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.