Remimazolam has shown promising results for sedation in colonoscopy . Alfentanil is widely used in the analgesia of ERCP . The purpose of the study was to determine the 90% Effective Dose of Remimazolam for Duodenoscopy Insertion During ERCP With Alfentanil 10µg/kg

1. Title:The 90% Effective Dose of Remimazolam for Duodenoscopy Insertion During ERCP With Alfentanil 10µg/kg 2. Research center: Single center. 3. The population of the study: Age is between 18 and 85 years; ASA I-III levels; Patients undergone elective ERCP surgery, non-intubation patients; 4. Sample size:The sample size was decided based on that of prior Literature.The study was carried out using a biased coin design up-and-down sequential method, where the dose of remimazolam administered to each patient depended on the response of the previous one with success/failure duodenoscopy insertion during ERCP are required for reliable estimates. The first patient recruited received a dose of 0.2mg/kg, based on our past experience.Subsequently, if a patient had a failure duodenoscopy insertion, the dose of remimazolam was increased by 0.025mg/kg in the next subject. If a patient had a successful duodenoscopy insertion the next subject was randomised to receive either a lower dose (with a decrement of 0.025mg/kg), with a probability of b = 0.11, or the same dose, with a probability of 1-b = 0.89.

We defined duodenoscopy insertion a failure was as gross purposeful muscular movement, coughing or vomiting occurring during or within 2 minutes of insertion of duodenoscopy. If BIS>75 and MOAA/S > 1 when 3 min after the intravenous injection of remimazolam, it was considered a failure, and the patient received rescue sedation. Success was depicted when the reactions mentioned earlier were absent.

Inclusion Criteria:

• Age is between 18 and 85 years
• ASA I-III levels;
• Patients undergone elective ERCP surgery, non-intubation patients;

Exclusion Criteria:

• Chronic pain with long-term use of analgesics, psychotropic substances (including opioids, NSAIDs, sedatives, antidepressants), alcohol abusers, with known drug allergy;
• BMI<18 or BMI>30;
• Previous abnormal surgical anesthesia recovery history;
• Hypertension or systolic blood pressure greater than 160 mmHg or diastolic blood pressure greater than 95 mmHg when the patient admission to the operating room
• Suffering from esophageal reflux; • Sedatives, analgesics and antipruritic drugs were used 24 hours before operation;
• Expected difficult intubation ;
• Opioids allergy history;
• Take monoamine oxidase inhibitor or antidepressant within 15 days;
• Pregnant or parturient women;
• Involved in other drug trials within three months;
• Patients who can not communicate well with the researcher