Effect of the cellular-type artificial oxygen carrier hemoglobin vesicle as a resuscitative fluid for prehospital treatment: experiments in a rat uncontrolled hemorrhagic shock model.

The hemoglobin vesicle (Hb-vesicle) is a cellular-type artificial oxygen carrier showing a resuscitative effect comparable to that of blood transfusion in several animal models. However, the efficacy of Hb-vesicles for resuscitation when the hemorrhage cannot be controlled remains unclear. Therefore, we used Hb-vesicles in a rat hemorrhagic shock model caused by continuous bleeding. For inducing uncontrolled hemorrhage, animals were heparinized and bled from the caudal artery. Fluid resuscitation was subsequently performed with five materials: Hb-vesicle suspension in a 5% albumin (Alb) solution (HbV), washed red blood cells (wRBC) in a 6% hydroxyethyl starch (HES) solution, 5% Alb, 6% HES, and saline (Sal). During the experiment, all animals in the HbV and wRBC groups survived, whereas all those in the Alb and HES groups died. In the Sal group, five of seven animals died. In the HbV and wRBC groups, the heart rate, mean arterial pressure, and blood lactic acid levels were stabilized during resuscitation. Meanwhile, the hematocrit levels of the HbV, Alb, and HES groups showed sharp decreases (HbV: 6.8% ± 1.7%, Alb: 6.8% ± 0.8%, HES: 5.5% ± 0.7% at 100% total circulated blood volume; final hematocrit of the HbV group: 1.5% ± 0.5%). These results suggest that shocked animals can survive longer when the Hb-vesicle supply is maintained and that HbV showed a similar effect to wRBC in maintaining the circulating volume and oxygen metabolism. Continuous infusion of Hb-vesicles may extend the survival of trauma victims with uncontrolled hemorrhage until they have reached a trauma center.