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Peripheral Nerve Blocks
Rafael Vazquez, MD
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KEY FACTS

  • Terminology

    • Preprocedure

      • Procedure

        • Post Procedure

          TERMINOLOGY

          • Abbreviations

            • Peripheral nerve block (PNB)
            • Local anesthetic (LA)
            • Local anesthetic systemic toxicity (LAST)
          • Synonyms

            • Nerve blocks
            • Regional nerve block
            • Regional block
            • Regional anesthesia
          • Definitions

            • PNB: Temporary blockade of peripheral neural conduction to achieve analgesia &/or anesthesia
            • LA: Class of medications that temporarily abolish neural conduction, and, when used peripherally, they block sensory (nociception) and motor function
              • Due to different physical properties of peripheral sensory (nociceptors) and motor neurons, with sensory nerves that transduce pain being primarily unmyelinated vs. motor neurons that are myelinated, onset and duration of blockade differs depending on volume and concentration of LA, with former being blocked 1st and recovering 1st, whereas latter is blocked later and blockade resolves later
              • Duration of LA also depends on site of injection
                • Highly vascular regions will tend to "wash out" LA when compared to avascular regions
            • LA adjuncts: Medications whose primary indication is not for nerve block but utilized to synergize duration of LA
            • Peripheral nerve catheter: Catheter that is placed near nerves or intrafascial planes to provide more prolonged analgesia than that of single-shot nerve block
            • Procedural nerve block anesthesia: Dense nerve block that results in loss of motor and sensory function such that there is no sensation to procedural stimulus
              • Achieved with concentrated LA and high LA volume
            • Procedural nerve block analgesia: Blockade of sensory nociceptors that only spares motor function; its primary use is for nociceptive pain blockade only
              • Achieved with less concentrated LA
            • LAST: When blood levels of LA become supratherapeutic, there is adverse effect of CNS, initially characterized by tinnitus, metallic taste in mouth, escalating to seizures, and eventually to cardiovascular collapse; it is treated with lipid emulsion
            • Lipid emulsion (Intralipid) 20%: Lipid-based medication that binds to LA in bloodstream and renders drug inactive; it acts as vacuum and is utilized as rescue medication for LAST; it is administered initially as bolus and then as infusion
          • Clinical Implications

            • Regional nerve blocks
              • Medications
                • LA
                • Neurolytic agents
                • Contrast
                • Adjuvants, such as steroids and epinephrine
            • Targets
              • Discrete nerves
              • Nerve plexuses (branching network of intersecting nerves)
              • Discrete interfascial planes
              • Potential spaces
            • 2 techniques can be used to perform PNB
              • Nonimage guided
                • Paraesthesia technique
                  • Nerves are identified by guiding needle "blindly" toward typical anatomical location of nerves until eliciting paresthesias and injection of LA
                • Nerve stimulation
                  • Specialized needle that conducts small electrical current is guided toward nerves until motor or sensory response is elicited
              • Image guidance
                • Ultrasound: Enables relatively rapid identification of neurovascular structures with subsequent real-time in-plane guidance of needle toward these structures
                  • Needle can be precisely guided, and LA spread can be seen
                  • Requires thorough knowledge of sonoanatomy of neurovascular regions
                  • Visualization can be challenging, as image quality is dependent on ultrasound capabilities, transducer placement, and patient factors, such as body habitus
                  • Excellent hand-eye coordination is essential for in-plane guidance of needle
                • Fluoroscopy: Can precisely guide block needle within bony structures and regions of body
                  • Needle is guided blindly toward anatomical landmarks
                  • Requires contrast and radiation to confirm placement
                  • Imaging quality is independent of patient body habitus
                  • In some instances, it can be faster than ultrasound, especially with patient with challenging body habitus (morbidly obese)
                • CT: Can precisely guide block needle toward location of neural structure(s) in stepwise fashion, navigating through and around body structures
                  • Excellent for deep nerve blocks at discrete anatomical locations (obturator nerve within obturator groove in pelvis) and fascial plane blocks
                  • Excellent imaging of body structures independent of patient body habitus
                  • Difficult to identify discrete nerves and assess LA spread
                  • Requires contrast and radiation to confirm placement
                  • Relatively time consuming
                • Magnetic resonance (MR) imaging: Can precisely guide needle toward neural structure(s) with subsequent visualization of LA spread within or adjacent to nerve(s)
                  • High-fidelity visualization of deep nerves and anatomy irrespective of patient body habitus
                  • No contrast or radiation utilized
                  • Expensive and relatively time consuming

