Objective To evaluate the effect of patient-controlled intravenous analgesia combined with different opioid receptors for gastrointestinal surgery. Methods A total of 4342 patients who underwent gastrointestinal postoperative analgesia in the first affiliated Hospital of Air Force military Medical University from May 2018 to March 2022 were collected retrospectively. The patient-controlled intravenous analgesia regimen in this study was composed of different opioid receptor drugs：sufentanil combined with nalbuphine group (SN group) and Hydromorphone combined with nalbuphine group (HN group) and single opioid receptor group: sufentanil group (S group). SN group ,HN group and S group were treated with sufentanil 100 μ g + nalbuphine 40 mg, hydromorphone 10 mg+ nalbuphine 40 mg, sufentanil 200 μ g, diluted to 100 ml, background dose 1 ml/h, PCA dose 0.5 ml, locking time 10 min. The demographic data of the three groups were collected, the number of patients with insufficient static and dynamic analgesia (VAS ≥ 4) at 24 and 48 hours after operation, the adverse reactions at 24 and 48 hours after operation, the first exhaust time and the first ambulation time were collected, evaluate the analgesic effect of combination of different opioid receptor drugs and single opioid receptor drugs in PCIA after gastrointestinal surgery.

Control group：S group Test group：SN group and HN group Observation index：the number of patients with insufficient static and dynamic analgesia (VAS ≥ 4) at 24 and 48 hours after operation, the adverse reactions（drowsiness, nausea and vomiting, respiratory depression, dizziness） at 24 and 48 hours after operation, the first exhaust time and the first ambulation time were collected

Inclusion Criteria:

• 18-75 years ,there is no gender limit，ASA grade Ⅰ-Ⅱ

Exclusion Criteria:

• BMI > 35 kg/m2, history of upper abdominal surgery, history of analgesic or hormone use before operation, history of depression or chronic pain before operation, infection before operation and ICU after operation