Hemoglobin solutions are potential resuscitative fluids with volume expanding and
oxygen delivery abilities developed to reduce the use of
blood transfusion. Most
hemoglobin solutions in clinical trials increase transiently arterial pressure by inhibiting
nitric oxide-dependent vasodilation. Our objective was to compare the effects on central hemodynamics and carotid blood flow of two
hemoglobin solutions after
resuscitation from
hemorrhage in anesthetized guinea pigs. After
anesthesia and instrumentation, severe
hemorrhage was induced by withdrawing 50% of the blood volume.
Resuscitation was performed after 15 min of
hypovolemia with 5%
albumin,
stroma-free hemoglobin, or
hemoglobin conjugated to
dextran-benzenetetracarboxylate (
Dex-BTC-Hb). The mean arterial pressure (MAP), carotid blood flow (CBF), vascular resistance index and heart rate (HR) were monitored for 3 hours after
resuscitation. After
hemorrhage, MAP and CBF dropped to 57.6 +/- 4.4% and 58.9 +/- 3.7% of control values respectively.
Albumin failed to maintain hemodynamics in the decompensatory phase of
shock. Both
hemoglobin solutions gave rise to a transient increase in MAP (35%);
stroma-free hemoglobin increased the CBF (150%) and resistance index (24%) whereas
Dex-BTC-Hb had no effect on CBF and vascular resistances. None of the solutions affected the HR. Modified
hemoglobin has attenuated effects on CBF and resistance index compared to
stroma-free hemoglobin. This may be due to a balance between the stimulation of
nitric oxide synthesis by shear-stress and the inhibition of vasodilation by
nitric oxide trapping.