With more and more people developing hypertension and atherosclerosis, the morbidity rate of Acute Aortic Dissection（AAD） has been increasing. Emergency surgery is the main treatment for Acute Aortic Dissection. However the secondary injury caused by reperfusion of spinal cord could lead to Catastrophic complications,such as paraplegia, hemiplegia or even death. So spinal protection is always the hot topic in clinical research.

Xenon is an ideal anesthetic gases with the following features,fast onset of action, stable hemodynamics, clean and non-toxic.The animal researches have showed the protective effects of xenon to alleviate the ischemia-reperfusion injury of the nervous system.Those clues suggest that Xenon may have the potential protection of spinal cord in patients undergoing aortic dissection repair.In order to clarify this hypothesis, the investigators designed this randomized, controlled clinic trial to evaluate the protection of Xenon against spinal cord ischemia-reperfusion injury and the potential mechanisms

Inclusion Criteria:

• Patients doing selective operation of Bentall and Sun's or partial aortic arch replacement
• Patients doing selective operation of the full chest and abdominal aorta replacement

Exclusion Criteria:

• Emergency patient
• Patients with severe mental and neurological dysfunction
• Patients with severe hearing and visual impairment
• Illiteracy or patients can't cooperate with doing the cognitive function score
• Patients with severe cardiac insufficiency
• critically ill or dying patients
• Patients refuse to sign the informed consent