Continuous Peripheral Nerve Block: Uses and Risks
First described in 1946 1, a continuous peripheral nerve block (CPNB) consists of a percutaneously inserted catheter administering a local anesthetic adjacent to a target nerve or plexus. Using currently available long-acting local anesthetics, a single-injection peripheral nerve block does not last longer than 24 hours. In contrast, CPNB provides a substantially prolonged neural blockade, lasting days or months, that may be titrated according to the desired effect 2,3.
Having evolved from its rudimentary form as a needle inserted through a cork taped to a patient’s chest all the way to its current status as a well-validated, advanced analgesic method, CPNBs enable a slew of precisely tailored applications spanning in-hospital and ambulatory settings. This technique’s most common application is to provide analgesia during surgical procedures 4; consistently, perioperative pain relief is the only application of CPNBs that has been confirmed by randomized controlled clinical trials 5. CPNBs can also provide post-traumatic pain relief (such as following a bone fracture), deliver analgesia during patient transportation to a distant treatment center (while simply awaiting surgical repair), or to abate abdominal wall pain during pregnancy. CPNBs can also treat chronic pain, such as in the form of complex regional pain syndrome, terminal cancer-related pain, phantom limb pain, or trigeminal neuralgia. Additional specific, non-pain-associated uses have included treating intractable hiccups 6, inducing vasodilation to increase blood flow following a vascular accident 7, digit replantation 8, and limb salvage 9. Finally, a continuous peripheral nerve block can be used to alleviate Raynaud-associated vasospasm 10 and treat peripheral embolism 11.
CPNBs have many wide-ranging benefits 12. Documented outcomes are dependent on their ability to provide analgesia and include decreasing baseline pain levels, reducing opioid-related side effects, and treating sleep disturbances. In some cases, patient satisfaction and physical function may be improved, alongside an accelerated resumption of passive joint range-of-motion; accordingly, patient discharge from the hospital or rehabilitation center may also be accelerated. Finally, postoperative joint inflammation and inflammatory markers may be decreased.
Complications occur somewhat frequently with CPNBs, though most are minor. First, the CPNB may fail: various prospective studies report an incidence of secondary infusion failure ranging from 1-50%. Errors during catheter insertion include catheter tip placement too far from the target nerve to provide postoperative analgesia, post-insertion catheter migration, and epidural, intrathecal, intravascular, intraneural, and interpleural insertion in rare scenarios. During infusion, complications can include catheter obstruction, fluid leakage, or pump dysfunction or disconnection 12.
In contrast, major complications remain relatively rare. Nerve injury remains a rare side effect13. Associated complications may include prolonged Horner syndrome resulting from an interruption of the sympathetic nervous system to the eye, or dyspnea or lower lobe collapse following infusions potentially affecting the phrenic nerve. Peri-catheter hematoma formation has also been reported, often with concurrently administered low-molecular-weight heparin for thromboprophylaxis. Inflammation and catheter bacterial colonization rates (up to 4% and 7%, respectively) are relatively high. Clinically relevant infection, however, remains relatively rare – though life-threatening catheter-related sepsis has been reported 14. Finally, the most severe complication is local anesthetic systemic toxicity. While infrequent, this may take the form of myotoxicity/myonecrosis with repeated large boluses of bupivacaine 15,16 or various neurologic and cardiovascular symptoms, including in the form of cardiovascular collapse 17.
Given the intrinsic risks of CPNBs despite their widespread uses, most clinicians implement them only for procedures not amenable to less invasive analgesic techniques or with patients intolerant to alternative forms of analgesia. Despite heterogeneous catheter insertion techniques, equipment, and anatomical locations, specific guidelines have been developed to minimize their risk as the continuous peripheral nerve block remain core medical procedures for which deleterious side effects should be carefully considered when planning for surgery.
