Influence of positive end-expiratory pressure ventilation on survival during severe hemorrhagic shock.
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.
Krismer
Anette C
AC
Department of Anesthesiology and Critical Care Medicine, Innsbruck Medical University, Innsbruck, Austria. anette.krismer@uibk.ac.at
Wenzel
Volker
V
Lindner
Karl H
KH
Haslinger
Christopher W
CW
Oroszy
Stephan
S
Stadlbauer
Karl H
KH
Königsrainer
Alfred
A
Boville
Brian
B
Hörmann
Christoph
C
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