The primary goal of anesthesia is the maintenance of physiologic homeostasis. This includes monitoring and treatment of cardiovascular, pulmonary, neurologic and kidney functions changes during the perioperative period to minimize adverse outcomes. Optimizing intraoperative physiology may help speed recovery and provide for perioperative organ system protection. Knowledge of the influence of anesthetics on cerebral blood flow and metabolism is important for safe anesthesia practice.The potent halogenated inhalation anesthetics are all dosedependent cerebral vasodilators. While they reduce cerebral metabolic rate (CMR), they can blunt cerebral autoregulation by uncoupling cerebral blood flow (CBF) and metabolism and subsequently increase CBF. However, total uncoupling of the CBF and metabolism does not happen. Cerebral autoregulation is dose-dependently altered. Brain metabolism decreases which causes a decrease in CBF. That is counteracted by the direct vasodilatation of brain blood vessels by volatile anesthetics. Maintaining adequate ICP levels is crucial for neurosurgical patients. The degree to which the potent halogenated inhalation agents increase CBF and therefore intracranial pressure (ICP) depends on sum of the mediated vasoconstriction and the direct vasodilatation . Nitrous oxide gas increases cerebral metabolism and cerebral blood flow. Xenon increases cerebral blood flow as well.