Ultrasound-Guided Modified Pectoral Plane (PECS II) Block Versus Erector Spinae Plane Block (ESPB) for Postoperative Analgesia of Modified Radical Mastectomy

The patient will lay supine with the ipsilateral arm abducted and externally rotated and the elbow flexed at 90 degrees. The probe will be placed transversely between the clavicle medially and above and the shoulder joint laterally. After identifying the pectoralis major and minor muscles and the plane between them, the probe will be pushed 1-2 cm caudally and medially. In a caudal tilt, within a biconvex space, the artery will be recognised. After that, the block needle will be inserted in an in-plane approach to the artery's location and 10 mL of 0.25% bupivacaine will be administered Then probe will be moved laterally and caudally towards the anterior axillary fold until the serratus muscle appears beneath the pectoralis minor muscle attaching to the underlying ribs. The needle will target the plane between pectoralis minor and serratus muscles at the level of the third rib, followed by negative aspiration into the fascial plane then injection of 10 mL of 0.25 bupivacaine.

The block will be performed with the patient in a sitting position , The high-frequency linear probe will be placed in a longitudinal orientation 3 cm from the midline. Once the erector spinae muscle and the transverse processes identified, the block needle will be inserted in a caudad-to-cephalad direction until the tip lay in the interfacial plane deep to the erector spinae muscle, 20 mL of 0.25% bupivacaine will be administered for block performance.