Hyperosmotic-hyperoncotic versus hyperosmotic-hyperviscous: small volume resuscitation in hemorrhagic shock

The aim of this study was to test the effects of using a high-viscosity fluid after small-volume hyperosmotic resuscitation from hemorrhagic shock and to compare this to hyperosmotic followed by hyperoncotic resuscitation. Studies were made in the awake hamster window chamber preparation with the animals subjected to hemorrhage of 50% of blood volume and resuscitated with a small volume of a 7.5% NaCl solution, which was followed within minutes by infusion of 25% of withdrawn volume of either 0.7% or 0.8% alginate solutions (A0.7%, 7.6 cp; and A0.8%, 10.2 cp) or 5% hydroxyethyl starch (HES 5%, 2.1 cp). All modalities of resuscitation returned blood pressure to near baseline values in 5 min, which remained elevated after 90 min with A0.7% and A0.8% but returned to near shock values in 15 min with HES 5%. Microvascular flow and functional capillary density (FCD) followed the same pattern, being significantly higher for the alginate solutions than HES 5% after 90 min. Plasma viscosity 90 min after resuscitation was 2.1 and 2.6 cp for A0.7% and A0.8%, respectively, and 1.1 cP for HES 5%. There was an apparent directly proportional relationship between the concentration of alginate and blood pressure recovery, with blood pressure near normal with A0.8%, and approximately 20 mmHg lower with A0.7%. The recovery of microvascular flow and FCD, although showing a trend toward being more effective with A0.8%, was not significantly different from A0.7% but statistically different and improved relative to HES 5%. The high-viscosity fluids provide a novel small-volume method of resuscitation that maximizes microvascular perfusion for extended periods until surgical control of bleeding is possible. Results show that high-plasma-viscosity resuscitation provides a more consistent and prolonged resuscitation than hyperoncotic treatment. The increase in viscosity presents a gradual recovery in blood pressure and may be used as an alternative for small-volume hypotensive resuscitation, increasing tissue perfusion while potentially limiting hemorrhage in vascular injuries of the major blood vessels.