A 2×2 Factorial Randomized Controlled Trial for ERCP

Inclusion Criteria: * Age ≥ 60 years old. * ASA II-III level. * BMI\<30kg/m2. * Patients who require elective therapeutic ERCP. * Voluntarily participate in this study and sign an informed consent form. If the subject is unable to read and sign the informed consent form due to reasons such as lack of capacity, their guardian needs to act as a proxy for the informed process and sign the informed consent form. If the subject lacks the ability to read the informed consent form (such as illiterate subjects), a witness is required to witness the informed process and sign the informed consent form. Exclusion Criteria: * Previous anatomical changes in the gastrointestinal tract, delayed gastric emptying, and gastric outlet obstruction. * Coagulation dysfunction or tendency towards nosebleeds. * Combined severe heart disease (coronary heart disease, myocardial infarction, congestive heart failure, left ventricular ejection fraction\<40%, tachyarrhythmia) * Have a history of allergies to relevant anesthetic drugs in the past. * Severe pulmonary diseases (severe asthma attacks, respiratory failure, severe chronic obstructive pulmonary disease, severe interstitial lung disease, large pleural effusion, severe pulmonary arterial hypertension, etc.). * Existing upper respiratory tract infection (within one week). * Uncontrolled severe hypertension. * Patients with increased intracranial pressure; Cerebral hemorrhage, intracranial space occupying lesions, acute phase of traumatic brain i…