Early dobutamine response to delayed cerebral ischemia affected by vasospasm after subarachnoid hemorrhage: Serial cerebral blood flow analyses using O-15-water positron-emission tomography – A report of two cases

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Abstract
Delayed cerebral ischemia (DCI) which is mainly attributable to cerebral vasospasm, is a major cause of death and disability in patients with aneurysmal subarachnoid hemorrhage (SAH). Hemodynamic augmentation with vasopressors or inotropes is traditionally used in the clinical management of post-SAH DCI. Although the rationale for such treatment is to improve the regional cerebral blood flow (rCBF) to prevent secondary ischemia, brain-perfusion data underlying such systemic hemodynamic manipulation are limited. Here, we present two cases of SAH with symptomatic DCI caused by focal or multiple-vessel vasospasm to demonstrate the effects of dobutamine on serial rCBF measurements using 15O-labelled water positron-emission tomography. In the patient with localized proximal vasospasm, immediate rCBF uptake was observed in affected brain areas, yielding neurological improvement soon after dobutamine infusion and increasing cardiac output above normal levels. In the other patient, no rCBF responses were observed in multiple and diffuse vasospasm-affected regions, resulting in severe cerebral infarction and functional impairments. We speculate that dobutamine may act via the relief of microcirculatory disturbance attributable to vasospasm, as demonstrated by the increased velocities of circulating blood in cortical microvessels distal to the vasospasm early after infusion rather than in the spastic vessels themselves. This is the first report to present the effectiveness and limitations of the acute rCBF response to hyperdynamic therapy with dobutamine for DCI, depending on the extent and severity of the vasospasm.

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