s Serratus Anterior Block for Perioperative Analgesia

Overview

Modified radical mastectomy is one of the commonly performed breast surgery. Postoperative pain following mastectomy should be minimised, as in a number of women it may chronically persist for months in the form of postmastectomy pain syndrome. Morphine administration for acute pain after mastectomy surgery has many side effects. Regional block techniques as paravertebral block and thoracic epidural anathesia has possible complications and technical difficulties. The new alternative regional techniques such as erector spinae plane block and serratus anterior plane block are clinical trials for providing a safe, easy and painless anesthetic procedure with good hemodynamic and recovery profile with adequate perioperative analgesia for a large section of patients undergoing mastectomy operation in order to reduce opiods consumption and subsequently avoid opiod-related adverse effects.

Breast cancer is the most common malignancy of women all over the world. Unfortunately, two-thirds of women who undergo breast cancer surgery are reported to develop chronic pain in the postoperative period. Surgery type, radiation therapy, and clinically acute pain are the most important risk factors for the development of more intense chronic pain. With improved diagnostic techniques and treatment regimens, prognosis in breast cancer is improving, with the 5-year survival of patients diagnosed with primary breast cancer having increased to approximately 85%. Persistent post-surgical pain states in this group is reported in 30-50% of patients, up to half of whom may have pain well beyond 5 years. Over one-third of patients who underwent breast cancer surgery have inadequately controlled acute post-operative pain. There are several ways to manage pain after mastectomy. Common systemic medications, particularly opioids, have different side effects, such as itching, nausea, vomiting and respiratory depression. Non-steroidal anti-inflammatory drugs are associated with impaired renal function and hemorrhagic disorders. Regional anesthesia has been believed as one of the formats for effective perioperative pain control. Regional blocks using ultrasound-guide has become a perfect supplement to general anesthesia for extending analgesia after modified radical mastectomy. The advantage includes post-operative pain relief prolongation, a decrease in analgesic requirement post-operatively, a reduction in nausea and vomiting scores and probability for ambulatory discharge and hospital stay. The complex innervation of breast tissues poses a great challenge for the anesthesiologists to provide adequate perioperative analgesia by ultrasound guided regional blocks. Thoracic epidural, interscalene brachial plexus block, paravertebral block, pectoral nerve I and pectoral nerve II blocks have been used in different studies with good results. There are also technically simple regional blocks as ultrasound-guided Serratus anterior Plane (US-guided SAP) block and erector spinae plane (US-guided ESP) block which can be used effectively for this purpose. Forero et al. described ultrasound-guided Erector Spinae Plane (US-ESP) block as a novel analgesic technique in which local anesthetic injection is done beneath the erector spinae muscle. Previous studies reported effective postoperative pain reduction with ESP block after radical mastectomy surgery. Nevertheless, few studies have compared the efficacy of ESP block with another block technique. The Serratus Anterior Plane block (SAP) provides anterolateral and partial posterior thoracic wall analgesia, affecting dermatomes from T2 to T9. SAP is affecting predominantly the lateral cutaneous branches of the thoracic intercostal nerves, along with intercostobrachial, thoracodorsal and long thoracic nerves. The block is performed further posteriorly and caudally than Pectoral Nerve Block-2, where the target nerves are located between the serratus anterior and the latissimus dorsi muscles.