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 towardlocation 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
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.
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.
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.
LipidRescue Resuscitation: 20% Lipid Emulsion for Rescue From Drug Toxicity. http://lipidrescue.org/. Reviewed December 18, 2019. Accessed December 18, 2019.
Naropin (Ropivacaine HCL) Injection. https://www.accessdata.fda.gov/drugsatfda_docs/label/2010/020533s020s021lbl.pdf. Reviewed December 18, 2019. Accessed December 18, 2019.
Tran DQ et al: Lower extremity regional anesthesia: essentials of our current understanding. Reg Anesth Pain Med. ePub, 2019
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
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
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
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.
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
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
DeAngelis GA et al: Bleeding risk and management in interventional procedures in chronic liver disease. J Vasc Interv Radiol. 27(11):1665-74, 2016
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
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
Hamilton RJ: Tarascon Pharmacopoeia 2016: Desk Reference Edition. Place of publication not identified: Jones & Bartlett Learning, 2015
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
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
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
Vadhanan P et al: Physiological and pharmacologic aspects of peripheral nerve blocks. J Anaesthesiol Clin Pharmacol. 31(3):384-93, 2015
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
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
Olsen JW et al: Moderate sedation: what radiologists need to know. AJR Am J Roentgenol. 201(5):941-6, 2013
Albanese G et al: Pharmacology of sclerotherapy. Semin Intervent Radiol. 27(4):391-9, 2010
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
Pavlidakey PG et al: Diphenhydramine as an alternative local anesthetic agent. J Clin Aesthet Dermatol. 2(10):37-40, 2009
Hatsiopoulou O et al: Postprocedure pain management of interventional radiology patients. J Vasc Interv Radiol. 14(11):1373-85, 2003
Martin ML et al: Sedation and analgesia in the interventional radiology department. J Vasc Interv Radiol. 14(9 Pt 1):1119-28, 2003
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
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 towardlocation 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
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.
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.
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.
LipidRescue Resuscitation: 20% Lipid Emulsion for Rescue From Drug Toxicity. http://lipidrescue.org/. Reviewed December 18, 2019. Accessed December 18, 2019.
Naropin (Ropivacaine HCL) Injection. https://www.accessdata.fda.gov/drugsatfda_docs/label/2010/020533s020s021lbl.pdf. Reviewed December 18, 2019. Accessed December 18, 2019.
Tran DQ et al: Lower extremity regional anesthesia: essentials of our current understanding. Reg Anesth Pain Med. ePub, 2019
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
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
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
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.
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
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
DeAngelis GA et al: Bleeding risk and management in interventional procedures in chronic liver disease. J Vasc Interv Radiol. 27(11):1665-74, 2016
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
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
Hamilton RJ: Tarascon Pharmacopoeia 2016: Desk Reference Edition. Place of publication not identified: Jones & Bartlett Learning, 2015
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
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
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
Vadhanan P et al: Physiological and pharmacologic aspects of peripheral nerve blocks. J Anaesthesiol Clin Pharmacol. 31(3):384-93, 2015
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
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
Olsen JW et al: Moderate sedation: what radiologists need to know. AJR Am J Roentgenol. 201(5):941-6, 2013
Albanese G et al: Pharmacology of sclerotherapy. Semin Intervent Radiol. 27(4):391-9, 2010
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
Pavlidakey PG et al: Diphenhydramine as an alternative local anesthetic agent. J Clin Aesthet Dermatol. 2(10):37-40, 2009
Hatsiopoulou O et al: Postprocedure pain management of interventional radiology patients. J Vasc Interv Radiol. 14(11):1373-85, 2003
Martin ML et al: Sedation and analgesia in the interventional radiology department. J Vasc Interv Radiol. 14(9 Pt 1):1119-28, 2003
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
Fujii S et al: [Lipid metabolism and cyclic AMP.] Rinsho Byori. 20(11):798-804, 1972
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