          PREPROCEDURE

          • Indications

            • Contraindications

              • Preprocedure Imaging

                • Getting Started

                  • General Safety Guidelines for Regional Nerve Blocks

                    • Anticoagulant/Antiplatelet

                      PROCEDURE

                      • Patient Position/Location

                        • Equipment Preparation

                          • Procedure Steps

                            • Findings and Reporting

                              • Alternative Procedures/Therapies

                                POST PROCEDURE

                                • Expected Outcome

                                  • Things To Do

                                    • Things To Avoid

                                      OUTCOMES

                                      • Problems

                                        • Complications

                                          Selected References

                                          1. American Association of Blood Banks Circular of Information for the Use of Human Blood and Blood Components. http://www.aabb.org/tm/coi/Documents/coi1113.pdf. Reviewed December 18, 2019. Accessed December 18, 2019.
                                          2. American College of Radiology Manual on Contrast Media. https://www.acr.org/-/media/ACR/Files/Clinical-Resources/Contrast_Media.pdf. Reviewed December 18, 2019. Accessed December 18, 2019.
                                          3. American Society of Regional Anesthesia and Pain Medicine: Checklist for treatment of local anesthetic systemic toxicity. https://www.asra.com/advisory-guidelines/article/3/checklist-for-treatment-of-local-anesthetic-systemic-toxicity. Reviewed December 18, 2019. Accessed December 18, 2019.
                                          4. LipidRescue Resuscitation: 20% Lipid Emulsion for Rescue From Drug Toxicity. http://lipidrescue.org/. Reviewed December 18, 2019. Accessed December 18, 2019.
                                          5. Naropin (Ropivacaine HCL) Injection. https://www.accessdata.fda.gov/drugsatfda_docs/label/2010/020533s020s021lbl.pdf. Reviewed December 18, 2019. Accessed December 18, 2019.
                                          6. Tran DQ et al: Lower extremity regional anesthesia: essentials of our current understanding. Reg Anesth Pain Med. ePub, 2019
                                          7. Horlocker TT et al: Regional anesthesia in the patient receiving antithrombotic or thrombolytic therapy: American Society of Regional Anesthesia and Pain Medicine evidence-based guidelines (fourth edition). Reg Anesth Pain Med. 43(3):263-309, 2018
                                          8. Narouze S et al: Interventional spine and pain procedures in patients on antiplatelet and anticoagulant medications (second edition): guidelines from the American Society of Regional Anesthesia and Pain Medicine, the European Society of Regional Anaesthesia and Pain Therapy, the American Academy of Pain Medicine, the International Neuromodulation Society, the North American Neuromodulation Society, and the World Institute of Pain. Reg Anesth Pain Med. 43(3):225-62, 2018
                                          9. Rubin DS et al: Local anesthetic systemic toxicity in total joint arthroplasty: incidence and risk factors in the United States from the National Inpatient Sample 1998-2013. Reg Anesth Pain Med. 43(2):131-7, 2018
                                          10. American College of Radiology Manual on Contrast Media. V10.2 https://www.acr.org/quality-safety/resources/contrast-manual. Reviewed March 28, 2017. Accessed March 28, 2017.
                                          11. Ilfeld BM: Continuous peripheral nerve blocks: an update of the published evidence and comparison with novel, alternative analgesic modalities. Anesth Analg. 124(1):308-35, 2017
                                          12. Chou R et al: Management of postoperative pain: a clinical practice guideline from the American Pain Society, the American Society of Regional Anesthesia and Pain Medicine, and the American Society of Anesthesiologists' Committee on Regional Anesthesia, executive committee, and administrative council. J Pain. 17(2):131-57, 2016
                                          13. DeAngelis GA et al: Bleeding risk and management in interventional procedures in chronic liver disease. J Vasc Interv Radiol. 27(11):1665-74, 2016
                                          14. Neal JM et al: The second American Society of Regional Anesthesia and Pain Medicine evidence-based medicine assessment of ultrasound-guided regional anesthesia: executive summary. Reg Anesth Pain Med. 41(2):181-94, 2016
