Percutaneous nephrolithotomy (PCNL), a minimally invasive surgical procedure used to treat patients with large kidney stones (1), is usually associated with significant pain in the perioperative period. PCNL is performed in the prone position and although neuraxial anaesthesia has been successfully employed for the procedure, most patients and physicians prefer general anaesthesia for the same (2).

Intravenous analgesics such as opioids are routinely employed for the management of intraoperative and postoperative pain in these patients. These are often associated with significant adverse effects such as nausea and vomiting, pruritis and respiratory depression which may affect the postoperative course in these patients (3). Nonsteroidal anti-inflammatory (NSAID) drugs are of limited use in these patients as they are likely to have deranged kidney function tests (4).

In order to minimize the adverse effects of intravenous analgesics and to optimize perioperative analgesia, supplemental regional analgesia techniques such as epidural block, paravertebral block and intercostal nerve block have been used for the management of pain (5),(6). Epidural anaesthesia may be associated with complications like paraplegia, cauda equina syndrome, epidural hematoma, infection, intravascular injection, urinary retention etc. Although these complications are rare, they are severe enough to pose high morbidity to the patient (3). Thoracic paravertebral block is also as effective as epidural anaesthesia but is more technically demanding and requires multilevel injections to achieve large dermatomal coverage (7).

The ultrasound-guided erector spinae plane (ESP) block is a recently described technique which involves injection of local anaesthetic in plane deep to erector spinae muscle.Cadaveric investigation indicates that injection of 20-mL solutioninto the fascial plane deep to the erector spinae muscle at the levelof the T5 transverse process can result in injectate spread betweenthe C7 and T8 vertebral levels. Given that the erector spinae muscleextends inferiorly to the lumbar spine, injection into the ESP ata lower vertebral level (e.g, T7 or T8) should result in spread to thelower thoracoabdominal nerves as well. In addition, because the mechanism of action of the ESP block involvespenetration of local anaesthetic into the thoracic paravertebralspace, it anaesthetizes not only the ventral rami of spinal nerves but also the rami communicantes that contain sympathetic nervefibers. The ESP block thus has the potential to provide both somaticand visceral sensory blockade (8), (9).

The main sources of acute pain after PCNL are visceral pain originating from the kidneys and ureters and somatic pain from the incision site. Visceral pain is conducted largely through T10–L2 spinal nerves whereas the cutaneous innervation of the incision site is by the T8–T12 nerves. Thus, ESPB would likely be a good regional anaesthetic technique for PCNL (3), (10).

Also, the literature suggests that it is easier to perform as landmarks for the identification of the site of block are readily identifiable and good dermatomal coverage with a single puncture. Another important advantage lies in that the block site is away from major vascular structures and pleura and therefore is associated with less incidence of complications as compared to PVB (8).

We hypothesized that ESPB would be a good adjunct for providing perioperative analgesia and lead to reduction in total opioid consumption in the perioperative period following PCNL. Although ESPB has been used for many procedures, there is no data till date for its use for the management of pain in patients undergoing percutaneous nephrolithotomy. Hence, we aim to assess the efficacy of ESPB in providing perioperative analgesia in patients undergoing PCNL.

References

1.            1.Vicentini FC, Gomes CM, Danilovic A, ChedidNeto EA, Mazzucchi E, et al. Percutaneous nephrolithotomy: Current concepts. Indian J Urol2009;25:4-10.

2.            2. Hu H, Qin B, He D, Lu Y, Zhao Z, Zhang J,et al. Regional versus General Anesthesia forPercutaneous Nephrolithotomy: A Meta-Analysis.PLoS ONE 2015;10(5): e0126587.

3.           3. Miller’s Anesthesia eighth edition, Ronald D. Miller, MD, MS, Neal H. Cohen, MD, MS, MPH, Lars I. Eriksson, MD, PhD, FRCA, Lee A. Fleisher, MD, Jeanine P. Wiener-Kronish, MD, William L. Young, MD.

4.            4. Hörl WH. Nonsteroidal Anti-Inflammatory Drugs and the Kidney.Pharmaceuticals (Basel). 2010; 3(7): 2291–2321.

5.           5.  Li C, Song C, Wang W, Song C, Kong X. Thoracic Paravertebral Block versus Epidural Anesthesia Combined with Moderate Sedation for Percutaneous Nephrolithotomy.Med Princ Pract. 2016 Aug; 25(5): 417–422.

6.     6. Ozkan, D., Akkaya, T., Karakoyunlu, N. et al. Effect of ultrasound-guided intercostal nerve block on postoperative pain after percutaneous nephrolithotomy.Anaesthesist. 2013 Dec;62(12):988-94.

7.       7. El-Boghdadly, K., Madjdpour, C., & Chin, K. J. (2016). Thoracic paravertebral blocks in abdominal surgery – a systematic review of randomized controlled trials.Br J Anaesth. 2016 Sep;117(3):297-308.

8.            8. Forero M, Adhikary SD, Lopez H, Tsui C, Chin KJ. The erector spinae plane block: anovel analgesic technique in thoracic neuropathic pain. RegAnesth Pain Med2016;41:621–7.