Pulse pressure variation (PPV) to standard fluid management (4ml/Kg/hr) in patients undergoing supratentorial mass excision. The investigators hypothesize that in these procedures, goal-directed fluid therapy (GDT) might improve brain relaxation, and patient hemodynamics intra and postoperatively.

Neurosurgical operations are characterized by major fluid shift, frequent use of diuretics, and prolonged operative time. The role of fluid therapy in these patients is very critical, hypovolemia might lead to brain hypoperfusion and over-transfusion might lead increased intracranial tension. All these factors make fluid management in these procedures complex and challenging. Evidence on the optimum protocol for intraoperative fluid management in neurosurgical patients is still lacking.

Goal-directed therapy (GDT) in the operating room is a term used to describe the use of cardiac output or similar parameters to guide intravenous fluid and inotropic therapy.

Although GDT was well reported in many procedures, its benefit in neurosurgical operations is not well studied.

Pulse pressure variation (PPV) is a famous dynamic method of fluid responsiveness. PPV is simply calculated by dividing the largest pulse pressure (PPmax - PPmin) by the average pulse pressure (PPmax + PPmin /2) and expressed as percentage. PPV was previously used in GDT in major abdominal surgery with good performance.

The aim of this study is to compare the restricted fluid approach (1 ml/Kg/hr) guided by PPV to standard fluid management (4ml/Kg/hr) in patients undergoing supratentorial mass excision. The investigators hypothesize that in these procedures GDT might improve brain relaxation, and patient hemodynamics intra and postoperatively.

Inclusion Criteria:

• Patients scheduled for supratentorial mass excision will be enrolled in the study.

Exclusion Criteria:

• Patients with arrhythmias, pulmonary hypertension, impaired cardiac contractility, impaired liver or kidney function, and patients with BMI above 40 will be excluded.