                                          15. Saporito A et al: Can the choice of the local anesthetic have an impact on ambulatory surgery perioperative costs? Chloroprocaine for popliteal block in outpatient foot surgery. J Clin Anesth. 32:119-26, 2016
                                          16. Hamilton RJ: Tarascon Pharmacopoeia 2016: Desk Reference Edition. Place of publication not identified: Jones & Bartlett Learning, 2015
                                          17. Kaur A et al: Comparision between bupivacaine and ropivacaine in patients undergoing forearm surgeries under axillary brachial plexus block: a prospective randomized study. J Clin Diagn Res. 9(1):UC01-6, 2015
                                          18. Neal JM et al: The second ASRA practice advisory on neurologic complications associated with regional anesthesia and pain medicine: executive summary 2015. Reg Anesth Pain Med. 40(5):401-30, 2015
                                          19. Ul Haq F et al: Bleomycin foam treatment of venous malformations: a promising agent for effective treatment with minimal swelling. J Vasc Interv Radiol. 26(10):1484-93, 2015
                                          20. Vadhanan P et al: Physiological and pharmacologic aspects of peripheral nerve blocks. J Anaesthesiol Clin Pharmacol. 31(3):384-93, 2015
                                          21. Fritz J et al: Magnetic resonance neurography-guided nerve blocks for the diagnosis and treatment of chronic pelvic pain syndrome. Neuroimaging Clin N Am. 24(1):211-34, 2014
                                          22. Lawson EF et al: Neurolytic agents. In Deer TR. et al. Treatment of Chronic Pain by Interventional Approaches: The American Academy of Pain Medicine Textbook on Patient Management. New York, NY: Springer, 2014
                                          23. Olsen JW et al: Moderate sedation: what radiologists need to know. AJR Am J Roentgenol. 201(5):941-6, 2013
                                          24. Albanese G et al: Pharmacology of sclerotherapy. Semin Intervent Radiol. 27(4):391-9, 2010
                                          25. Venkatesan AM et al: Practice guidelines for adult antibiotic prophylaxis during vascular and interventional radiology procedures. Written by the Standards of Practice Committee for the Society of Interventional Radiology and Endorsed by the Cardiovascular Interventional Radiological Society of Europe and Canadian Interventional Radiology Association [corrected]. J Vasc Interv Radiol. 21(11):1611-30; quiz 1631, 2010
                                          26. Pavlidakey PG et al: Diphenhydramine as an alternative local anesthetic agent. J Clin Aesthet Dermatol. 2(10):37-40, 2009
                                          27. Hatsiopoulou O et al: Postprocedure pain management of interventional radiology patients. J Vasc Interv Radiol. 14(11):1373-85, 2003
                                          28. Martin ML et al: Sedation and analgesia in the interventional radiology department. J Vasc Interv Radiol. 14(9 Pt 1):1119-28, 2003
                                          29. Hofmann-Kiefer K et al: Ropivacaine 7.5 mg/ml versus bupivacaine 5 mg/ml for interscalene brachial plexus block--a comparative study. Anaesth Intensive Care. 30(3):331-7, 2002
                                          30. Fujii S et al: [Lipid metabolism and cyclic AMP.] Rinsho Byori. 20(11):798-804, 1972
                                          Related Anatomy
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                                          Related Differential Diagnoses
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                                          References
                                          Tables

                                          Tables

                                          KEY FACTS

                                          • Terminology

                                            • Preprocedure

                                              • Procedure

                                                • Post Procedure

                                                  TERMINOLOGY

                                                  • Abbreviations

                                                    • Peripheral nerve block (PNB)
                                                    • Local anesthetic (LA)
                                                    • Local anesthetic systemic toxicity (LAST)
                                                  • Synonyms

