TAES Improve the Function of Respiration and Circulation on Elderly Patients Undergoing Colonoscopy Procedure

Inclusion Criteria: 1. patients aged 65 or older 2. American Society of Anesthesiologists (ASA) grade I\~II 3. consent and voluntary participation in this experiment 4. patients under colonoscopy 5. none allergic to propofol and fentanyl 6. airway assessment for none difficult airway Exclusion Criteria: 1. Allergic to propofol, fentanyl. 2. ASA is greater than or equal to grade 3 3. Abnormal respiratory tract may cause severe respiratory obstruction 4. unsatisfactory control of hypertension, systolic pressure over 160 millimeter of mercury (mmHg) or diastolic pressure over 100 mmHg 5. Hypotension, systolic pressure below 90 mmHg, heart rate (HR) \<50bpm or \>100bpm