Blood volume expansion with hetastarch in acute ischaemic stroke: the effects on local cerebral blood flow and computer mapped EEG

Focal cerebral ischaemia was induced in seven anaesthetized monkeys by unilateral middle cerebral artery (MCA) occlusion. Local cerebral blood flow (CBF) and computer mapped EEG (CME) changes were then studied as blood volume and cardiac output (CO) were varied. CO was increased by colloidal volume expansion and decreased by exsanguination. Local CBF fell to 24 +/- 9% of control values in ischaemic areas following MCA occlusion and increased to 43 +/- 19% of control values (p less than 0.01) when CO was increased by 130 +/- 70% with colloid infusion. Local CBF to nonischaemic regions was not altered significantly by blood volume expansion. Exsanguination led to return of CO to control levels and was associated with reduction of local CBF in ischaemic regions to 24 +/- 12% of control values (p less than 0.05). CME showed bifrontal or ipsilateral slow wave foci (delta) following MCA occlusion. Blood volume expansion brought about a marked reduction of this slow wave activity and exsanguination led to recurrence of the slow wave foci. This data demonstrated that colloidal blood volume expansion induced an increase in local CBF and improved neuroelectric status of ischaemic brain following MCA occlusion. It was also shown that a reduction of blood volume and cardiac output resulted in a reduction in local CBF and a worsening of neuroelectric status in ischaemic areas. This study supports the contention that blood volume and cardiac output maintenance is extremely important in the management of acute ischaemic stroke.