U/S Guided Transversus Thoracic and Pectoral Nerve Block Versus Pectoral Nerve Block in MRM

The TTP block will be performed in a supine position before general anesthesia. First, a high linear probe of the ultrasound system will be attached at sagittal plane to the sternum and counted from T2 near the clavicle to T5. Then the linear probe will be rotated by 90° and attached between the forth and the fifth costal cartilages connecting at the sternum near nipple. Then, the transversus thoracic muscle and the internal intercostal muscle will be identified. A total of 15 mL of 0.25% bupivacaine will be injected into the interfascial plane, between the transversus thoracic muscle and the internal intercostal muscle between the fourth and fifth costal cartilages connecting at the sternum. Pleural downward displacement will be used as an ultrasound endpoint.

Patients positioned supine with the ipsilateral arm abducted and externally rotated. The infra-clavicular and axillary regions will be cleaned with chlorhexidine. The skin point of and once the structures are identified with ultrasound, the probe will be positioned under the lateral third of the clavicle. After locating the subclavian artery, the axillary artery and the axillary vein we will move the probe distally towards the axilla, until the pectorals major muscle is identified. We will start counting the ribs, from 1st rib under the axillary artery and maintaining the pectorals major. Serratus anterior muscle cover 2nd, 3rd, 4th rib, this point being the entrance into the anterior axillary line we will use atraumatic needle with extension line and electrode for nerve stimulator (Stimuplex D). We will inject 10ml of 0.25% bupivacaine between the pectorals muscles first, then inject 20ml of 0.25% bupivacaine.