Postoperative Analgesia in Patients Undergoing Open Upper Abdominal Surgeries: External Oblique Intercostal Plane Block vs. Quadratus Lumborum Block

Inclusion Criteria: * Patients from both sexes. * 18 to 60 years old. * ASA physical status I- III scheduled for elective open upper abdominal surgeries, as (open nephrectomy, open cholecystectomy, liver resection, ….). * Patients with BMI (18.5-35) kg/ m2. Exclusion Criteria: * Patients uncooperative or refuse to sign the consent of regional block. * Patients with known coagulation defects. International normalized ratio (INR)\> 1.5), and thrombocytopenia if platelet count \< 100.000). * Patients with known hypersensitivity to bupivacaine, or any of the used drugs. * Patients with hepatic impairment, as Child-Pugh class B or C, AST/ALT \> 3 times the upper limit of normal, or total bilirubin \> 2 mg/dL. * Patients with renal impairment, chronic kidney disease stage 4 or 5 (eGFR \< 30 mL/min/1.73 m²), or on regular dialysis. * Patients with pre-existing myopathy, defined as a clinically diagnosed muscular disorder characterized by muscle weakness, elevated creatine kinase levels, or a history of inherited or acquired muscle disease (e.g., polymyositis, muscular dystrophy). * Patients with pre-existing neuropathy, if clinically diagnosed as peripheral or central nerve dysfunction, including chronic sensorimotor deficits or conditions such as diabetic neuropathy, radiculopathy, or multiple sclerosis. * Patients with chronic pain syndromes, defined as pain persisting for more than 3 months, including fibromyalgia, complex regional pain syndrome (CRPS), or chronic pain requiri…