Colloidal volume expansion during acute cerebral ischaemia: assessed by local cerebral blood flow and computerized...

Colloidal volume expansion during acute cerebral ischaemia was assessed by local cerebral blood flow (CBF) and the power ratio index (PRI) in 8 anaesthetized Macaque monkeys. Focal cerebral ischaemia was produced by right middle cerebral artery occlusion. The animals were then volume expanded (to maximum cardiac output) with 6% hetastarch and then exsanguinated to baseline cardiac output. During volume expansion, local CBF in the ischaemic hemisphere increased from 25 +/- 12 to 39 +/- 23 cc/100 g/min (p less than 0.01) and during exsanguination decreased to 32 +/- 18 cc/100 g/min. Local CBF did not change significantly in the nonischaemic hemisphere. EEG power data, as assessed by PRI [(delta + theta power/alpha + beta power) x 100] changed significantly during blood volume manipulation. The mean PRI value in the right hemisphere deteriorated by increasing from 65 +/- 22 to 94 +/- 25 (p less than 0.01) following vessel occlusion but improved by decreasing to 81 +/- 23 (p less than 0.05) following volume expansion. Following exsanguination, the PRI value increased to 87 +/- 21. These data demonstrate the benefits of volume expansion during acute cerebral ischaemia. Changes in local CBF were consistently associated with changes in the PRI maps and values.