Surgical pain refers to pain that occurs immediately after surgery, including physical pain and visceral pain. Appropriate perioperative analgesia is a fundamental component of enhanced recovery after surgery. Especially, 45% of postoperative patients experience inadequate pain after gastrointestinal surgery, and uncontrolled postoperative pain prompts respiratory distress, delays wound healing, and a potentially eventual transition from acute to chronic pain problems. Thus, it severely challenges the proper use of analgesics for patients undergoing laparoscope gastrointestinal surgery to clinicians.~Sufentanil is one of the most common opioid used in patient-controlled analgesia (PCA), it may induce many adverse events including respiratory depression, nausea, vomiting, constipation, urinary retention, pruritus, and drowsiness. Many drugs have been combined with dexmedetomidine in PCA to augment analgesic effect or to reduce the adverse events.~Nalbuphine is a mixed agonist-antagonist opioid. Nalbuphine derives its analgesic and sleep-producing effects through agonism at the kappa-opioid receptor with fewer opioid-induced adverse effects. some articles show that it also has the potential to attenuate the mu-opioid receptor-related adverse events. The investigators hypothesized that the clinical effect of nalbuphine in combination with dexmedetomidine might be different from that of sufentanil in combination with dexmedetomidine. Unfortunately, the optimal dosing of nalbuphine combined with dexmedetomidine for the PCIA after the laparoscopic gastrointestinal surgery, has not been determined.~So, the investigators performed a nalbuphine and dexmedetomidine dose finding study, for the PCIA after the laparoscopic gastrointestinal surgery, to establish their 95% effective dose (ED95). The investigators then compared the clinical effect and adverse events of the newly established dosing regimen of nalbuphine combined with dexmedetomidine, to the equivalent dosing of sufentanil combined with dexmedetomidine, in the same patient population.
Surgical pain refers to pain that occurs immediately after surgery, including physical pain and visceral pain. Thus, it severely challenges the proper use of analgesics for patients undergoing laparoscope gastrointestinal surgery to clinicians.~Nalbuphine is a mixed agonist-antagonist opioid. The investigators hypothesized that the clinical effect of nalbuphine in combination with dexmedetomidine might be different from that of sufentanil in combination with dexmedetomidine.~So, the investigators performed a nalbuphine and dexmedetomidine dose finding study, for the patient controlled anaesthesia (PCA) after the laparoscopic gastrointestinal surgery, to establish their 95% effective dose (ED95). The investigators then compared the clinical effect and adverse events of the newly established dosing regimen of nalbuphine combined with dexmedetomidine, to the equivalent dosing of sufentanil combined with dexmedetomidine, in the same patient population.