References
1. Ansbro FP. A method of continuous brachial plexus block. Am J Surg. 1946. doi:10.1016/0002-9610(46)90219-X
2. Carvalho B, Aleshi P, Horstman DJ, Angst MS. Effect of a preemptive femoral nerve block on cytokine release and hyperalgesia in experimentally inflamed skin of human volunteers. Reg Anesth Pain Med. 2010. doi:10.1097/AAP.0b013e3181faa107
3. Fletcher D, Martin F, Martinez V, et al. Antiinflammatory effect of peripheral nerve blocks after knee surgery: Clinical and biologic evaluation. Anesthesiology. 2008. doi:10.1097/ALN.0b013e318182c2a1
4. DeKrey JA, Schroeder CF, Buechel DR. Continuous brachial plexus block. Anesthesiology. 1969. doi:10.1097/00000542-196903000-00022
5. Richman JM, Liu SS, Courpas G, et al. Does continuous peripheral nerve block provide superior pain control to opioids? A meta-analysis. Anesth Analg. 2006. doi:10.1213/01.ANE.0000181289.09675.7D
6. Sarnoff SJ, Sarnoff LC. Prolonged peripheral nerve block by means of indwelling plastic catheter; treatment of hiccup; note on the electrical localization of peripheral nerve. Anesthesiology. 1951. doi:10.1097/00000542-195105000-00002
7. Manriquez RG, Pallares V. Continuous brachial plexus block for prolonged sympathectomy and control of pain. Anesth Analg. 1978. doi:10.1213/00000539-197801000-00029
8. Mezzatesta JP, Scott DA, Schweitzer SA, Selander DE. Continuous axillary brachial plexus block for postoperative pain relief intermittent bolus versus continuous infusion. Reg Anesth. 1997. doi:10.1016/s1098-7339(97)80012-0
9. Loland VJ, Ilfeld BM, Abrams RA, Mariano ER. Ultrasound-guided perineural catheter and local anesthetic infusion in the perioperative management of pediatric limb salvage. Paediatr Anaesth. 2009. doi:10.1111/j.1460-9592.2009.03103.x
10. Greengrass RA, Feinglass NG, Murray PM, Trigg SD. Continuous regional anesthesia before surgical peripheral sympathectomy in a patient with severe digital necrosis associated with Raynaud’s phenomenon and scleroderma. Reg Anesth Pain Med. 2003. doi:10.1016/S1098-7339(03)00186-X
11. Treatment of peripheral embolism by continuous sciatic nerve block – PubMed. https://pubmed.ncbi.nlm.nih.gov/14945218/. Accessed June 30, 2021.
12. Ilfeld BM. Continuous peripheral nerve blocks. Eur J Pain Suppl. 2011. doi:10.1016/j.eujps.2011.08.014
13. Aguirre J, Del Moral A, Cobo I, Borgeat A, Blumenthal S. The role of continuous peripheral nerve blocks. Anesthesiol Res Pract. 2012. doi:10.1155/2012/560879
14. Capdevila X, Jaber S, Pesonen P, Borgeat A, Eledjam JJ. Acute neck cellulitis and mediastinitis complicating a continuous interscalene block. Anesth Analg. 2008. doi:10.1213/ane.0b013e318161537f
15. Zink W, Bohl JRE, Hacke N, Sinner B, Martin E, Graf BM. The long term myotoxic effects of bupivacaine and ropivacaine after continuous peripheral nerve blocks. Anesth Analg. 2005. doi:10.1213/01.ANE.0000155956.59842.0A
16. Nouette-Gaulain K, Dadure C, Morau D, et al. Age-dependent bupivacaine-induced muscle toxicity during continuous peripheral nerve block in rats. Anesthesiology. 2009. doi:10.1097/ALN.0b013e3181bbc949
17. Jeng CL, Torrillo TM, Rosenblatt MA. Complications of peripheral nerve blocks. Br J Anaesth. 2010. doi:10.1093/bja/aeq273