ACUTE CEREBRAL BLOOD-FLOW RESPONSE TO DOPAMINE-INDUCED HYPERTENSION AFTER SUBARACHNOID HEMORRHAGE

The effects of dopamine-induced hypertension on local cerebral blood f low (CBF) were investigated in 13 patients suspected of suffering clin ical vasospasm after aneurysmal subarachnoid hemorrhage (SAH). The CBF was measured in multiple vascular territories using xenon-enhanced co mputerized tomography (CT) with and without dopamine-induced hypertens ion. A territorial local CBF of 25 ml/100 gm/min or less was used to d efine ischemia and was identified in nine of the 13 patients. Raising mean arterial blood pressure from 90 +/- 11 mm Hg to 111 +/- 13 mm Hg (p < 0.05) via dopamine administration increased territorial local CBF above the ischemic range in more than 90% of the uninfarcted territor ies identified on CT while decreasing local CBF in one-third of the no nischemic territories. Overall, the change in local CBF after dopamine -induced hypertension was correlated with resting local CBF at normote nsion and was unrelated to the change in blood pressure. Of the 13 pat ients initially suspected of suffering clinical vasospasm, only 54% ha d identifiable reversible ischemia. The authors conclude that dopamine -induced hypertension is associated with an increase in flow in patien ts with ischemia after SAH. However, flow changes associated with dopa mine-induced hypertension may not be entirely dependent on changes in systemic blood pressure. The direct cerebrovascular effects of dopamin e may have important, yet unpredictable, effects on CBF under clinical pathological conditions. Because there is a potential risk of dopamin e-induced ischemia, treatment may be best guided by local CBF measurem ents.