                                                    • Nerve blocks
                                                    • Regional nerve block
                                                    • Regional block
                                                    • Regional anesthesia
                                                  • Definitions

                                                    • PNB: Temporary blockade of peripheral neural conduction to achieve analgesia &/or anesthesia
                                                    • LA: Class of medications that temporarily abolish neural conduction, and, when used peripherally, they block sensory (nociception) and motor function
                                                      • Due to different physical properties of peripheral sensory (nociceptors) and motor neurons, with sensory nerves that transduce pain being primarily unmyelinated vs. motor neurons that are myelinated, onset and duration of blockade differs depending on volume and concentration of LA, with former being blocked 1st and recovering 1st, whereas latter is blocked later and blockade resolves later
                                                      • Duration of LA also depends on site of injection
                                                        • Highly vascular regions will tend to "wash out" LA when compared to avascular regions
                                                    • LA adjuncts: Medications whose primary indication is not for nerve block but utilized to synergize duration of LA
                                                    • Peripheral nerve catheter: Catheter that is placed near nerves or intrafascial planes to provide more prolonged analgesia than that of single-shot nerve block
                                                    • Procedural nerve block anesthesia: Dense nerve block that results in loss of motor and sensory function such that there is no sensation to procedural stimulus
                                                      • Achieved with concentrated LA and high LA volume
                                                    • Procedural nerve block analgesia: Blockade of sensory nociceptors that only spares motor function; its primary use is for nociceptive pain blockade only
                                                      • Achieved with less concentrated LA
                                                    • LAST: When blood levels of LA become supratherapeutic, there is adverse effect of CNS, initially characterized by tinnitus, metallic taste in mouth, escalating to seizures, and eventually to cardiovascular collapse; it is treated with lipid emulsion
                                                    • Lipid emulsion (Intralipid) 20%: Lipid-based medication that binds to LA in bloodstream and renders drug inactive; it acts as vacuum and is utilized as rescue medication for LAST; it is administered initially as bolus and then as infusion
                                                  • Clinical Implications

                                                    • Regional nerve blocks
                                                      • Medications
                                                        • LA
                                                        • Neurolytic agents
                                                        • Contrast
                                                        • Adjuvants, such as steroids and epinephrine
                                                    • Targets
                                                      • Discrete nerves
                                                      • Nerve plexuses (branching network of intersecting nerves)
                                                      • Discrete interfascial planes
                                                      • Potential spaces
                                                    • 2 techniques can be used to perform PNB
                                                      • Nonimage guided
                                                        • Paraesthesia technique
                                                          • Nerves are identified by guiding needle "blindly" toward typical anatomical location of nerves until eliciting paresthesias and injection of LA
                                                        • Nerve stimulation
                                                          • Specialized needle that conducts small electrical current is guided toward nerves until motor or sensory response is elicited
                                                      • Image guidance
                                                        • Ultrasound: Enables relatively rapid identification of neurovascular structures with subsequent real-time in-plane guidance of needle toward these structures
                                                          • Needle can be precisely guided, and LA spread can be seen
                                                          • Requires thorough knowledge of sonoanatomy of neurovascular regions
                                                          • Visualization can be challenging, as image quality is dependent on ultrasound capabilities, transducer placement, and patient factors, such as body habitus
                                                          • Excellent hand-eye coordination is essential for in-plane guidance of needle
                                                        • Fluoroscopy: Can precisely guide block needle within bony structures and regions of body
                                                          • Needle is guided blindly toward anatomical landmarks
                                                          • Requires contrast and radiation to confirm placement
                                                          • Imaging quality is independent of patient body habitus
                                                          • In some instances, it can be faster than ultrasound, especially with patient with challenging body habitus (morbidly obese)
                                                        • CT: Can precisely guide block needle toward location of neural structure(s) in stepwise fashion, navigating through and around body structures
                                                          • Excellent for deep nerve blocks at discrete anatomical locations (obturator nerve within obturator groove in pelvis) and fascial plane blocks
                                                          • Excellent imaging of body structures independent of patient body habitus
                                                          • Difficult to identify discrete nerves and assess LA spread
                                                          • Requires contrast and radiation to confirm placement
                                                          • Relatively time consuming
                                                        • Magnetic resonance (MR) imaging: Can precisely guide needle toward neural structure(s) with subsequent visualization of LA spread within or adjacent to nerve(s)
                                                          • High-fidelity visualization of deep nerves and anatomy irrespective of patient body habitus
                                                          • No contrast or radiation utilized
                                                          • Expensive and relatively time consuming

