May 19, 2023
The National Center for Health Research (NCHR) appreciates the opportunity to submit public comments on the Agency for Healthcare Research and Quality Systematic Review of Peripheral Nerve Blocks (PNB) for Postoperative Pain Management.
NCHR is a non-profit think tank that conducts, analyzes, and scrutinizes research on a range of health issues, with particular focus on which prevention strategies and treatments are most effective for which patients and consumers. We do not accept funding from companies that make products that are the subject of our work, so we have no conflicts of interest.
It is imperative to address the root causes of pain and opportunities to safely prevent and treat it. Helping patients avoid opioids in the postoperative period may prevent pain conversion from acute to chronic pain, and also avoid opioid addiction. In order to achieve these two goals, opioid-sparing pain medications must be safe and effective in the postoperative period. Peripheral nerve blocks (PNB) have the potential to reduce perioperative opioid use and its associated adverse effects.
Research has shown that PNB improve pain control and reduce opioid requirements compared with opioids alone.1,2 Meta-analyses of randomized controlled trials demonstrated superior pain control and reductions in opioid consumption in patients receiving PNB compared with those receiving intravenous opioids in a variety of upper and lower extremity surgical procedures.1 One major limitation is that the majority of the research literature investigates short term (up to 72 hours post operation). Additionally, the benefit of PNB over opioids may not apply across all procedures. For example, the impact of PNB on pain intensity in patients undergoing ACL repair is not clear. In one study comparing PNB in combination with systemic analgesia to systemic analgesia alone, pain intensities at rest and on movement were not significantly improved in patients undergoing ACL repair receiving PNB.3
When evaluating the outcomes of PNB use across clinical and demographic characteristics, the benefits appear consistent. A population-based, retrospective cohort study looking at the effectiveness of PNB for hip fracture surgery across over 10,000 blocks found that PNB improved population-level health system outcomes for hip fracture surgery patients.4 All adjusted regression models accounted for demographic groups including age (all patients 66+), sex, income, hospital setting, location (rural vs. non-rural), and numerous comorbidities. There were non-substantial differences between exposure groups except for a smaller proportion of patients who received a PNB lived in a rural residence.4 No significant differences were found between the use of a peripheral nerve block and chronic obstructive pulmonary disease, sex, history of dementia, or trauma admission.
While PNB have been shown to more effectively limit pain compared to opioids alone in certain procedures, there are some significant risks. These risks include vascular puncture and bleeding, nerve damage, and local anesthetic systemic toxicity (LAST) which can occur regardless of the technique or the location of the PNB. Neurological complications are important to note, as they can last weeks to months post-op.5 One study of 1010 consecutive blocks reported these complications to be as high as 8.2% at day 10. However, the incidence significantly and dramatically decreased after six months of follow up (0.6%).6 Continuous PNB (cPNB) may be complicated by catheter obstruction, migration, and leakage of local anesthetic as well as accidental removal of catheters. The risk of catheter complications is low but could lead to infections or inflammation.
Signs and symptoms of LAST are dose dependent and include symptoms such as metallic taste, tinnitus, mouth numbness, seizure, cardiac arrest, and death.7 LAST mortality has been estimated to occur in 0.023 cases/100,000.8 Registry-based studies have reported seizure incidence of 0.08-0.28 per 1000 blocks for single PNB (sPNB), whereas studies evaluating exclusively cPNB have found no evidence of seizure risk.9,10 LAST without seizure is reported to be from 0.25%-0.9% in patients receiving cPNB.8
Another possible risk of a PNB in the lower extremities is a negative impact on ambulation. A systemic review of 258 articles for total knee arthroplasty or total hip arthroplasty suggested that use of a PNB increased the risk for falls and difficulty ambulation through postoperative day two in patients after lower extremity surgery.11
1. Joshi, G., Gandhi, K., Shah, N., Gadsden, J., & Corman, S. L. (2016). Peripheral nerve blocks in the management of postoperative pain: challenges and opportunities. Journal of clinical anesthesia, 35, 524–529. https://doi.org/10.1016/j.jclinane.2016.08.041
2. Chan et al. (2014). Femoral nerve blocks for acute postoperative pain after knee replacement surgery. Cochrane Library. https://doi.org/10.1002/14651858.CD009941.pub2
3. Xu et al. (2014). Peripheral nerve blocks for postoperative pain after major knee surgery. Cochrane Library. https://doi.org/10.1002/14651858.CD010937.pub2
4. Hamilton, G., Lalu, M., Ramlogan, R., et al. (2019). A Population-based Comparative Effectiveness Study of Peripheral Nerve Blocks for Hip Fracture Surgery. Anesthesiology; 131:1025–1035 doi: https://doi.org/10.1097/ALN.0000000000002947
5. Widmer, B. et al. (2013). Incidence and severity of complications due to femoral nerve blocks performed for knee surgery. The Knee. https://doi.org/10.1016/j.knee.2012.11.002
6. Fredrickson, M.J. & Kilfoyle, D.H. (2009). Neurological complication analysis of 1000 ultrasound guided peripheral nerve blocks for elective orthopaedic surgery: a prospective study. Anaesthesia, 64: 836-844. https://doi.org/10.1111/j.1365-2044.2009.05938.x
7. Morau, D., & Ahern, S. (2010). Management of Local Anesthetic Toxicity. International Anesthesiology Clinics 48(4):p 117-140, Fall 2010. | DOI: 10.1097/AIA.0b013e3181faa464
8. Mather, L., Copeland, S., Ladd, L. (2005). Acute Toxicity of Local Anesthetics: Underlying Pharmacokinetic and Pharmacodynamic Concepts. Reg Anesth Pain Med;30:553-66.
9. Sites, B. D., Taenzer, A. H., Herrick, M. D., Gilloon, C., Antonakakis, J., Richins, J., & Beach, M. L. (2012). Incidence of local anesthetic systemic toxicity and postoperative neurologic symptoms associated with 12,668 ultrasound-guided nerve blocks: an analysis from a prospective clinical registry. Regional anesthesia and pain medicine, 37(5), 478–482. https://doi.org/10.1097/AAP.0b013e31825cb3d6
10. Compère, V., Rey, N., Baert, O., Ouennich, A., Fourdrinier, V., Roussignol, X., Beccari, R., & Dureuil, B. (2009). Major complications after 400 continuous popliteal sciatic nerve blocks for post-operative analgesia. Acta anaesthesiologica Scandinavica, 53(3), 339–345. https://doi.org/10.1111/j.1399-6576.2008.01849.x
11. Crumley Aybar, B. L., Gillespie, M. J., Gipson, S. F., Mullaney, C. E., & Tommasino-Storz, M. (2016). Peripheral Nerve Blocks Causing Increased Risk for Fall and Difficulty in Ambulation for the Hip and Knee Joint Replacement Patient. Journal of perianesthesia nursing : official journal of the American Society of PeriAnesthesia Nurses, 31(6), 504–519. https://doi.org/10.1016/j.jopan.2015.01.017