Introduction

  • The opioid epidemic has led ED providers to investigate effective opioid-sparing pain management strategies.
  • The provision of ultrasound-guided nerve blocks (UGNBs) is endorsed by the American College of Emergency Physicians (ACEP) as a core skill for emergency physicians and a core component of a multimodal pain pathway.1
  • Current literature supports the use of UGNBs as part of "pre-procedural pain management for orthopedic reductions/splinting, complex laceration repair, abscess incision and drainage, or acute on chronic pain conditions".1
  • Ultrasound guidance has been shown to reduce time to nerve block onset and improve the quality of peripheral nerve blocks when compared to other techniques.2
  • UGNBs have been associated with improved post-surgical functional outcomes, decreased delirium, and decreased length of stay. 2

General Contraindications for Peripheral Nerve Blocks3

  • Infection at site of injection
  • Non-responsive/non-verbal patient
  • Hardware at or near planned injection site
  • Pre-existing nerve injury or peripheral neuropathy
  • Concern for development of compartment syndrome at the site of injury
  • Allergies to local anesthetics
  • Crush injury at or near the site of injection

Potential Complications of Peripheral Nerve Blocks3

  • Local anesthetic toxicity
  • Nerve injury
  • Ecchymosis
  • Hematomas

Clinical Detail

Regional Anesthetic Pharmacology

Parameter Lidocaine Lidocaine w/ epi Bupivacaine Ropivacaine Mepivacaine
MOAAnesthetics bind to sodium channels on nerve cells and prevent subsequent depolarization and further nerve impulse conduction until the anesthetic is displaced from the neuronal membrane
Max Dose (NTE)4.5 mg/kg (300 mg)7 mg/kg (500 mg)2 mg/kg (175 mg)3 mg/kg (300 mg)4 mg/kg (300 mg)
*Dose will vary with block location due to differences in vascularity, size of the nerve, and the duration of anesthesia required
Onset4-7 min4-7 min~20 min~15 min~10 min
Duration of Analgesia~2 hours~3-4 hours~6-8 hours~6-8 hours~2-3 hours
Admin• Sterile technique should be used for all nerve blocks
• Amount of local anesthetic will vary, may dilute local anesthetic 1:1 with NS to achieve required volume
Risks• Pregnancy increases neural susceptibility to local anesthetics
• Local anesthesia systemic toxicity (LAST): confusion, anxiety, headache, drowsiness, tremors, hemodynamic collapse, widened PR interval, QRS prolongation, VT, VF, hypotension, asystole
• Local nerve injury

Evidence

Review of the Evidence

Author, year Design & Sample Size Patient Population Intervention & Comparison Outcome
Beaudoin et al., 20135Randomized controlled trial (N=36)Adults ≥55 yrs w/ confirmed hip fractures AND pain score ≥5• FNB: US-guided 3-in-1 femoral nerve block w/ 25 mL bupivacaine 0.5% + morphine
• SC: NS injection + morphine		• Pain scores were lower with FNB at 15 min and at 4 hours vs SC group (4 [0-10] vs 8 [6-10])
• FNB group received less rescue opioids than the SC group (0 mg [0-6 mg] vs 5 mg [0-21 mg])
Bhoi et al., 20126Prospective observational feasibility study (N=50)Patients ≥5 yrs requiring analgesia for acute limb emergenciesBrachial plexus block: 3-5 mg/kg lidocaine 2%
Femoral and sciatic block: 3-5 mg/kg 2% lidocaine +/- 1-2 mg/kg 0.5% bupivacaine		• No patients required rescue analgesia
• Reduction in VAS pain score of 7.44 (IQR 8-10 [75%], 1-2 [25%]; p=0.0001)
• Median time to reduction of pain: 5 min (IQR 1, 15 min)
• No immediate or late complications at 3-month follow-up
Mori et al., 20197Retrospective case series (N=6)UG ulnar nerve block prior to phalangeal reduction in pediatric patients0.1-0.2 ml/kg lidocaine 1%• No patients required additional analgesia
• All patients were discharged home after completion of reduction
• No documented complications
Cisewski & Alerhand, 20198Case series (N=2)Patient 1: 4 cm 2nd degree burn
Patient 2: 2-3 cm area of cellulitis		Lateral sural cutaneous nerve (LCSN) sensory block: 5 mL lidocaine w/ epi• Onset: 7-9 min
• Peak analgesic effect: 25-29 min
• Duration: 120-150 min
• No motor deficit or adverse effects
Barton et al., 20189Case report (N=1)44 yr male with copperhead bite to left halluxFascia iliaca compartment block: 20 mL 0.25% bupivacaine• Time to pain relief: 45 min
• Duration: 8 hours
• No adverse effects, discharged 48 hours after admission
Blaivas et al., 201110RCT (N=42)Patients in the ED with shoulder dislocationsProcedural sedation/analgesia: etomidate
Interscalene brachial plexus block (ISBPB): 20-30 mL lidocaine w/ epi		• ED length of stay slower with ISBPB (100.3 +/- 28.2 vs. 177.3 +/- 37.9 min)
• Mean 1-on-1 provider time less with ISBPB (5 +/- 0.7 vs 47.1 +/- 9.8 min)
• No significant difference in patient satisfaction, pain experienced or complications (hypoxia, hypotension)
• Transient motor paralysis did occur in all patients that received ISBPB
*NS=normal saline

