Comparative Study Between the Efficacy of The Serratus Anterior Plane Block and Lumbar Intrathecal Fentanyl Injection for Postoperative Analgesia After Modified Radical Mastectomy

SAPB will be done preoperative before induction of anesthesia under songraphic guidance and aseptic conditions with the patient in the lateral position, with the side of the surgical side up and the upper limb hanging over the patient's head. The ribs will be then counted, and when the 5th rib is identified, the high-frequency probe will be put over it, in the mid-axillary line in a sagittal plane. The ribs, pleura, overlying serratus muscle and latissimus dorsi muscle will be identified, and the needle will be advanced cephalic in-plane until the tip reaches the plane between the serratus anterior and latissimus dorsi. Afterward, 2 mL dextrose 5% will be injected; then, 30 mL of bupivacaine 0.25% will be injected in the plane between the serratus anterior and latissimus dorsi.

Patients will receive 25 microgram intracthecal fentanyl immediately preoperative.