The effects of hemoglobin glutamer-200 (bovine) on the microcirculation ina canine hypovolemia model: A noninvasive computer-assisted intravital microscopy study

We sought to correlate in vivo microvascular, systemic function, hemodynami c, and oxygenation changes in autologous shed blood (n = 4) and hemoglobin glutamer-200 (Hb-200) (ii = 4) resuscitations in hypovolemic dogs. Hemorrha ge (similar to 40% blood loss) reduced mean arterial pressure to similar to 50 = Hg and caused significant (P < 0.01) decreases in hematocrit, total h emoglobin, mean pulmonary arterial pressure, cardiac output, and oxygen del ivery and significant (P < 0.01) increases in heart rate, systemic vascular resistance, and lactic acidosis. Significant (P < 0.01) changes in conjunc tival microvascular variables also occurred, including a 19% decrease in ve nular diameter and 79% increase in average blood flow velocity. Shed blood resuscitation returned microvascular, systemic function, hemodynamic, and o xygenation variables to prehemorrhagic baseline values. In contrast, Hb-200 failed to restore hematocrit, total hemoglobin, cardiac output, oxygen del ivery index, and systemic venous resistance to baseline, but it restored ot her systemic functions and all hemodynamic and microvascular changes. In ad dition, Hb-200 resuscitation in hypovolemic dogs (similar to 40% blood loss ) did not cause extreme hemodilution or fatal outcome. This study confirms that real-time (in vivo) microvascular studies, which were conducted only i n small rodent models in the past, can be performed simultaneously with sys temic function, hemodynamic, and oxygenation studies in a large animal mode l for relevant data correlation.