Study on the Optimal Dosage of Mannitol in Aneurysmal Subarachnoid Hemorrhage Craniotomy

Aneurysmal subarachnoid hemorrhage (aSAH) tended to lead to a sudden increase in intracerebral pressure (ICP), which can cause decreased cerebral perfusion and transient global cerebral ischemia. Early clipping and coiling of aneurysms and surgical evacuation of intracerebral hematoma were recommended for aSAH patients. However, the high ICP made it difficult to separate the subarachnoid space during the operation. Effective reduction of ICP was the key to the succession of the operation. But there is a lack of consensus on the management of raised ICP in aSAH. Mannitol is widely used to reduce ICP in patients with cerebral edema. The potential mechanism including decreasing the viscosity of the blood improving regional cerebral microvascular flow and oxygenation and increasing intravascular volume due to increased plasma osmolality. The magnitude of the pressure reduction was correlated with the intact intracranial automatic adjustment function. However, the hypochloremic metabolic alkalosis, hypernatremia, hypokalemia and renal failure associated with mannitol overdose must be considered and the effective dose and the duration of its administration were still unknown. The aims of this study were to determine the most appropriate mannitol dose to provide adequate brain relaxation in aSAH patients with the fewest adverse effects.