Efficacy and Safety of Adding Dexmedetomidine to Levobupivacaine in Rectus Sheath Block Compared to Quadratus Lumborum Block in Patients Undergoing Lower Abdominal Cancer Surgery: a Randomized Clinical Trial

40-ml mixture of 20 ml of 0.5% levobupivacaine diluted with 20 ml of 0.9% N.S. (20 ml to be injected on each side

60 ml mixture of 1.5 mic/kg dexmedetomidine added to 30 ml of 0.5% levobupivacaine diluted with 30 ml of 0.9% N.S. (30 ml to be administered on each side, divided into 15 ml for the upper segment and 15 ml for the lower segment).