Effects of Dexmedetomidine on Postoperative Cognitive Dysfunction During One-lung Ventilation in Elder Patients

Exclusion Criteria

• •Systolic blood pressure more than 180 mmHg or lower than 90 mmHg,diastolic blood pressure more than 110 mmHg or lower than 60 mmHg.
• •Serious heart,liver,kidney, pulmonary, and endocrine disease or serious infection.
• •Suspected or confirmed difficult airway.
• •History of abnormal anesthesia.
• •Suspected of malignant hyperthermia.
• •Use of sedative and antidepressant drug or serious alcoholism
• •Mini-mental State Examination less than 17.
• •Highest academic degree below grade 6 in primary schools
• •Patients inability to exchange with serious visual and hearing impairment or mental disability.
• •History of shock.
• •Carotid artery stenosis and central nervous system disease such as stroke, epilepsy.
• •Allergic to investigational products or with other contraindication.
• •Participated in other study within 30 days .