The effects of hyperdynamic therapy on patients with cerebral vasospasm following subarachnoid hemorrhage (SAH), under normal blood pressure (BP) and normal blood volume conditions, are reported. Forty-four patients, who underwent surgery for aneurysms in acute stage, received hydroxyethyl starch (500 ml/day) postoperatively to prevent dehydration. Twenty-four of the 44 patients with prominent SAH on the computed tomographic (CT) scan, anticipating to develop cerebral ischemia due to vasospasm, were given dobutamine (DOB). The BP was maintained within the normal range, and the heart rate was kept below 130/min. In the 24 patients treated with DOB, cerebral blood flow (CBF) was measured repeatedly by the 133Xe intravenous injection method. In 8 of these 24 patients, the cardiovascular function was monitored with Swan-Ganz (S-G) catheters. Twelve of the 44 patients (27%) developed delayed neurological deficits associated with cerebral vasospasm. The neurological deficits were reversed by the administration of DOB, at a dose of 8-25 (average 12.4) micrograms/kg/min. In 43 patients, the ischemic lesions associated with vasospasm did not appear on CT scan and the patients were of normal condition at discharge. However, one patient showed multiple low-density lesions on CT scan. This was because of the failure of hyperdynamic therapy due to pulmonary complications. No case of pulmonary edema or heart failure due to volume overload was noted. In the 24 patients with prominent SAH, CBF increased significantly by up to 20% following DOB administration, although the BP stayed in the normal range.(ABSTRACT TRUNCATED AT 250 WORDS)