Severe acute pancreatitis is a serious illness that can cause severe abdominal pain, inflammation, increased abdominal pressure, feeding intolerance, and early problems with breathing, circulation, and kidney function. Patients with severe acute pancreatitis often need treatment in the intensive care unit. Pain control is an important part of treatment, but conventional pain medicines, especially opioids, may cause side effects such as respiratory depression, reduced bowel movement, nausea, vomiting, delirium, and delayed enteral nutrition.

Thoracic epidural block is a regional pain-control technique. It may relieve abdominal pain by blocking pain signals and sympathetic nerve activity from the chest and upper abdominal region. This treatment may also reduce the need for systemic opioid medicines, improve bowel function, improve tolerance to enteral nutrition, and reduce the need for early organ support in some patients.

This study is a single-center, prospective, randomized, open-label, parallel-group trial. Adult patients with severe acute pancreatitis will be randomly assigned to either a thoracic epidural block group or a conventional analgesia group. Patients in the thoracic epidural block group will receive continuous thoracic epidural infusion of ropivacaine alone, without epidural opioids such as sufentanil, fentanyl, or morphine. Intravenous pain medicines will be used only before epidural block initiation, as rescue analgesia when epidural pain control is inadequate, or after epidural block is paused, fails, or is discontinued. Patients in the conventional analgesia group will receive standard pain treatment according to clinical practice.

The main goal of this study is to determine whether thoracic epidural block can increase the number of days patients are alive and free from ICU-level organ support during the first 14 days after randomization. ICU-level organ support includes invasive mechanical ventilation, noninvasive ventilation, vasoactive or inotropic drug infusion, and renal replacement therapy. The study will also evaluate pain scores, opioid consumption, enteral nutrition tolerance, intra-abdominal pressure, organ function scores, complications, length of ICU and hospital stay, hospital cost, 28-day mortality, and adverse events related to thoracic epidural block.

Inclusion Criteria:

1. Age 18 to 75 years.
2. Diagnosis of acute pancreatitis, defined by at least two of the following three criteria: typical acute upper abdominal pain; serum amylase and/or lipase greater than three times the upper limit of normal; imaging findings consistent with acute pancreatitis on contrast-enhanced CT, MRI, or ultrasound.
3. Admission or transfer to the study hospital within 72 hours after symptom onset.
4. Severe acute pancreatitis, or moderately severe acute pancreatitis with early respiratory, cardiovascular, or renal organ dysfunction.
5. Expected need for hospitalization and continuous clinical observation for at least 72 hours.
6. Written informed consent provided by the participant or legally authorized representative.

Exclusion Criteria:

1. Acute exacerbation of chronic pancreatitis.
2. Acute pancreatitis associated with pancreatic tumor.
3. Pregnancy or lactation.
4. Prior percutaneous abdominal drainage, retroperitoneal drainage, endoscopic drainage, necrosectomy, or surgery before randomization that may substantially affect outcome assessment.
5. End-stage malignant disease or expected survival less than 3 months.
6. Severe pre-existing cardiac, pulmonary, hepatic, renal, hematologic, immune, or neurological disease judged by investigators to interfere with outcome assessment.
7. Severe pre-existing neurological disease that prevents assessment of neurological complications.
8. Coagulopathy or bleeding risk judged to contraindicate epidural catheterization, including severe thrombocytopenia, elevated INR, prolonged APTT, or other clinically significant coagulation abnormality.
9. Ongoing anticoagulant or antiplatelet therapy for which discontinuation does not meet neuraxial anesthesia safety requirements.
10. Puncture site infection, epidural abscess, central nervous system infection, or uncontrolled severe systemic infection.
11. Severe spinal deformity, prior relevant spinal surgery, or anatomical abnormality that prevents safe thoracic epidural catheterization.
12. Intracranial hypertension, spinal cord disease, radiculopathy, or other central nervous system disorder that contraindicates neuraxial block.
13. Known allergy to local anesthetics or other study-related medications.
14. Refractory shock or severe hemodynamic instability not suitable for thoracic epidural block.
15. Severe psychiatric disease, cognitive impairment, or inability to cooperate with the study without availability of a legally authorized representative.
16. Participation in another interventional clinical trial within the previous 3 months.
17. Any other condition that, in the opinion of the investigators, makes the participant unsuitable for enrollment.

Deidentified individual participant data underlying the published results may be made available upon reasonable request after publication of the main study results. Data sharing will require approval by the principal investigator and the institution, and by the ethics committee when applicable. Data will be shared only for scientifically valid analyses and after signing an appropriate data use agreement.

Beginning 6 months after publication of the main study results and available for 3 years.

Qualified researchers may submit a written request including research purpose, analysis plan, requested data elements, and data protection measures. Requests will be reviewed by the principal investigator and the institution.

Due to the nature of thoracic epidural catheter placement and continuous epidural infusion, blinding of participants and treating clinicians is not feasible. The study will use an open-label design. The primary outcome will be calculated according to prespecified objective criteria based on ICU-level organ support. Statistical analysis will be performed according to a prespecified analysis plan.