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

Breast cancer is the most common cancer in women both in the developed and less developed world. In 2012, it represented about 12 percent of all new cancer cases and 25 percent of all cancers in women (Jain et al., 2020).

Surgery is one of the mainstays of treatment, and a procedure called modified radical mastectomy (MRM) is now a standard surgical treatment for early stage breast cancers.These procedures cause significant acute pain and may progress to chronic pain states in 25-60% of cases (Andersen and Kehlet, 2011).

Though various risk factors have been suggested, inappropriate acute postoperative pain management has been associated with the development of chronic post mastectomy pain, a complex post-surgical pain syndrome that may occur following any type of breast surgery (Macrea, 2001). The traditional opioid based analgesia remains the mainstay, however. Different techniques including regional local anaesthetic infiltration, paravertebral and neuroaxial analgesia, anti\_neuropathic analgesics and NMDA antagonists have all been used either singly or in combination, (Macrea, 2001). Post operative pain is usually acute nociceptive pain, it occurs as normal response to noxious insult or injury (Dworkin et al., 2007) .

Inadequately controlled pain negatively affects quality of life, functional recovery and increase the risk for post-surgical complications (Apfelbaum, 2003).

After the application of ultrasound in anaesthetic practice,several blocks have been described recently,Serratus anterior plane blocks performed at the axillary fossa within a region bounded by the anterior and posterior axillary lines and th 3rd to 6th ribs (Chin et al., 2021), in which the intercostobrachialis nerve, lateral cutaneous branches of the intercostal nerves (T2-T9),long thoracic nerve,and the thoracodorsal nerve are located in a compartment between the serratus anterior and the latissimus dorsi muscles (Blanco et al., 2013).

The MTP block described by Costache et al. (2017) is a new block described for thoracic surgery, it involves deposition of the local anesthetic drug midway between the transverse process and the pleura. Postulated that the local anesthetic deposited at this point will reach the paravertebral space through several possible mechanisms, such as medially through the gap between the superior costotransverse ligament (SCTL) and vertebral bodies, through fenestrations in SCTL, and laterally through the internal intercostal membrane, the neural target will be the dorsal and ventral rami of spinal nerves, spanning 1-3 levels cranial and caudal to the level of injection,the advantage of the MTP block over the conventional thoracic paravertebral block is that the visualization of SCTL is not required, which might be difficult in patients with obesity. The second advantage is that the target point of the needle is very superficial and far from structures, such as the pleura and neurovascular bundles ,making this novel block much safer (Syal et al., 2020).

2.AIM / OBJECTIVES

The aim of work is to evaluate The Effectiveness of Ultrasound Guided mid-point transverse process to pleura block versus the serratus anterior plane block for postoperative analgesia after modefied radical mastectomy.

• The total number of doses of the rescue analgesia that will be received in the 24 hours postoperatively if the NRS pain score at rest ≥4 [Time frame: 24 hours post- operative]