Erector Spinae Plane Block With Ropivacaine for Major Upper Abdominal Surgery

Inclusion Criteria: 1. Adults who are scheduled to undergo major upper abdominal surgery (e.g. Pancreato-duodenal resection). If enrollment rates are insufficient, patients undergoing other major upper abdominal surgery will be enrolled (e.g in the supraumbilical area: liver resection, colon resection; Whipple procedure; gastrectomy). 2. Males or females 18-70 years of age 3. American Society of Anesthesiologists physical status class I,II, III 4. Signed informed consent Exclusion Criteria: 1. Patients undergoing emergency surgery 2. Decompensated cardiovascular disease (e.g. left ventricular ejection fraction ≤40%), chronic heart failure, rhythm and conduction disorders, coagulopathies) 3. Comorbid obesity (BMI≥35kg/m2) 4. Anomalies of vertebral column 5. Use of anticoagulants and patients with hypocoagulable conditions 6. Pregnancy 7. Physician preference for therapeutic anticoagulation 8. Infection of skin at site of needle puncture 9. Known allergies to study drugs