40. 脳動脈瘤手術中の一時的血流遮断時 (temporary clipping) における mannitol の脳保護作用機序について

抄録

The effect of mannitol on the cerebral circulation and on the circulating blood was examined in the cerebral ischemia following the vasospasm due to ruptured cerebral aneurysm. Three hundred ml of 20% mannitol solution was used by drip infusion for 30 min through this experiment, and the same volume of physiological saline solution was used for the controls. For the measurement of cerebral circulation, the mean transit time of the hemisphere was calculated by the bolus injection of 20 mCi of ^99mTcO₄^-. The mean transit time of the ischemic brain was 7.22±0.22 sec, while this was shortened to 6.55±0.25 sec after the mannitol infusion.
The influence of mannitol for hyperfunction of platelet was shown by the measurement of platelet adhesiveness. The statistically significant decrease of the platelet adhesiveness was observed after the infusion of mannitol, inspite of the slight decrease of it in case of controls using physiological saline.
RBC aggregation measured by RBC aggregometer was high in SAH patients. This increased aggregation of erythrocytes was improved after the use of mannitol. These results showed that the mannitol might contribute to the improvement of microcirculation in the ischemic brain through either the increasing effect of CBF or the correction of intravascular components.