Spinal Anesthesia For Enhanced Recovery After Liver Surgery

Inclusion Criteria: * Male or female, Adults aged ≥ 18 years (there will be no upper age restriction); * American Society of Anesthesiologists Physical Status classification (ASA-PS) of I to III; * Undergoing subcostal or midline laparotomy for elective liver resection surgery under general anesthesia; if the planned procedure is a combined operation (i.e., concomitant extrahepatic surgery) , the associated procedure should not add more than one hour to the surgical time of the primary hepatic resection procedure alone; * Stated willingness to comply with all study procedures and availability for the duration of the study * Provision of signed and dated informed consent form * Body mass index (BMI) between 17 and 40 kg·m-², inclusive; * Negative result on serum pregnancy test at Screening and negative urine pregnancy test at Baseline (for women of childbearing potential, defined as those who have not undergone a hysterectomy or been postmenopausal for at least 12 consecutive months); and not currently breastfeeding, or planning to do so within 7 d following surgery; * Stated willingness and ability to comply with all study and/or follow-up evaluations and communicate clearly with the Investigator and staff; and * Voluntary participation and ability to provide written informed consent prior to any study procedures. Exclusion Criteria: * Emergency surgery; * Age \< 18 years; * Planned laparoscopic hepatic resection; * Planned laparotomy incision other than (right) subcostal, midline, or extended midline; * Patients with obvious non-resectable disease prior to signing informed consent; * Liver transplant recipient or previous hepatic resection or living-donor hepatectomy surgery; * Major surgery (open abdominal and/or thoracic) under general anesthesia ≤ 30 d preoperatively; * Contraindications to neuraxial (spinal or epidural) anesthesia: (a) anticipated difficult intubation; (b) coagulation or hemostatic abnormalities within 30 d of surgery (defined as thrombocytopenia \[platelet count \< 100 × 10⁹ L-¹\]; INR \> 1.4; or activated partial thromboplastin time \[aPTT\] \> 40 s); (c) bleeding diathesis; (d) ongoing use (≤ 7 d before surgery) or planned perioperative use of antiplatelet agents (apart from acetylsalicylic acid 81 mg) or anticoagulants (excluding deep-vein thrombosis prophylaxis); (e) recent (≤ 30 d preoperatively) systemic infection or current (≤ 48 h) fever (≥ 38.4 °C), or evidence of infection (including superficial cutaneous infection in the thoracic and/or lumbar regions); (f) history of neurologic disorder affecting the spinal cord or the hemithorax or below; or impaired bladder/bowel function; (g) acute or subacute (≤ 90 d preoperatively) intracranial hemorrhage; or (h) technical contraindications to epidural placement: (i) local skin or soft tissue infection at proposed site for thoracic epidural insertion; (ii) previous cervicothoracic, thoracic, or thoracolumbar spinal surgery; (iii) history of spinal tumor, fracture or infection; or (iv) recent (≤ 14 d preoperatively) epidural corticosteroid injection; * Significant cardiac arrhythmias (including pacemaker-dependence) or clinically significant cardiovascular disease (New York Heart Association \[NYHA\] functional classification III-IV); * Volume overload (hyperhydration), particularly in cases of pulmonary edema or acute decompensated congestive heart failure (CHF); * Acute kidney injury (AKI) and/or chronic kidney disease (CKD) based on the 2012 Kidney Disease Improving Global Outcomes (KDIGO) AKI (excluding the oliguria criterion) and CKD guideline definitions: AKI: increase in serum creatinine (SCr) (≥ 26.5 μmol·L-¹ within 48 h or ≥ 1.5× baseline within 7 d); CKD: abnormalities of kidney structure or function, present for \> 3 mo, defined as either of the following present for \> 3 mo: (1) ≥ 1 marker(s) of kidney damage: (a) albuminuria (24-h albumin-creatinine ratio \[ACR\] ≥ 30 mg·g-¹ \[≥ 3 mg·mmol-¹\]), (b) urine sediment abnormalities, (c) electrolyte and other abnormalities due to tubular disorders, (d) abnormalities detected by histology, (e) structural abnormalities detected by imaging, (f) history of kidney transplantation; and/or decreased glomerular filtration rate (GFR \< 60 mL-¹·min-¹·1.73 m-², estimated using the 2009 CKD-EPI creatinine equation \[eGFR\_creat\]); * Severe hypernatremia (\[Na⁺\] ≥ 155 mmol·L-¹) and/or hyperchloremia (\[Cl-\] ≥ 125 mmol·L-¹); * Chronic pain; current (≤ 30 d preoperatively) and/or prior chronic (for a period of ≥ 90 d) opioid use; or history of alcohol, opiate, and/or other drug abuse or dependence; * Use of supraphysiologic glucocorticoid (GC) doses (≥ 7.5 mg·day-¹ of prednisone or equivalent): recent (≤ 30 d), prolonged (\> 2 consecutive weeks), or multiple courses totalling \> 3 weeks in the preceding 6 months; * Known allergy or sensitivity (e.g., glucose-6-phosphate dehydrogenase \[G6PD\] deficiency) to amide local anesthetics, opioids, or acetaminophen, or hypersensitivity to other materials to be used in the study (e.g., latex \[epidural catheter adapter\], epidural dressing or tape); or * Altered mental status or educational, psychiatric, or communication (language, literacy) barriers that would impede accurate assessment of postoperative pain and/or ability to complete questionnaire instruments.