Hemoglobin-vesicles suspended in recombinant human serum albumin for resuscitation from hemorrhagic shock in anesthetized rats

Objective: Hemoglobin-vesicle (HbV) has been developed to provide oxygen-carrying ability to plasma expanders. Its ability to restore the systemic condition after hemorrhagic shock was evaluated in anesthetized Wistar rats for 6 hrs after resuscitation. The HbV was suspended in 5 g/dL recombinant human serum albumin (HbV/rHSA) at an Hb concentration of 8.6 g/dL. Design: Prospective, randomized, controlled trial. Setting: Department of Surgery, School of Medicine, Keio University. Subjects: Forty male Wistar rats. Interventions: The rats were anesthetized with 1.5% sevoflurane inhalation throughout the experiment Polyethylene catheters were introduced through the right jugular vein into the right atrium for infusion and into the right common carotid artery for blood withdrawal and mean arterial pressure monitoring. Measurements and Main Results: Shock was induced by 50% blood withdrawal. The rats showed hypotension (mean arterial pressure = 32 ± 10 mm Hg) and significant metabolic acidosis and hyperventilation. After 15 mins, they received HbV/rHSA, shed autologous blood (SAB), washed homologous red blood cells (wRBC) suspended in rHSA (wRBC/rHSA, [Hb] = 8.6 g/dL), or rHSA alone. The HbV/rHSA group restored mean arterial pressure to 93 ± 8 mm Hg at 1 hr, similar to the SAB group (92 ± 9 mm Hg), which was significantly higher compared with the rHSA (74 ± 9 mm Hg) and wRBC/rHSA (79 ± 8 mm Hg) groups. There was no remarkable difference in the blood gas variables between the resuscitated groups; however, two of eight rats in the rHSA group died before 6 hrs. After 6 hrs, the rHSA group showed significant ischemic changes in the right cerebral hemisphere relating to the ligation of the right carotid artery followed by cannulation, whereas the HbV/rHSA, SAB, and wRBC/rHSA groups showed less changes. Conclusions: HbV suspended in recombinant human serum albumin provides restoration from hemorrhagic shock that is comparable with that using shed autologous blood.