Inclusion Criteria:  Patients with asAI-III indications for painless gastroenteroscopy and receiving diagnostic or therapeutic gastroenteroscopy; Aged 60-75, body mass index (BMI) 19-28 kg/m2, Systolic blood pressure of 90-140mmHg, diastolic blood pressure of 50-90mmHg, resting heart rate of 50-100bpm and blood pulse oxygen saturation ≥95%  Exclusion Criteria:  Those who are refused to be included; Those who are allergic to the drugs used in this study; Epilepsy and other mental illnesses, a history of addiction such as opiates and other analgesics and/or tranquilizers (hypnotics); Severe cardiac dysfunction: NYHA cardiac functions grade 3-4, a history of recent myocardial infarction or cerebral infarction, severe conduction block or malignant arrhythmia; Renal failure or liver cirrhosis; Severe lung infection or upper respiratory tract infection; Sleep apnea syndrome, difficult airway (Mallampati score of 3 or 4) or asthma status; Advanced cancer accompanied by extensive intra-abdominal metastasis, acute and chronic obstruction of the gastrointestinal tract, bleeding and severe abdominal effusion; -