Polymerized bovine hemoglobin can improve small-volume resuscitation from hemorrhagic shock in hamsters

Systemic and microvascular hemodynamic responses to hemorrhagic shock volume resuscitation with hypertonic saline followed by infusion of polymerized bovine hemoglobin (PBH) at different concentrations were studied in the hamster window chamber model to determine the role of plasma oxygen-carrying capacity and vasoactivity during resuscitation. Moderate hemorrhagic shock was induced by arterial controlled bleeding of 50% of blood volume (BV), and a hypovolemic state was maintained for 1 h. Volume was restituted by infusion of hypertonic saline (7.5% NaCl), 3.5% of BV, followed by 10% of BV of PBH at 2 different concentrations. Resuscitation was followed for 90 min and was carried out using 13 gPBH/dL (PBH13), PBH diluted to 4 gPBH/dL in albumin solution at matching colloidal osmotic pressure (PBH4), and an albumin-only solution at matching colloidal osmotic pressure (PBH0). Systemic parameters, microvascular hemodynamics, and functional capillary density were determined during hemorrhage, hypovolemic shock, and resuscitation. The PBH13 caused higher arterial pressure without reverting vasoconstriction and hypoperfusion. The PBH4 and PBH0 had lower MAP and partially reverted vasoconstriction. Only treatment with PBH4 restored perfusion and functional capillary density when compared with PBH13 and PBH0. Blood gas parameters and acid-base balance recovered proportionally to microvascular perfusion. Tissue PO2 was significantly improved in the PBH4 group, showing that limited restoration of oxygen-carrying capacity is beneficial and compensates for the effects of vasoactivity, a characteristic of molecular hemoglobin solutions proposed as blood substitutes.