Postoperative cognitive decline (POCD) is a common and impactful outcome of surgical procedures in older adults. The pathophysiology and causative mechanisms for POCD are poorly understood. The robot-assisted radical cystectomy (RARC) is increasingly utilized. In patients undergoing RARC, Although prolonged Trendelenburg position and pneumoperitoneum can increase the cerebral blood flow, the excessive cerebral perfusion can lead to encephalemia, which reduce the oxygen uptake of brain tissue and cause insufficient oxygenation of brain tissue at the cellular level. POCD may take place due to cerebral hemodynamic changes. The goal of the current study is to investigate the combined effect of this position and CO2 pneumoperitoneum on POCD during RARC with the monitor of cerebral oxygen.

Postoperative cognitive decline (POCD) is a short-term decline in cognitive function (especially in memory and executive functions) that may last from a few days to a few weeks after surgery. It is a common and impactful outcome of surgical procedures in older adults. The pathophysiology and causative mechanisms for POCD are poorly understood. It is supposed to be associated with numerous factors such as ages, trauma, inflammation, surgical stress, position, fluid, MBP, artificial pneumoperitoneum , PCO2, FiO2.

The robot-assisted radical cystectomy (RARC) is increasingly utilized. In patients undergoing RARC, Although prolonged Trendelenburg position and pneumoperitoneum can increase the cerebral blood flow, there were studies showed that the excessive cerebral perfusion can lead to encephalemia, which reduce the oxygen uptake of brain tissue and cause insufficient oxygenation of brain tissue at the cellular level. POCD may take place due to cerebral hemodynamic changes. Contemporary, intraoperative fluid restriction, a relatively long time of operation and surgical stress may also contribute to POCD.

The goal of the current study is to investigate the combined effect of this position and CO2 pneumoperitoneum on POCD during RARC with the monitor of cerebral oxygen.

Inclusion Criteria:

• Above age of 55
• Will undergo the robot-assisted radical cystectomy
• informed consent, volunteered to participate in this experiment, ASA I - III

Exclusion Criteria:

• Audio and visual impairment, illiteracy
• Existing severe central nervous system disease
• Patients with central nervous system disease or surgery , resulted in severe sequelae
• Alcohol dependence
• Take psychotropic medications
• Preoperative MMSE score was less than 24

Chinese

The study choose Chinese patients(ASA I - III

) above the age of 55, who will recently undergo the robot-assisted radical cystectomy. All those patients should be informed consent and be volunteered to participate in this experiment.

Those audio and visual impairment, illiteracy,existing severe central nervous system disease, patients with central nervous system disease or surgery which resulted in severe sequelae, alcohol dependence, usage of psychotropic medications, reoperative MMSE score was less than 24 should be excluded.