We aim to evaluate the change in optic nerve sheath diameters as a surrogate of intracranial pressure before and after mannitol administration in patients who undergo robot assisted laparoscopic radical prostatectomy with pneumoperitoneum and Trendelenburg position.

Mannitol has been frequently used for renal protection during surgery. Optic nerve sheath diameter is used to evaluate intracranial pressure noninvasively. Robot-assisted laparoscopic radical prostatectomy can induce an increase in optic nerve sheath diameter due to Trendelenburg position and carbon dioxide insufflation. We therefore aim to evaluate the change in optic nerve sheath diameters before and after mannitol administration in patients who undergo robot assisted laparoscopic radical prostatectomy.

Inclusion Criteria:

• prostate cancer patients undergoing robot assisted laparoscopic radical prostatectomy.
• 20 year old or above, 79 year old or below.
• agreed to participate this study.

Exclusion Criteria:

• history of cerebrovascular accident.
• history of congestive heart failure.
• history of pulmonary edema.
• history of anaphylaxis to mannitol.
• conversion to open prostatectomy.
• combined with other operation.
• inability to measure optic nerve sheath diameter.

Only male included.

Prostate cancer patients who undergo Robot-assisted laparoscopic radical prostatectomy.