Correlative aspects of hypervolemic hemodilution: low-molecular-weight dextran infusions after experimental cerebral arterial occlusion.

Unilateral clipping of cerebral arteries in eight dogs reduced regional cortical blood flow (rCoBF) without altering cardiac output (CO) or intracranial pressure (ICP) and resulted in 10% hemispheric infarction. In ten dogs, total blood volume (TBV), CO, rCoBF in the region of the occluded artery, and ICP increased while the hematocrit (Hct) decreased following two low-molecular-weight dextran (D40) infusions. Hemispheric infarction was 4%. The CO, rCoBF, and ICP correlated directly with TBV, but inversely with Hct, while rCoBF correlated positively with CO. Two similar hemodiluting D40 infusions in nine control dogs raised TBV, CO, and ICP but not rCoBF. The CO, rCoBF, and ICP correlated positively with TBV but inversely with Hct while rCoBF correlated with CO. Thus, hypervolemic hemodilution with D40 enhances collateral perfusion to acutely ischemic regions of brain distal to segmental arterial occlusions and concomitantly augments CO and ICP. Correlations between CO and cerebral blood flow after D40 infusion may be secondary to lowered Hct.