Pectoral Nerve Blocks for Breast Augmentation Surgery

Discussion

This prospective study shows that preoperative combined PECS blocks I and II associated with a systematic multimodal analgesia regimen reduced maximal pain intensity assessed by numerical rating scale during the first postoperative 6 h in patients scheduled for breast augmentation surgery. The PECS group had a statistically significant lower pain from day 1 to day 5. The cumulative amount of overall opioid consumption was also statistically lower for the PECS group from hour 6 after extubation to day 1 and from days 1 to 5.

Analgesia for aesthetic breast surgery receives less attention compared with cancer surgery. However, pain generated by breast augmentation surgery is quite similar to pain after modified radical mastectomy.^[13] Indeed, the dissection required for the implant involves the disruption of the pectoralis major muscle and its attachments to the ribs. In some cases, the muscle fibers are split to access the plane between pectoral muscles, and the stretch of the pectoralis major muscle can be substantial. The major source of pain from submuscular breast augmentation is myofascial and transmitted by the pectoral nerves. The skin incision may be periareolar, inframammary, or transaxillary. Nerves involved in pain related to skin incision are, respectively, the anterior and lateral branches of intercostal nerves from T2 to T4, from T5 to T6, or the long thoracic nerves, and sometimes some branches from supraclavicular nerves, depending on implant size.^[13]

PECS is a relatively new fascial plane block that aims to provide analgesia to the upper anterior chest wall.^[15] PEC I targets the medial and lateral pectoral nerves to anesthesize the pectoralis muscles. PEC II targets several divisions of the intercostal nerves and the long thoracic nerve. These nerves need to be blocked to provide effective analgesia during breast surgery.^[13,33]

PECS is associated with less complications than other described techniques for breast surgery, like paravertebral blocks. Indeed, they are minimally invasive with a rapid spread use.^[34] These blocks have been used for analgesia during and after breast cancer surgery with relevant analgesic effect.^[35] There is still a paucity of high-quality evidence supporting the analgesic benefit of these approaches in aesthetic breast surgery. Small recent randomized controlled trials assessed PECS for breast augmentation surgery, with heterogeneous results.

Ekinci et al.^[21] compared postoperative analgesic effect of PEC 1 alone with no block (30 patients in each group) and reported a difference in fentanyl consumption in their primary outcome (25.7 vs. 18.2 mg IV morphine equivalent respectively at day 1 [P = 0.008]). Using a PECS and serratus plane block compared with a sham block with no additional systemic analgesic in postoperative care (15 patients in each group), Schuitemaker et al.^[22] failed to demonstrate a significant difference in their first goal, a decrease in intraoperative hemodynamic variability, but reported a 40% numerical rating scale decrease in the PACU (5.3 ± 2.3, vs. 2.9 ± 2.7 [P = 0.014]) without any difference in morphine consumption. Karaca et al.^[23] compared postoperative PECS block with no block and a nonopioid analgesia regimen without acetaminophen (27 patients in each group). In their primary outcome, the 24-h IV morphine consumption was nearly 4-fold lower with PECS (mean SD, 11.6 vs. 37.9 mg; P < 0.001). The numerical rating scale was also significantly lower with PECS. Our study presents substantial differences. This is the first study in which PECS block was realized immediately after general anesthesia, leading analgesia of area of interest during all surgeries. Preincisional regional anesthesia techniques offer better pain relief and decreased intraoperative opioid consumption and may decrease postoperative opioid use.^[36] Therefore, a systematic nonopioid and multimodal analgesic regimen was applied for all patients, associating acetaminophen and nonsteroidal anti-inflammatory drugs before rescue opioids with respect of current international guidelines.^[8,24–27] A systematic double prophylaxis for postoperative nausea and vomiting according to guidelines and Apfel scores was also applied for all patients.^[37] Consequently, we report similar pain scores with two- or threefold lower morphine equivalent consumption and lower postoperative nausea and vomiting rate than previous works in both the PECS and control groups. Thus, this study is a demonstration of how patients may benefit from associating several analgesics (systemic or regional analgesia), acting on different receptors, to improve postoperative pain outcomes.^[8]

