Fluid Resuscitation of Hemorrhagic Shock with Hemoglobin Vesicles in Beagle Dogs: Pilot Study

Resuscitation of hemorrhagic shock requires volume replacement and restoration of oxygen metabolism. Artificial oxygen carriers that can both expand blood volume and deliver oxygen have been developed as resuscitation fluids. We employed hemoglobin vesicles (HbV), a cellular-type artificial oxygen carrier, in a Beagle dog hemorrhagic shock model to prove the efficacy of HbV. Hemorrhagic shock was introduced in splenectomized Beagle dogs by withdrawing 50% of circulating blood from the femoral artery. Shock was maintained for 60 minutes before isovolemic resuscitation with HbV dispersed in 5% albumin in saline (HbV), lactated Ringer's solution (LR), 5% human serum albumin in saline (HSA), or autologous shed blood (ASB). One animal in the LR group died 150 min after resuscitation. All other animals survived 4 h of the experiment. The mean arterial pressure remained significantly lower in the LR group than in the HbV group but did not differ significantly among the HbV, Alb, and ASB groups. Immediately after resuscitation, the HbV group showed a significantly higher mean pulmonary arterial pressure, which decreased within 10 minutes to the baseline level. The cardiac output was significantly higher in the Alb group than in the others, indicating compensation for low oxygen delivery per unit blood. The post-resuscitation hematocrit was 36% in the ASB group and decreased in the other groups (20-22%). Serum chemistry data from the HbV group were unremarkable. HbV contributed 32% of the post-resuscitation oxygen delivery. Collectively, HbV is comparable to ASB and HSA as a resuscitation fluid and is an effective oxygen carrier.