Hyperosmotic agents are used to decrease intracranial pressure. The aim of the study is to compare the effects of continuous 3% hypertonic saline (HS), bolus HS and 20% mannitol on intraoperative brain relaxation in patients with raised intracranial pressure during surgery for supratentorial tumors.

After obtaining approval from the ethics committee and informed consent, a total of 90 patients aged 18-70 years, conscious (GCS>13) and American Society of Anesthesiologists (ASA) class I-III, who had intracranial shift >0.5 cm or glioblastoma multiforme or metastatic tumor and who were scheduled for supratentorial mass resection under elective conditions, will be included in the present prospective, randomized, double-blind and placebo-controlled study. Patients with heart failure, kidney insufficiency, diabetes insipidus, electrolyte imbalance and who are unconscious will be excluded from the study.

The patients will randomized into 3 groups:

Group 1: %3 HS bolus 3 mL.kg-1 Group 2: %3 HS infusion 20 ml/h Group 3: %20 mannitol 0,6 gr.kg-1 After head fixation, all patients will be administered with HS or mannitol (over 20 minutes). Arterial blood gas (ABG) analysis (Cobas b 221 blood gas analyzer, Roche®, Basel, Switzerland) will be made at 30 minute,2,4,6,8. hours. Blood sodium, potassium, chlorine, base excess, lactate levels and blood osmolarity will be recorded in each time intervals. The brain relaxation scale will be recorded at the time of dura opening.

Inclusion Criteria:

• Elective supratentorial tumor resection
• Glioblastoma multiforme
• Metastatic tumor
• Intracranial shift >0.5 cm
• GCS>13

Exclusion Criteria:

• Renal failure
• Heart failure
• Electrolyte imbalance

All the patients, the anesthesiologist who will evaluate the postoperative cranial CT will be blind to study group