The Optimal Dose of Mannitol for Intraoperative Brain Relaxation During the Operation of Aneurysmal Subarachnoid Hemorrhage

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.

Inclusion Criteria:

• Patients with acute subarachnoid hemorrhage
• Patients who underwent frontal-temporal craniotomy pterional approach aneurysm clipping surgery under general anesthesia.
• Patients operated by the same surgeon (Dr. Chen Xiaolin).

Exclusion Criteria:

• Patients who do not agree to the surgery.
• Patients who have congestive heart failure and kidney insufficiency.
• Patients who have pre-operative electrolyte imbalance.
• Patients who did not take the frontotemporal pterygoid approach.
• Patients with contraindications to mannitol due to low blood pressure.
• Patients who have had more than 3 days from bleeding to surgery.
• Patients with intracranial hematoma.
• Patients with Hunt-Hess grades 4-5.
• Patients who received intravenous mannitol within 6 hours before surgery.
• Patients who underwent ventricle puncture and drainage surgery before surgery.