Low-volume
resuscitation with hypertonic (7.5%) saline (HTS) is an evolving therapeutic modality for patients with
hemorrhagic shock. This
solution has been shown to exert protective hemodynamic effects in models of controlled
hemorrhagic shock and in several clinical trials. However, HTS has no
oxygen-carrying capacity and therefore does not improve
oxygen delivery directly. One of the leading strategies in developing an
oxygen-carrying resuscitative fluid is the encapsulation of
hemoglobin within
phospholipid vesicles (LEH). This preparation has the advantage of being blood type and
antigen free, easily adaptable to scale-up production, and remarkably stable with a long shelf life. We therefore tested the hypothesis that lyophilized LEH reconstituted with HTS will improve tissue oxygenation and survival in rats exposed to a lethal controlled
hemorrhagic shock.
Shock was induced by withdrawal of 70% of blood volume and
therapy (n = 10-16) with HTS (5 mL/kg), LEH (5 mL/kg),
lactated Ringer's solution (vol:vol = 1:3), LEH-HTS (5 mL/kg), or
oxygen (100%) was initiated 15 minutes later. The LEH-HTS improved skeletal muscle
oxygen tension directly measured using a thin-film chamber
oxygen sensor (PO2 87 +/- 13 mm Hg vs. 40-50 mm Hg in other groups, p < 0.05). This was associated with improved blood pressure, reduced
acidosis, and increased survival at 24 hours (75% vs. 6%-25% in other groups, p < 0.05). In conclusion, the study demonstrates a remarkably salutary effect of LEH reconstituted with HTS as a
blood substitute in the treatment of
hemorrhagic shock.