                                                  PREPROCEDURE

                                                  • Indications

                                                    • Contraindications

                                                      • Preprocedure Imaging

                                                        • Getting Started

                                                          • General Safety Guidelines for Regional Nerve Blocks

                                                            • Anticoagulant/Antiplatelet

                                                              PROCEDURE

                                                              • Patient Position/Location

                                                                • Equipment Preparation

                                                                  • Procedure Steps

                                                                    • Findings and Reporting

                                                                      • Alternative Procedures/Therapies

                                                                        POST PROCEDURE

                                                                        • Expected Outcome

                                                                          • Things To Do

                                                                            • Things To Avoid

                                                                              OUTCOMES

                                                                              • Problems

                                                                                • Complications

                                                                                  Selected References

                                                                                  1. American Association of Blood Banks Circular of Information for the Use of Human Blood and Blood Components. http://www.aabb.org/tm/coi/Documents/coi1113.pdf. Reviewed December 18, 2019. Accessed December 18, 2019.
                                                                                  2. American College of Radiology Manual on Contrast Media. https://www.acr.org/-/media/ACR/Files/Clinical-Resources/Contrast_Media.pdf. Reviewed December 18, 2019. Accessed December 18, 2019.
                                                                                  3. American Society of Regional Anesthesia and Pain Medicine: Checklist for treatment of local anesthetic systemic toxicity. https://www.asra.com/advisory-guidelines/article/3/checklist-for-treatment-of-local-anesthetic-systemic-toxicity. Reviewed December 18, 2019. Accessed December 18, 2019.
                                                                                  4. LipidRescue Resuscitation: 20% Lipid Emulsion for Rescue From Drug Toxicity. http://lipidrescue.org/. Reviewed December 18, 2019. Accessed December 18, 2019.
                                                                                  5. Naropin (Ropivacaine HCL) Injection. https://www.accessdata.fda.gov/drugsatfda_docs/label/2010/020533s020s021lbl.pdf. Reviewed December 18, 2019. Accessed December 18, 2019.
                                                                                  6. Tran DQ et al: Lower extremity regional anesthesia: essentials of our current understanding. Reg Anesth Pain Med. ePub, 2019
                                                                                  7. Horlocker TT et al: Regional anesthesia in the patient receiving antithrombotic or thrombolytic therapy: American Society of Regional Anesthesia and Pain Medicine evidence-based guidelines (fourth edition). Reg Anesth Pain Med. 43(3):263-309, 2018
                                                                                  8. Narouze S et al: Interventional spine and pain procedures in patients on antiplatelet and anticoagulant medications (second edition): guidelines from the American Society of Regional Anesthesia and Pain Medicine, the European Society of Regional Anaesthesia and Pain Therapy, the American Academy of Pain Medicine, the International Neuromodulation Society, the North American Neuromodulation Society, and the World Institute of Pain. Reg Anesth Pain Med. 43(3):225-62, 2018
                                                                                  9. Rubin DS et al: Local anesthetic systemic toxicity in total joint arthroplasty: incidence and risk factors in the United States from the National Inpatient Sample 1998-2013. Reg Anesth Pain Med. 43(2):131-7, 2018
                                                                                  10. American College of Radiology Manual on Contrast Media. V10.2 https://www.acr.org/quality-safety/resources/contrast-manual. Reviewed March 28, 2017. Accessed March 28, 2017.
                                                                                  11. Ilfeld BM: Continuous peripheral nerve blocks: an update of the published evidence and comparison with novel, alternative analgesic modalities. Anesth Analg. 124(1):308-35, 2017