In the pathway of enhanced recovery after surgery, regional anesthesia is a major component of perioperative pain management.^[38] Searching for optimal analgesia with less invasive techniques made interfascial plane blocks increasingly popular.^[39] Fascial plane blocks such as PECS blocks, are based on the dissection of intermuscular spaces to target the nerve branches progressing within these spaces. However, no surgeon reported any change in their landmarks and dissection planes in this in the study. In our experience, as in previous studies, no additional operative difficulties related to the realization of these blocks have been reported. Several interfascial plane blocks have been indeed assessed for analgesia after breast surgery.^[13] Thoracic paravertebral blockade is suggested for major breast surgery but not in aesthetic breast augmentation surgery. Indeed, it may be not sufficient with an incomplete anesthesia, because supraclavicular branches from the superficial cervical plexus, pectoral nerves, long thoracic and thoracodorsal nerves are not blocked with thoracic paravertebral blockade.^[13,17] On the other hand, thoracic paravertebral blockade involves the risk of pneumothorax, spinal cord trauma, sympathetic block, and hypotension. More rarely, thoracic paravertebral blockade may become an epidural block or may result in total spinal anesthesia. Thus, it may be not suitable for a day-case surgery, considering the possible side effects.^[17,40] Recently, Hussain et al.^[16] undertook this systematic review and meta-analysis to identify the potential clinical role of PECS. They found no differences in pain scores or opioid consumption between the two groups for the first 24 h after breast cancer surgery, and both were superior to systemic analgesia alone.^[18]

Erector spinae plane block has been proposed as an alternative to PECS block in patients scheduled for major breast surgery. In two recent studies, the authors failed to demonstrate the superiority of the erector spinae plane block, with statistically significantly lower opioid consumption and pain scores in the PECS group.^[41,42]

There are several limitations with this study. The main limitation was not using a placebo in the control group. PECS as an interfascial plane block, need large volumes of local anesthetic.^[39] We thought that injection of 10 and 15 ml of saline solution may generate a pain by itself. Concerning the potential imprecision of any results due to unreliability of outcome measurements, misdiagnosis, or misclassification of events, the primary outcome was self-measured by the patients themselves. Although subjective by nature, this precluded the potential bias of a measurement made by observers. In addition, a very strict blinding procedure was performed using different anesthesia teams for the research (procedure of PECS) and the general management (patient management and data recording). Formal dermatomal cold-sensation testing was not undertaken. It would have caused a loss of the blind. The absence of this testing means a lack of confirmation of correct block efficiency. However, cold stimulation may be poorly correlated with the spread and efficiency of regional analgesia for postoperative pain.^[43] Postoperative hyperalgesia was also not assessed. Regional anesthesia is effective to prevent from hyperalgesia.^[44] That may explain the opioid consumption difference during the last 4 days of follow-up.^[44] All surgical procedures were not the same. Indeed, prostheses may be prepectoral or subpectoral, which may lead to different postoperative pain.^[39–45] Finally, 136 patients were screened for eligibility, and only 74 were randomized. Some patients refused the randomization, wanting the certain realization of PECS block, and the main plastic surgeon quit one center unexpectedly, which explains the slowdown in the rate of inclusions. Finally, several sources of bias could substantially impact interpretation of the trial. However, the randomized double-blind design should provide reassurance.

Conclusions

Preincisional PECS block associated with recommended multimodal analgesia is an effective and safe technique that provides better postoperative analgesia immediately and over 5 days of follow-up; moreover, it is associated with lower opioid consumption. Further studies are required to assess the clinical effect of PECS for preventing chronic postsurgical pain after breast augmentation.

Anesthesiology. 2021;135(3):442-453. © 2021 American Society of Anesthesiologists | Lippincott Williams & Wilkins