title: Influence of positive end-expiratory pressure ventilation on survival during severe hemorrhagic shock.
abstract: OBJECTIVE
  Although a moderate positive end-expiratory pressure (PEEP) level is widely recommended, it is unknown whether moderate PEEP during mechanical ventilation has adverse effects during severe hemorrhagic shock. Therefore, the purpose of our study was to evaluate the effects of 0 cm H2O PEEP versus 5 cm H2O PEEP versus 10 cm H2O PEEP on short-term survival in a porcine model of severe hemorrhagic shock. Secondary study endpoints were hemodynamic variables and blood gases.
  
  
  METHODS
  Twenty-four anesthetized pigs were bled approximately 45 mL/kg, randomized into 3 groups, and then ventilated with 0, 5, or 10 cm H2O PEEP. Survival rates were compared using Kaplan-Meier methods with log rank (Mantel Cox) comparison of cumulative survival by treatment group.
  
  
  RESULTS
  Seven of 8 0 cm H2O PEEP animals survived the 120-minute study period, but 8 of 8 5 cm H2O PEEP animals died within 30 minutes, and 8 of 8 10 cm H2O PEEP animals were dead within 20 minutes (P<.0001). Ventilation with 0 cm H2O PEEP prevented a further reduction of mean arterial blood pressure and cardiac output. When compared with the 0 cm H2O PEEP group, end-tidal CO2 declined in the 5 cm H2O PEEP and 10 cm H2O PEEP animals. Compared with the 0 cm H2O PEEP animals, those ventilated with 5 or 10 cm H2O PEEP had higher lactate levels after 10 minutes.
  
  
  CONCLUSIONS
  When compared with pigs ventilated with either 5 or 10 cm H2O PEEP, those ventilated with 0 cm H2O PEEP during untreated, severe hemorrhagic shock had significantly improved short-term survival.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Innsbruck Medical University, Innsbruck, Austria. anette.krismer@uibk.ac.at
authors.forename: Anette C
authors.initials: AC
authors.lastname: Krismer
authors.forename: Volker
authors.initials: V
authors.lastname: Wenzel
authors.forename: Karl H
authors.initials: KH
authors.lastname: Lindner
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Haslinger
authors.forename: Stephan
authors.initials: S
authors.lastname: Oroszy
authors.forename: Karl H
authors.initials: KH
authors.lastname: Stadlbauer
authors.forename: Alfred
authors.initials: A
authors.lastname: Königsrainer
authors.forename: Brian
authors.initials: B
authors.lastname: Boville
authors.forename: Christoph
authors.initials: C
authors.lastname: Hörmann
mesh_terms: D000818:Animals; D001784:Blood Gas Analysis; D004195:Disease Models, Animal; D004635:Emergency Medicine / Q000379:methods; D006439:Hemodynamics; D011175:Positive-Pressure Respiration / Q000379:methods*; D011897:Random Allocation; D012771:Shock, Hemorrhagic / Q000097:blood / Q000503:physiopathology / Q000628:therapy*; D016019:Survival Analysis; D013552:Swine; D016896:Treatment Outcome