Afentanil and Remifentanil for Anesthesia Quality and Recovery

The goal of this clinical trial is to compare two commonly used opioid pain medications-alfentanil and remifentanil-during general anesthesia for surgery, and to find out whether alfentanil is as good as (not worse than) remifentanil in keeping patients stable (steady blood pressure and heart rate) and adequately pain-free during the operation. The study will enroll adults aged 18-65 years who are in good to fair health (ASA class I-III) and are scheduled for elective non-cardiac, non-brain surgery lasting 1 to 4 hours with expected blood loss under 500 mL. The main questions it aims to answer are: How often do patients need extra painkillers or blood-pressure medications during surgery (a "rescue event") when receiving alfentanil compared with remifentanil? How quickly do patients wake up, breathe on their own, and get discharged from the recovery room after the operation? Do patients experience differences in pain levels, nausea, vomiting, or thinking/memory problems in the days after surgery? If there is a comparison group: Researchers will compare the alfentanil group with the remifentanil group to see if the rate of rescue events with alfentanil is not more than 8% higher than with remifentanil (the non-inferiority margin). Both groups will receive the same standard anesthetic (propofol and muscle relaxants) and the same postoperative pain management; only the study opioid differs. Participants will: Sign an informed consent form and undergo screening tests, including blood work, physical exam, and medical history review. Be randomly assigned (like a coin flip) to receive either alfentanil or remifentanil during their operation, with the drug given through an IV. Neither the patient nor the care team will know which drug is given until after the study is completed. Have their blood pressure, heart rate, breathing, and brain activity (using BIS monitors to measure depth of anesthesia) continuously tracked during surgery. After surgery, be followed for up to 3 days, during which they will be asked to rate their pain (using a simple 0-10 scale) and complete a short memory/thinking test (MMSE) at set times. Provide small blood samples before, right after, and 24 hours after surgery to measure stress hormones and inflammation markers. This study will involve about 990 patients across multiple hospitals and will take about 2 years to complete. The results will help doctors choose the best opioid for safer, smoother surgeries and faster recovery.

Inclusion Criteria:(1) Age between 18 and 65 years, with no gender restriction; (2) BMI ≥ 18 kg/m²; (3) ASA classification I-III; (4) Elective surgeries that are not related to the chest or brain, with an anticipated duration of 60-240 minutes; (5) Anticipated blood loss \< 500 mL; (6) Voluntary consent to sign the Informed Consent Form. Exclusion Criteria:(1) Abuse or long-term use of opioid medications; (2) Severe hepatic and renal dysfunction (ALT/AST \> 2×ULN, Cr \> 176 μmol/L); (3) Serious cardiovascular diseases, including but not limited to: Severe cardiac arrhythmias or conduction abnormalities, such as ventricular arrhythmias requiring clinical intervention, second- or third-degree atrioventricular block, or uncontrolled atrial fibrillation; a history of acute myocardial infarction, unstable angina pectoris within the past 6 months, or having undergone coronary stenting or coronary artery bypass surgery. Congestive heart failure classified as NYHA Class II or above, or left ventricular ejection fraction (LVEF) \< 50%. (4) A history of cerebrovascular accidents (including ischemic and hemorrhagic strokes) or transient ischemic attacks within the past 6 months; (5) Uncontrolled severe hypertension: resting systolic blood pressure ≥ 160 mmHg and/or diastolic blood pressure ≥ 100 mmHg (confirmed by repeated measurements); (6) Symptomatic aortic dissection, or lower limb arterial occlusion requiring treatment.(4) Severe blood system disorders, including but not limited to severe anemia, aplastic anemia, acute leukemia, thrombotic thrombocytopenic purpura, etc. (5) Difficulty in predicting airway management; (6) Pregnancy or lactation; (7) Allergy to opioids/propropofol/eggs/soybeans; (8) Participation in other clinical trials within the past 3 months. \-