Rhomboid Intercostal Sub-serratus Plane Block Versus External Oblique Intercostal Block in Open Nephrectomy

Inclusion Criteria: * Both sexes. * American Society of Anesthesiologists (ASA) physical status II, III. * Body mass index (BMI): \> 20 kg/ m2 and \< 35 kg/ m2. * Patients undergoing open nephrectomy. Exclusion Criteria: * Patient refusal. * BMI \<20 kg/m2 and \>35 kg/m2 * Known sensitivity or contraindication to drug used in the study (local anesthetics, opioids). * History of psychiatric and cognitive disorders or chronic pain. * Contraindication to regional anesthesia e.g pre- existing peripheral neuropathies. * Severe respiratory or cardiac disorders. * Advanced liver or kidney disease. * Pregnancy. * Physical status ASA IV. * Coagulopathy with INR ≥ 1.6: hereditary (e.g. hemophilia, fibrinogen abnormalities \& deficiency of factor II) - acquired (e.g. impaired liver functions with prothrombin concentration less than 60 %, vitamin K deficiency \& therapeutic anticoagulants drugs).