INCREASED VASCULAR-RESISTANCE WITH HEMOGLOBIN-BASED OXYGEN CARRIERS

Purpose: To compare the effects of resuscitation with hemoglobin-based oxygen-carriers and conventional resuscitation fluids on hemodynamics , oxygen transport, and oxygen consumption in an animal model of the u se of these fluids in the treatment of hemorrhagic shock. Protocol: Tw enty-eight immature swine were surgically prepared, allowed to recover five days, water deprived for 48 hours, hemorrhaged of 25 ml/kg over one hour, resuscitated promptly with 1) Ringer's lactate, 75 ml/kg, 2) 7% albumin in Ringer's acetate, 25 ml/kg, 3) 9% unmodified hemoglobin in Ringer's acetate, 25 ml/kg, or 4) 9% cra-crosslinked hemoglobin in Ringer's acetate, 25 ml/kg, and observed with three hours of hemodyna mic and oxygen transport measurements. Results: Systemic and pulmonary vascular resistance were increased in hemoglobin-treated animals to m ore than twice the levels seen in crystalloid- or colloid-treated cont rols. Oxygen consumption and the rate of correction of lactic acidosis were not increased in hemoglobin-treated animals. Conclusions: Increa sed vascular resistance limits the oxygen transport benefit of cell-fr ee-hemoglobin-based oxygen carriers. Cell-free-hemoglobin-induced incr eases in vascular resistance may place animals' hearts on an unfavorab le portion of the Frank-Starling curve as well as complicate further m edical treatment by reducing the animals' tolerance to increases in bl ood viscosity.