Cerebral hemodynamics and viscoelastic property in brain edema

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The objective of this study was to examine the time course of cerebral hemodynamics and viscoelastic property in the brain edema, and to analyse the mechanism of mannitol effect on improving pressure-volume status in brain edema.Anesthetized cats were used for this study. Brain edema was produced in right frontal white matter by direct infusion technique (0.25ml/120min) described by Marmarou. Mannitol was administered 2g/Kg/3min intravenously following brain edema. CBF and CBV were monitored by Laser flow method. ICP, PVIcsf, PVItissue, and PVI-ratio (PVIcsf/PvItissue) were obtained.The presence of an edema generator elicits a continuous reduction of CBV and a transient reduction of CBF. With cessation of this mechanical force of edema production, CBV and CBF return to control. PVI-ratio tended to decrease after edema formation. Mannitol increased CBF, CBF, PVIcsf and PVI-ratio. The Improvement of the Intracranial Pressure volume status might be due to an increase in CBF as well as ICP reduction.Although viscoelastic property in the brain tissue was estimated by measuring PVI-ratio, the method of tissue pressure measurement used in this experiment was not enough sensitive to obtain significant values.