Fluid management during neurosurgery presents a special clinical agenda. Volume overload can have detrimental effects on intracranial pressure by increasing either cerebral blood volume or hydrostatically driven cerebral edema formation. On the other hand, an overt restrictive fluid strategy may risk hemodynamic instability.

Recently, dynamic fluid responsiveness parameters such as stroke volume variation (SVV) have been shown as a more precise parameters for fluid management including in neurosurgical patients. The threshold of SVV is reported about 10-15%. In this study, the investigators aim to using two SVV threshold to conduct intraoperative fluid therapy for craniotomy. Randomization will be generated by computer sampling. One of the two groups of patients will be managed with fluid bolus to keep intraoperative SVV <10% presenting the "normovolemia" group. The other group of patients will be kept intraoperative SVV <18% which is slightly above previously reported SVV threshold upper limit. The second group thus presents the "restrictive" group. Clinical outcomes, laboratory analysis including S100-B for neuronal damage and neutrophil gelatinase-associated lipocalin (NGAL) for acute kidney injury, will be compared.

Inclusion Criteria:

• Supratentorial brain tumor receiving elective craniotomy
• BMI between 18.5-27.0 kg.m-2

Exclusion Criteria:

• Cardiac dysfunction, such as coronary artery diseases; atrial fibrillation;

  • NYHA class II

• Renal dysfunction, eGFR< 60 ml.min-1.1.73m-2

• Pulmonary cormorbidity, such as COPD