I’ve been hoping and trying to post a weekly or biweekly reader response in the PAAD. Indeed, within many of the PAADs you’ve probably realized that our writer/editors often present provocative and thought provoking questions for you to consider. This is very deliberate. We really want your feedback. Please free to email me or John Fiadjoe and we’ll do our best to post them. Myron Yaster MD
From Ben Walker MD
I found the recent PAAD's on ESP catheters and intercostal nerve cryoanalgesia for pectus repair quite interesting. I have taken care of patients for the Nuss procedure with a variety of regional techniques, PCA +/- methadone, and more recently cryoanalgesia. Our hospital was part of a dual-center RCT comparing epidural catheters to PCA with LOS as the primary outcome (1). We did not find a difference in LOS, and no real clinically significant differences in pain, other than slightly better pain control in the early postoperative period and better pain control in the PCA group when the epidural was discontinued, which is what one would expect given the known efficacy of thoracic epidurals and the challenges of transitioning off them after the Nuss procedure. After that, our surgeons requested a PCA protocol, and we did a handful of paravertebral catheters in the interim. We eventually settled on a PCA/methadone protocol similar to what we were using for posterior spinal fusion. For the past four years, we have been using cryoanalgesia, which has been performed on about 100 patients. We did a retrospective comparison of the first 35 patients using cryo to a historical cohort on a PCA/methadone protocol (with a few thoracic epidurals), and found a 90% reduction in opioid use in the cryo group, with severe pain reported by 5% in the cryo group vs 40% in the non-cryo group at any point in the hospital stay, and LOS was reduced to 1 day from 4 (2). Two of 35 cryo patients reported neurologic symptoms after discharge and were given brief courses of gabapentin (< 6 weeks) with complete resolution of symptoms. Unfortunately, we have not continued to collect long-term data on neurologic symptoms, but informal queries of our 3 surgeons that do this procedure resulted in a similar rate (about 5%).
All we have done is provide yet another small sample showing about 5% incidence of short-term neurologic symptoms, and I wholeheartedly agree with Dr. Chidambaran that further research is needed, especially regarding possible long-term adverse outcomes. However, one could say that the efficacy of this technique for Nuss has been well-established, and I do not think that any of our regional techniques will approach the levels of reduction in opioid-use, severe pain, or LOS that can be achieved with cryo (and these effects persist well beyond the duration of our ambulatory PNC's). We should also keep in mind that if we do rigorous neurological testing and questionnaires, we are much more likely to encounter positive findings (which may or may not be clinically significant to the patient). When we do similarly rigorous questioning after peripheral nerve blocks, we find a much higher rate of persistent neurologic symptoms than are reported in larger databases such as the PRAN, which are better for detecting rare and often severe complications (3). Prior to cryo, the Nuss procedure was still associated with neurologic sequelae, likely due to surgical trauma to intercostal nerves with bar fixation as Myron speculated, so there will be confounders. As noted in some studies, it is likely that we would see fewer long-term complications in younger patients because we know that recovery after traumatic neurologic injury is inversely proportional to age (4,5).
Our colleagues in Cincinnati should be commended for developing a comprehensive ERAS protocol for the Nuss procedure. By optimizing all aspects of perioperative care of these patients, many positive outcomes can be achieved. However, as much as cryo is an attractive new technology for our surgical colleagues, the ESP block has been enthusiastically adopted by many in our community prior to the availability of any rigorous safety or efficacy data. Here I would respectfully disagree with Dr. Chidambaran that there are well-demonstrated safety data for the ESP because this would take thousands of patients to establish, and any peripheral nerve block is not without the danger of its own neuropathic sequelae much like cryo. We are also lacking any large RCTs demonstrating efficacy as most of the literature centers on case reports and series. The one meta-analysis in pediatric patients demonstrated only a small improvement in pain scores compared to no block at all (6), so there is reason to curb our enthusiasm with this approach. The primary advantage of the ESP is technical ease of placement and a distance from any critical structures. This is also the primary disadvantage, as we are depositing local anesthetic near the dorsal rami and then hoping it travels on its own through small holes in dense connective tissue to the paravertebral space (or at least the anterior rami). I think this is analogous to placing a femoral block superficial to the fascia iliaca. We may get some local anesthetic that makes it to the nerve, but it will likely be a patchy and unreliable block. Both cadaver and clinical studies have rendered very inconsistent results with ESP blocks, especially for analgesia to the anterior chest, and it's unclear if the benefits are from neural blockade vs systemic absorption. I think we can say that an ESP block is better than nothing, but we need to be honest about the limitations and lingering questions with this technique. Indeed, some of our respected pediatric regional colleagues are ready to change the name to the "RIP" block (7), but I think we can agree that both the ESP and cryo need further study.
References
Sujka JA, Dekonenko C, Millspaugh DL, Doyle NM, Walker BJ, Leys CM, Ostlie DJ, Aguayo P, Fraser JD, Alemayehu H, Peter SDS. Epidural versus PCA Pain Management after Pectus Excavatum Repair: A Multi-Institutional Prospective Randomized Trial. Eur J Pediatr Surg. 2020 Oct;30(5):465-471
Aiken TJ, Stahl CC, Lemaster D, Casias TW, Walker BJ, Nichol PF, Leys CM, Abbott DE, Brinkman AS. Intercostal nerve cryoablation is associated with lower hospital cost during minimally invasive Nuss procedure for pectus excavatum.J Pediatr Surg. 2021 Oct;56(10):1841-18
Tamai RJ, Sullivan BT, Lee RJ. Residual Neurological Symptoms After Peripheral Nerve Blocks for Pediatric Knee Surgery.J Pediatr Orthop. 2018 Mar;38(3):e157-e16
Kovacic U, Sketelj J, Bajrović FF: Age-related differences in the reinnervation after peripheral nerve injury. Int Rev Neurobiol 2009; 87:465–82
Chemnitz A, Björkman A, Dahlin LB, Rosén B:Functional outcome thirty years after median and ulnar nerve repair in childhood and adolescence. J Bone Joint Surg Am 2013; 95:329–37 1
Luo R, Tong X, Yan W, Liu H, Yang L, Zuo Y. Effects of erector spinae plane block on postoperative pain in children undergoing surgery: A systematic review and meta-analysis of randomized controlled trials. Paediatr Anaesth. 2021 Oct;31(10):1046-1055. doi: 10.1111/pan.14255. Epub 2021 Aug 2. PMID: 34270146.
Lonnqvist PA, Karmakar MK, Richardson J, Moriggl B. Daring discourse: should the ESP block be renamed RIP II block? Reg Anesth Pain Med. 2021 Jan;46(1):57-60.