                                                                                  12. Chou R et al: Management of postoperative pain: a clinical practice guideline from the American Pain Society, the American Society of Regional Anesthesia and Pain Medicine, and the American Society of Anesthesiologists' Committee on Regional Anesthesia, executive committee, and administrative council. J Pain. 17(2):131-57, 2016
                                                                                  13. DeAngelis GA et al: Bleeding risk and management in interventional procedures in chronic liver disease. J Vasc Interv Radiol. 27(11):1665-74, 2016
                                                                                  14. Neal JM et al: The second American Society of Regional Anesthesia and Pain Medicine evidence-based medicine assessment of ultrasound-guided regional anesthesia: executive summary. Reg Anesth Pain Med. 41(2):181-94, 2016
                                                                                  15. Saporito A et al: Can the choice of the local anesthetic have an impact on ambulatory surgery perioperative costs? Chloroprocaine for popliteal block in outpatient foot surgery. J Clin Anesth. 32:119-26, 2016
                                                                                  16. Hamilton RJ: Tarascon Pharmacopoeia 2016: Desk Reference Edition. Place of publication not identified: Jones & Bartlett Learning, 2015
                                                                                  17. Kaur A et al: Comparision between bupivacaine and ropivacaine in patients undergoing forearm surgeries under axillary brachial plexus block: a prospective randomized study. J Clin Diagn Res. 9(1):UC01-6, 2015
                                                                                  18. Neal JM et al: The second ASRA practice advisory on neurologic complications associated with regional anesthesia and pain medicine: executive summary 2015. Reg Anesth Pain Med. 40(5):401-30, 2015
                                                                                  19. Ul Haq F et al: Bleomycin foam treatment of venous malformations: a promising agent for effective treatment with minimal swelling. J Vasc Interv Radiol. 26(10):1484-93, 2015
                                                                                  20. Vadhanan P et al: Physiological and pharmacologic aspects of peripheral nerve blocks. J Anaesthesiol Clin Pharmacol. 31(3):384-93, 2015
                                                                                  21. Fritz J et al: Magnetic resonance neurography-guided nerve blocks for the diagnosis and treatment of chronic pelvic pain syndrome. Neuroimaging Clin N Am. 24(1):211-34, 2014
                                                                                  22. Lawson EF et al: Neurolytic agents. In Deer TR. et al. Treatment of Chronic Pain by Interventional Approaches: The American Academy of Pain Medicine Textbook on Patient Management. New York, NY: Springer, 2014
                                                                                  23. Olsen JW et al: Moderate sedation: what radiologists need to know. AJR Am J Roentgenol. 201(5):941-6, 2013
                                                                                  24. Albanese G et al: Pharmacology of sclerotherapy. Semin Intervent Radiol. 27(4):391-9, 2010
                                                                                  25. Venkatesan AM et al: Practice guidelines for adult antibiotic prophylaxis during vascular and interventional radiology procedures. Written by the Standards of Practice Committee for the Society of Interventional Radiology and Endorsed by the Cardiovascular Interventional Radiological Society of Europe and Canadian Interventional Radiology Association [corrected]. J Vasc Interv Radiol. 21(11):1611-30; quiz 1631, 2010
                                                                                  26. Pavlidakey PG et al: Diphenhydramine as an alternative local anesthetic agent. J Clin Aesthet Dermatol. 2(10):37-40, 2009
                                                                                  27. Hatsiopoulou O et al: Postprocedure pain management of interventional radiology patients. J Vasc Interv Radiol. 14(11):1373-85, 2003
                                                                                  28. Martin ML et al: Sedation and analgesia in the interventional radiology department. J Vasc Interv Radiol. 14(9 Pt 1):1119-28, 2003
                                                                                  29. Hofmann-Kiefer K et al: Ropivacaine 7.5 mg/ml versus bupivacaine 5 mg/ml for interscalene brachial plexus block--a comparative study. Anaesth Intensive Care. 30(3):331-7, 2002
                                                                                  30. Fujii S et al: [Lipid metabolism and cyclic AMP.] Rinsho Byori. 20(11):798-804, 1972