dresden, Germany. peter.spieth@uniklinikum-dresden.de
authors.forename: P M
authors.initials: PM
authors.lastname: Spieth
authors.forename: A
authors.initials: A
authors.lastname: Güldner
authors.forename: A R
authors.initials: AR
authors.lastname: Carvalho
authors.forename: M
authors.initials: M
authors.lastname: Kasper
authors.forename: P
authors.initials: P
authors.lastname: Pelosi
authors.forename: S
authors.initials: S
authors.lastname: Uhlig
authors.forename: T
authors.initials: T
authors.lastname: Koch
authors.forename: M
authors.initials: M
authors.lastname: Gama de Abreu
mesh_terms: D055371:Acute Lung Injury / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*; D000818:Animals; D005260:Female; D015850:Interleukin-6 / Q000235:genetics; D016209:Interleukin-8 / Q000097:blood; D008168:Lung / Q000473:pathology; D011175:Positive-Pressure Respiration; D011652:Pulmonary Circulation; D011659:Pulmonary Gas Exchange; D012333:RNA, Messenger / Q000032:analysis; D012121:Respiration, Artificial / Q000379:methods*; D012128:Respiratory Distress Syndrome / Q000628:therapy*; D013314:Stress, Mechanical; D013552:Swine
chemical_list: D015850:Interleukin-6; D016209:Interleukin-8; D012333:RNA, Messenger