Inclusion Criteria:  60 years old; There is no limit on the gender, ASA (American Society of Anesthesiologists )Ⅰ-Ⅲ  Exclusion Criteria:  Emergency surgery, severe hepatic and renal dysfunction, shock or coma, psychiatric disease or central nervous system disorder or a history of long-term use of psychiatric medications, cognitive dysfunction, severe arrhythmia or bradycardia, ketamine allergy,drug abuse history and used other sedatives for nearly a week