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

UNLABELLED

We sought to correlate in vivo microvascular, systemic function, hemodynamic, and oxygenation changes in autologous shed blood (n = 4) and hemoglobin glutamer-200 (Hb-200) (n = 4) resuscitations in hypovolemic dogs. Hemorrhage (approximately 40% blood loss) reduced mean arterial pressure to approximately 50 mm Hg and caused significant (P < 0.01) decreases in hematocrit, total hemoglobin, mean pulmonary arterial pressure, cardiac output, and oxygen delivery and significant (P < 0.01) increases in heart rate, systemic vascular resistance, and lactic acidosis. Significant (P < 0.01) changes in conjunctival microvascular variables also occurred, including a 19% decrease in venular diameter and 79% increase in average blood flow velocity. Shed blood resuscitation returned microvascular, systemic function, hemodynamic, and oxygenation variables to prehemorrhagic baseline values. In contrast, Hb-200 failed to restore hematocrit, total hemoglobin, cardiac output, oxygen delivery index, and systemic venous resistance to baseline, but it restored other systemic functions and all hemodynamic and microvascular changes. In addition, Hb-200 resuscitation in hypovolemic dogs (approximately 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 in small rodent models in the past, can be performed simultaneously with systemic function, hemodynamic, and oxygenation studies in a large animal model for relevant data correlation.

IMPLICATIONS

This is the first time that changes in the blood circulation have been studied, quantified, and correlated with systemic function, hemodynamic, and oxygenation changes in shock and during shock treatment in a large animal model. This study was performed by a new technology developed in-house to noninvasively and quantitatively study blood vessels in real time.