Introduction Pain after thoracic surgery is of moderate-to-severe intensity and can cause increased postoperative distress and impair functional recovery. Peripheral nerve blocks (PNBs) have gained considerable attention in perioperative pain management as a method to reduce systemic opioid consumption and improve pain control. This narrative review aims to describe the different peripheral regional blocks in the context of thoracic surgery. PubMed and Embase were searched for all RCTs and reviews involving adult participants undergoing thoracic surgery with PNB as analgesia. A total of 157 articles were retrieved according to the search strategy in Pubmed and 234 in Embase. After screening of the title and abstract,92 articles (68 RCT,24 reviews) were selected finally. Regional anaesthesia is a useful choice in thoracic surgery and peripheral nerve block can improve patient outcomes. Due to the lack of RCTs, it is still not possible to determine the most appropriate block in individual surgical situations, although we have the PROSPECT recommendations.

Discussion Intercostal nerve blocks are a relatively easy procedure to perform and can provide potent analgesia in a fast and reliable manner48. One advantage of intercostal blocks is that they can be performed under direct visualisation in the pleural cavity by the surgeon in the field or percutaneously by the anaesthetist. Due to the circumscribed nature of the intercostal nerves innervating the chest wall, multiple levels of injection are required to ensure adequate analgesia.

A systematic review and meta-analysis revealed that the administration of a single-injection ICNB among adults undergoing thoracic surgery was associated with a modest reduction in pain scores during the initial 24-hour postoperative period. Intercostal nerve block analgesia was superior to systemic opioid-based analgesia, noninferior to TEA, and marginally inferior to PVB. Because ICNB analgesia was also associated with better pulmonary function and a reduction in the risk of pulmonary complications, these findings were clinically relevant.

The data suggested that the benefit of ICNB analgesia decreases progressively and disappears at 24 to 48 hours after surgery. Reliance on ICNB after this period may result in an abrupt lack of analgesia or rebound pain, represented by higher pain scores at 24 hours after surgery for dynamic pain and 48 hours after surgery for static pain.

These factors have motivated further research with the objective of developing a more efficient technique.

The anterior serratus plane block was the first describen. It is a type of regional anaesthetic that is simple to perform and highly effective in providing analgesia. It has no adverse effects, such as respiratory or circulatory depression. In comparison to traditional local infiltration anaesthesia, SAPB necessitates a reduced quantity of local anaesthetics, is devoid of the potential for local anaesthetic poisoning, and extends the duration of analgesia through catheterisation. In comparison to a thoracic epidural block, SAPB does not result in spinal cord injury, epidural haematoma, respiratory depression, or fluctuations50. In comparison to an intercostal nerve block, a SAPB is a relatively simple procedure, necessitating fewer injections and presenting a lower incidence of complications such as pneumothorax. In comparison to a thoracic paravertebral nerve block, a SAPB is a less challenging procedure with no risk of orthostatic hypotension or urinary retention51. In comparison with total intravenous analgesia, SAPB has the advantage of not causing adverse reactions such as nausea and vomiting, excessive sedation, or respiratory depression caused by opioids. Furthermore, opioids are a more expensive option. Consequently, future research on SAPB may be conducted in an ambulatory setting, such as during breast nodule resection, breast prosthesis implantation, invasive procedures, such as breast tissue pathological biopsy and treatment of intercostal neuralgia.

A relatively recent regional anaesthetic technique that offers significant advantages and has been gaining popularity in the context of thoracic surgery is the erector spinae block. As with numerous other regional techniques, this block can be performed as a single-shot procedure with an appropriate volume of local anaesthetic, or alternatively, by placing a catheter for continuous infusion. Furthermore, this technique is demonstrating encouraging results in the treatment of trauma patients with rib fractures.

The existing literature on the use of ESPB in thoracic surgery is limited to case reports, editorials, and a few clinical trials. The ESPB has been demonstrated to be an efficacious peripheral technique for postoperative pain management in this cohort of patients. These findings are in accordance with the results of the present study, which demonstrated that ESPB provided adequate analgesia following minithoracotomy. The average static and dynamic NRS scores remained below 3 throughout the follow-up period, and the number of requests for additional analgesic drugs was low.

In comparison to TEA and TPVB, ESPB appears to be a safer option, with a minimal risk of pleural puncture and epidural spread. Furthermore, the risk of coagulopathy should be minimal, given that the procedure is performed at a distance from the spinal cord or the epidural venous plexus, thereby avoiding the risk of epidural haematoma. In the initial 48 hours following surgery, patients undergoing continuous ESPB exhibited reduced opioid requirements and reported diminished pain compared to those undergoing ICNB55. There were no differences in respiratory muscle strength, postoperative complications, or time to hospital discharge. However, TPVB appeared to be the preferable method compared with ESPB and ICNB, with a more successful analgesia and less morphine consumption. In comparison with other regional anaesthetic techniques, a variety of outcomes have been documented. Although statistical analysis indicated that ESPB was less effective than thoracic paravertebral block and intercostal nerve block and more effective than serratus anterior plane block in postoperative analgesia, the clinical differences remain unclear. The incidence of haematoma was found to be lower in the ESPB group than in the other groups (odds ratio 0.19, 95% CI 0.05-0.73)20.

Erector spinae plane (ESP) block and serratus anterior plane (SAP) block promise effective thoracic analgesia compared with systemically administered opioids. Compared with SAP, ESP provides superior quality of recovery at 24 h, lower morbidity, and better analgesia after minimally invasive thoracic surgery. However, the SAP block can play an important role in the management of pain after thoracic surgery by reducing both pain scores and 24-h postoperative opioids consumption. In addition, there is fewer incidence of PONV in the SAP block group.

Regarding the pain control in emergency department Dr Armin recommends ESPB in blunt or penetrating thoracic trauma27.

Analgesia in breast surgery has different connotations, as it involves both intercostal and pectoral nerves. The results of some meta-analysis demonstrate that the Pecs II block is a valuable adjunct for postoperative analgesia in patients undergoing breast cancer surgery. Compared with patients who received only systemic analgesia, patients who received a Pecs II block not only had significantly less pain at all measured postoperative time-points up to 24 h but also a time to first analgesia request that was prolonged by 5 h on average. Although some might question the clinical significance of a 1–2-point reduction in pain scores on a 0–10 scale, it is worth noting that this represents a reduction of 39–55% from the average pain scores of 2.4–3.5 reported in the control groups. Furthermore, this was achieved with a simultaneous 59% reduction in 24-h opioid consumption. Although the role of peri-operative opioids in tumour metastasis remains uncertain, the importance of fully attenuating the peri-operative stress response possible is unquestioned56 One reason for the popularity of the Pecs II block is that it is a simpler and safer alternative to a thoracic paravertebral block, which many find a challenging technique to perform.

Conclusions With the development of ERAS protocols, the classical approach to post-operative pain control has changed; narcotics are no longer enough. In this area, peripheral nerve blocks have shown good results.

Nowadays, peripheral nerve blocks and their different approaches have shown to be an alternative to central blocks (paravertebral and epidural). ICNB, SAPB, ESPB and PECS are associated with a reduction in pain during the first 24 hours after thoracic surgery and reduce the amount of opioids during the postoperative period. Furthermore, the current literature supports that some of them offer non-inferior or comparable analgesic efficacy to a TPVB, suggesting that they may also be beneficial in cases where TEA and PVB are not indicated, and even the Pecs II block warrants consideration as a first-line option for regional analgesia in breast surgery.