This is a prospective randomized open-label noninferiority trial that compares intrathecal morphine injection and continuous wound infiltration after open pancreaticoduodenectomy.

Open pancreaticoduodenectomy causes severe postoperative pain due to the relatively large incision and tissue damage compared to other abdominal surgeries. Current Enhanced Recovery After Surgery (ERAS) guidelines recommend continuous wound infiltration for pancreaticoduodenectomy as an effective analgesic modality along with thoracic epidural analgesia. However, continuous wound infiltration is effective for somatic pain in the abdominal wall but not for visceral pain from the incision of internal organs. It also requires the placement of a catheter for several days after surgery, which can be inconvenient for patients.

Intrathecal morphine injection has been recommended as an effective analgesic method for abdominal surgery because they provide potent, long-lasting analgesia with a single injection and can provide equivalent analgesia with a much smaller dose compared to intravenous or oral morphine. Several previous studies have reported on the analgesic efficacy of a single intrathecal morphine injection including pancreaticoduodenectomy. However, no studies have compared a single intrathecal morphine injection with continuous wound infiltration for pancreaticoduodenectomy. To date, studies comparing the two methods of analgesia have only been reported in cesarean section and donor hepatectomy, and these studies either found no significant difference between the two methods of analgesia or reported that intrathecal morphine injection provided better analgesia in early postoperative period.

Therefore, the investigators will examine the effect of single intrathecal morphine injection for postoperative pain control in patients undergoing open pancreaticoduodenectomy to improve postoperative pain management and to explore its potential as one of the effective analgesic methods in ERAS protocol. To this end, the investigators will test non-inferiority between intrathecal morphine injection and continuous wound infiltration.

Inclusion Criteria:

• Adults 19 years of age or older
• Scheduled for elective open pancreaticoduodenectomy or pylorus preseriving pancreaticoduodenectomy
• Disease of periampullary lesions
• Perfromance status assessed with ECOG score is 0 or 1 at the time of enrollment
• Able to provide written informed consent to participate in the study, understand the procedures of this study, and complete patient-reported questionnaires
• American Society of Anesthesiologists physical status I to III

Exclusion Criteria:

• Hypersensitivity to medications used for pain control (fentanyl, ropivacaine, morphine, acetaminophen, NSAIDs)
• Cognitive impairment that affects using patient-controlled analgesia device or answering patient-reported questionnaires
• Infection or anatomical abnormalities of the abdominal wall and skin that preclude catheterization for continuous wound infiltration
• Contraindicated for intrathecal injection due to any coagulation disorder or continued use of anticoagulants
• Have a major medical or psychiatric illness that would affect response to treatment
• History of chronic pain, or chronic use of analgesics or psychiatric medications
• Have severe liver or kidney disease
• Anyone who are not appropriate for the study in the opinion of the investigators