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

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

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.

When the neurosurgeon starts the skin incision, 20% mannitol administered through the venous catheter with fulldrip in 5-10 minutes. Neurosurgeons evaluate the degree of brain relaxation after dura opening in 4 point scale (1=bulging brain, 2=firm brain, 3=satisfactorily relaxed, 4=perfectly relaxed).

The degree of brain relaxation after administration was assessed as four grades. denoting bulging or the condition that additional methods for brain relaxation are immediately and always required in order to continue the surgical procedure because of brain swelling; firm or the condition that additional methods for brain relaxation are occasionally required to continue the surgical procedure; adequate; perfectly relaxed. All patients received conventional frontotemporal pterional approach, and the time from skin incision to dural opening was constant for 30 minutes. At the time of dural opening, the degree of cerebral relaxation was evaluated, and the satisfactory cerebral relaxation was defined as 3 or 4 points.

Excessive decrease in intracranial pressure may lead to intraoperative or postoperative subdural hematoma formation

Poor intracranial pressure reduction may result in prolonged duration of surgery, and evaluation of the duration of surgery is helpful in the selection of the optimal dose.Poor intracranial pressure reduction may result in prolonged duration of surgery, and evaluation of the duration of surgery is helpful in the selection of the optimal dose.

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. Exclusion Criteria: Patients who does not agree to the surgery. Patients who have congestive heart failure and kidney insufficiency. Patients who have electrolyte imbalance.