ESP Block for Laparoscopic Nephrectomy Surgeries

While post-operative pain seems to be slightly decreased compared to open nephrectomies, pain from laparoscopic nephrectomy is still significant and opioid consumption is similar.Adequate management of post-operative pain is imperative in early post-operative mobilization. ¬Although opioids have been a mainstay for the treatment of post-operative pain, other strategies should be considered as opioids are associated with adverse effects, the potential for long-term opioid use, and even death. There have been an increasing number of opioid related deaths with 2,066 apparent opioid-related deaths in Canada over the first half of 2018. With the need to address the worsening opioid crisis, it is essential that other non-opioid strategies are explored and considered. Multimodal anesthesia has been one effort to reduce opioid use post-operatively. Increasingly, the literature shows that peripheral nerve blocks reduce post-operative opioid consumption in a vast variety of surgeries.

Traditionally patients undergoing laparoscopic nephrectomy have opioid patient controlled analgesia pumps (PCAs) for post-operative pain control. PCA is widely recognized as an effective technique after laparoscopic nephrectomy to reduce pain scores. A meta-analysis of 49 articles showed PCA had better postoperative pain control than nurse administered analgesics over most time intervals with higher patient satisfaction. Complications of a PCA include respiratory depression, confusion or sedation, nausea, pruritus, ileus, and insufficient analgesia. Paravertebral blocks (PVB) have recently showed promise and increasing clinical uptake due to a growing use of ultrasound-guided regional anesthesia. They provide good pain control in patients undergoing thoracic and abdominal surgeries. In PVB, local anesthetic is injected near the thoracic spinal nerve at its exit from the intervertebral foramina, which results in unilateral somatic and sympathetic nerve blockade in multiple continuous thoracic dermatomes above and below the site of injection. However, this technique is technically challenging, time consuming, and carries a risk of pneumothorax. Fascial plane blocks are increasingly used as an alternative regional anesthetic strategy for abdominal surgery.

Recently ultrasound-guided Erector Spinae Plane (ESP) block was described in which local anesthetic is injected around the erector spinae muscle which tends to block the dorsal and ventral rami of the thoracic spinal nerves. There is growing evidence of its use in a wide range of surgeries. The appeal of the ESP block is in providing analgesia without the potential for needle pleura interaction and the consequent risk of pneumothorax. This interfascial block involves ultrasound guided injection of local anesthetics under the erector spinae muscle and superficial to transverse process of thoracic vertebrae at appropriate level. The ESP block targets the dorsal and ventral rami of the spinal nerves as they leave the intervertebral foramen. Cadaveric examination of ESP block showed extensive cranial-caudal spread of the block, approximately four dermatomes above and below the site of injection. The fact that the site of injection is distant from the spinal cord and pleura, increases the safety of the ESP block as compared to a paravertebral block. The transverse process is easily visualized on ultrasound and acts as a backstop for the needle, preventing excessively deep placement. Of importance, a catheter can also be placed easily during the ESP block allowing continuous infusion and prolonged analgesia. Given the importance of providing adequate analgesia in patients undergoing laparoscopic nephrectomy and the lack of consensus amongst surgeons and anesthesiologists for the optimal analgesic technique, we are proposing a pilot randomized controlled trial (RCT) to determine the feasibility of a larger RCT to compare continuous ESP blockade vs a Sham blockade. Both groups will receive opioid PCA and other multimodal analgesia combined with opioid PCA versus opioid PCA alone.

Literature review: We conducted a review via Pubmed looking at all studies associated with "erector spinae block". Of the studies found, 123 relevant studies were reviewed. The studies included 92 case reports and 4 randomized control trials, with the others being anatomical reviews, editorials, or small review articles. Of these, there were only 4 patients from 1 case series article where patients received ESP blocks for laparoscopic nephrectomies. None of these patients required post-operative opioids in addition to their ESP block infusions. We also reviewed clinicaltrials.gov for ongoing and proposed trials related to the ESP block. Currently, we identified 51 studies involving the ESP block. The vast majority of these revolved around thoracic and general surgery, including some randomized controlled trials. There was only 1 proposed trial studying the use of the ESP block with nephrectomies, but this one was evaluating surgeries