Evaluating the Effectiveness of Bilateral ESPB in Addition to Standard Analgesia at Reducing Opioid Consumption

Breast surgery is among the most common procedures performed at ambulatory surgery centers. Whether for cosmetic or cancer indications, mastectomy and reduction mammoplasty are being performed under general anesthesia with standard multimodal pharmacologic analgesia. Regional anesthetic techniques have become increasingly prevalent in the management of postoperative analgesia. In oncologic surgery, regional anesthetic techniques have demonstrated a lower incidence of recurrence or metastasis of breast cancer compared to opioid analgesia. The breast has complex innervation, receiving innervation from C5-T7, thus posing a challenge to the regional anesthesiologist.

Current regional techniques for breast and other thoracic surgeries, such as open heart surgery, include the PEC I, PEC II, serratus anterior block as well as the paravertebral block. Of these options, the paravertebral block is heralded as the gold standard for multimodal analgesia in breast surgery. Unfortunately, the paravertebral block carries with it the risk of pneumothorax due to its proximity to the pleura. This risk is also increased when an inexperienced provider is performing the block, which is common on an academic institution. As a result, the PEC I, PEC II and serratus anterior blocks have gained traction, is that they carry less risk of adverse events. One drawback of the PEC blocks and serratus anterior block is that they may not achieve adequate anterior spread and complete coverage of the surgical field, making them less effective at providing adequate post-operative analgesia. Due to these drawbacks, the erector spinae plane block (ESPB) has begun to gain traction as the regional technique of choice for breast surgery. The ESPB is a myofascial block alternative to the paravertebral block. \[1\] It is performed by injecting local anesthetic in the plane between the erector spinae muscle and the spinal transverse process. The ESPB is thought to be safer than the paravertebral block because the transverse process acts as a barrier to the pleura. It has been postulated that local anesthetic spread reaches the paravertebral space and in fact, cadaveric studies have shown dye spreading to involve the ventral and dorsal rami of spinal nerves. It is because of this mechanism of action that this block has been call the "paravertebral by proxy." The spread of the local anesthetic is volume-dependent, and has been seen to anesthetize between 3-8 vertebral levels when using local anesthetic volumes of 15-20mL. The ESPB has been used successfully for analgesia in open-heart surgery as well as in chronic thoracic neuropathy secondary to herpetic neuralgia. Proponents of the erector spinae block prefer it to the paravertebral block for its ease to perform and seemingly safer profile.

The investigators seek to explore the proposed benefits of the erector spinae plane block in our patients undergoing bilateral breast reduction mammoplasty. Reducing overall opioid use and enhancing recovery after surgery are areas of great importance in the ambulatory, outpatient setting. The investigators hope to show the positive impact of ESPB on both of important perioperative factors.