Influence of negative expiratory pressure ventilation on hemodynamic variables during severe hemorrhagic shock.
OBJECTIVE
Outcome after trauma with severe hemorrhagic shock is still dismal. Since the majority of blood is present in the venous vessels, it might be beneficial to perform venous recruiting via the airway during severe hemorrhagic shock. Therefore, the purpose of our study was to evaluate the effects of negative expiratory pressure ventilation on mean arterial blood pressure, cardiac output, and short-term survival during severe hemorrhagic shock.


METHODS
Prospective study in 21 laboratory animals.


METHODS
University hospital research laboratory.


METHODS
: Tyrolean domestic pigs.


METHODS
After induction of controlled hemorrhagic shock (blood loss approximately 45 mL/kg), 21 pigs were randomly ventilated with either zero end-expiratory pressure (0 PEEP; n = 7), 5 cm H2O positive end-expiratory pressure (5 PEEP; n = 7), or negative expiratory pressure ventilation (up to -30 cm H2O at the endotracheal tube during expiration; n = 7).


RESULTS
Mean (+/-sd) arterial blood pressure was significantly higher in the negative expiratory pressure ventilation swine when compared with the 0 PEEP (38 +/- 5 vs. 27 +/- 3 mm Hg; p = .001) and the 5 PEEP animals (38 +/- 5 vs. 20 +/- 6 mm Hg; p < .001) after 5 mins of the experiment. Cardiac output was significantly higher in the negative expiratory pressure ventilation swine when compared with the 0 PEEP (3.1 +/- .4 vs. 1.9 +/- .9 L/min; p = .001) and 5 PEEP animals (3.1 +/- .4 vs. 1.2 +/- .8 L/min; p < .001) after 5 mins of the experiment. All seven negative expiratory pressure ventilation animals, but only three of seven 0 PEEP animals (p = .022), survived the 120-min study period, whereas all seven of seven 5 PEEP animals were dead within 35 mins (p < .001). Limitations include that blood loss was controlled and that the small sample size limits the evaluation of survival outcome.


CONCLUSIONS
When compared with pigs ventilated with either 0 PEEP or 5 PEEP, negative expiratory pressure ventilation during severe hemorrhagic shock improved mean arterial blood pressure and cardiac output.
Krismer
Anette C
AC
Department of Anesthesiology and Critical Care Medicine, Innsbruck Medical University, Innsbruck, Austria.
Wenzel
Volker
V
Lindner
Karl H
KH
von Goedecke
Achim
A
Junger
Martin
M
Stadlbauer
Karl H
KH
Königsrainer
Alfred
A
Strohmenger
Hans-U
HU
Sawires
Martin
M
Jahn
Beate
B
Hörmann
Christoph
C
D000818:Animals; D016280:Atrial Function, Right / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D002245:Carbon Dioxide / Q000097:blood; D002302:Cardiac Output / Q000502:physiology*; D004195:Disease Models, Animal; D011175:Positive-Pressure Respiration / Q000379:methods*; D011446:Prospective Studies; D011897:Random Allocation; D012771:Shock, Hemorrhagic / Q000503:physiopathology / Q000628:therapy*; D016019:Survival Analysis; D013552:Swine
D002245:Carbon Dioxide