Increased survival with hypotensive resuscitation in a rabbit model of uncontrolled hemorrhagic shock in pregnancy

Abstract

Aim: We sought to compare the effects of conservative hypotensive and aggressive normotensive resuscitation strategies on blood loss, fluid requirements, blood lactate and survival rate in a clinically relevant model of uncontrolled hemorrhagic shock in pregnancy.

Method: 60 anesthetized New Zealand white rabbits at late gestation underwent uncontrolled hemorrhagic shock by transecting a small artery in the mesometrium, followed by blood withdrawal via the carotid artery, to a mean arterial pressure (MAP) of 40-45mmHg. They were randomly divided into six groups (n=10 per group): sham shock (group SS); shock without resuscitation (group SH); hypotensive resuscitation in the simulated prehospital phase with Ringer's solution to MAP of 50, 60, or 70mmHg, respectively (groups RE50, RE60, RE70); and aggressive resuscitation in the prehospital phase with Ringer's solution to MAP of 80mmHg (group RE80). Finally, in the simulated hospital phase, animals in the resuscitated groups underwent surgical control of bleeding and were fully resuscitated with half of the heparinized shed blood and Ringer's solution to MAP of 80mmHg.

Results: Hypotensive resuscitation significantly decreased blood loss and subsequent volume infusion, leading to higher hematocrit, lower lactate concentration, and shorter prothrombin time and activated partial thromboplastin time. Median survival time in group RE60 (4.3+/-0.6 days) was significantly longer than that in groups RE50 (2.7+/-0.4 days), RE70 (2.3+/-0.3 days), and RE80 (1.7+/-0.3 days) (P<0.05).

Conclusions: We conclude that in this rabbit model of uncontrolled hemorrhage in pregnancy, hypotensive resuscitation to MAP of 60mmHg may be an optimal target MAP before hemorrhage can be controlled by surgical intervention.