Dexmedetomidine as an Adjuvant to Bupivacaine for Ultrasound-Guided External Oblique Intercostal Block

Inclusion Criteria: * Patients aged 18-70 years scheduled for elective upper abdominal cancer surgery (e.g., gastrectomy, hepatectomy, pancreatectomy). * American Society of Anesthesiologists (ASA) physical status I-III. * Body mass index (BMI) between 18-35 kg/m². Exclusion Criteria: * Patient refusal. * Allergy to local anesthetics or dexmedetomidine. * Coagulopathy (INR \>1.5, platelet count \<100,000/mm³). * Infection at the injection site. * Severe cardiopulmonary, renal, or hepatic dysfunction. * Chronic opioid use (\>30 mg morphine equivalents daily for \>3 months). * Pregnancy or lactation.