The Mid-point Transverse Process to Pleura Block Versus Serratus Anterior Plane Block for Postoperative Analgesia After Modified Radical Mastectomy

"Group I: (Serratus Anterior Plane Block (SAPB) Group) (n=15):~The patient will lay on her side with arm brought forward, the linear US transducer probe (10-12 MHz) will be placed in the midaxillary line and then moved caudal from second rib until the sixth intercostal space. At this point, the subcutaneous tissue and serratus muscle will be identified in the superficial plane, whereas the external intercostal muscles will be identified in the intermediate plane and finally in the deep plane the ribs, pleura and lung will be identified. The needle will be advanced from caudal to cranial direction. In-plane technique will be used until the tip of the needle placed between the serratus anterior muscle and the external intercostal muscle (deep SABP) . A volume of titrated bolus of 20 ml of bupivacaine 0.5% will be injected after aspiration to avoid intravascular injection."

In the lateral postion, the T4 spine will be counted by ultrasound, and high frequency linear US transducer probe (10-12 MHz) will be placed longitudinally, approximately 2.5 cm lateral to the midline the needle will be advanced in plane from cranial to caudal direction. The desired end point for the needle tip will be the midpoint of the line between the posterior border of the transverse process of T4 and the pleura(injection will be deep (anterior) to the posterior aspect of the vertebral transverse process but superficial to the superior costotransverse ligment),the needle tip dose not enter the paravertebral space , a volume of titrated bolus of 20 ml of bupivacaine 0.5% will be injected after aspiration to avoid intravascular injection,pleural displacement and bowing of erector spinae will be observed at the side of injection .