Common Peripheral Nerve Blocks

Block Type Uses Suggested Anesthetics Suggested Volume Clinical Pearls
Superficial cervical plexus blockEarlobe lacerations, neck abscess, central line placementLidocaine 1% w/ epi5-8 mLProvides sensory blockade without motor blockade. Sensory nerves require lower concentrations of local anesthetic.
Interscalene brachial plexus block (ISBPB)Shoulder dislocations
Proximal humerus fracture reduction		Lidocaine 1%10 mLPhrenic nerve blockade, sympathetic chain blockade, recurrent laryngeal nerve blockade, spinal cord root injury
Supra/Infra-clavicular brachial plexus blockDistal humerus fractures
Elbow fractures
Forearm fractures
Upper arm skin soft tissue injuries		Ropivacaine 0.5% or lidocaine20-25 mLLower risk of phrenic nerve involvement than the interscalene approach but pneumothorax is a rare but serious complication
Axillary brachial plexus blockWrist/elbow/forearm bony injuryLidocaine +/- epi
Ropivacaine
Bupivacaine		15-20 mL (3-5 mL) per nerveChoice of LA will depend on desired duration of anesthesia
Axillary brachial plexus block + musculocutaneous nerve blockForearm skin soft tissue injuryLidocaine +/- epi
Ropivacaine
Bupivacaine		15-20 mL (3-5 mL) per nerveChoice of LA will depend on desired duration of anesthesia
Wrist blockHand bony or soft tissue injuries distal to wristLidocaine 1%3-5 ml per nerveDoes not provide analgesia for wrist fractures
Intercostal blockRib fractures
Chest tube placement		Ropivacaine
Lidocaine		3-5 mL per nerveHigh risk of cardiotoxicity, avoid bupivacaine
Serratus anterior plane (SAP) blockRib fractures
Chest tube placement
Thoracotomy
Chest wall or breast abscess		Ropivacaine
Lidocaine +/- epi		30 mLVolume is essential for any plane block. May dilute 1:1 with NS to achieve adequate volume
Erector Spinae plane blockPosterior rib fractures
Chest trauma		Ropivacaine30 mLVolume is essential for any plane block. May dilute 1:1 with NS to achieve adequate volume
TAP/ilioinguinal/iliohypogastric plane blockHernia reduction
ABD wall soft tissue injuries/abscesses		Lidocaine
Ropivacaine
Bupivacaine		30 mLVolume is essential for any plane block. May dilute 1:1 with NS to achieve adequate volume
Fascia iliaca compartment block (FIB)Hip fractures
Femoral shaft fractures		Bupivacaine 0.25%
Ropivacaine 0.25%		20-40 mLVolume is essential for effective FIB! May dilute 1:1 with NS to achieve adequate volume
Popliteal-sciatic (saphenous supplement) blockDistal tib/fib fractures
Lower leg SST injuries
Lower leg abscesses
Foot injuries		Lidocaine 1%
Ropivacaine 0.25%
Bupivacaine 0.25%		10-20 mL 
Posterior tibial blockSoft tissue injury to sole of the foot
Foreign body removal
Calcaneus fractures		Lidocaine 1%5 mL 
*Adapted from NYSORA.com

Conclusions

  • UGNBs have the potential to improve pain control, reduce opioid use, and improve patient outcomes.
  • The choice of local anesthetic should be based on the site of the block and the desired duration of analgesia.
  • There is currently inconclusive evidence for or against the benefits and risks of combining vasoconstrictors with local anesthetics to alter onset and duration of analgesia.

Self-Test Questions

Which of the following are potential complications of a fascia iliaca block?

  • a. Hematoma formation
  • b. Intravascular injection
  • c. Nerve injury
  • d. Local anesthetic systemic toxicity (LAST)
  • e. All of the above

References

  • American College of Emergency Physicians. Ultrasound-Guided Nerve Blocks.; 2021. doi:10.1111/j.1553
  • Liu SS. Evidence Basis for Ultrasound-Guided Block Characteristics Onset, Quality, and Duration. Reg Anesth Pain Med. 2016;41:205-220.

    • doi:10.1097/AAP.0000000000000141

  • Amini R, Kartchner JZ, Nagdev A, Adhikari S. Ultrasound-guided nerve blocks in emergency medicine practice. J Ultrasound Med.
  • 2016;35(4):731-736. doi:10.7863/ultra.15.05095
  • Lexicomp Online, Ohio: UpToDate, Inc.; 2013; May 12, 2021.
  • Beaudoin FL, Haran JP, Liebmann O. A comparison of ultrasound-guided three-in-one femoral nerve block versus parenteral opioids alone
  • for analgesia in emergency department patients with hip fractures: A randomized controlled trial. Acad Emerg Med. 2013;20(6):584-591.

    • doi:10.1111/acem.12154

  • Bhoi S, Sinha TP, Rodha M, Bhasin A, Ramchandani R, Galwankar S. Feasibility and safety of ultrasound-guided nerve block for
  • management of limb injuries by emergency care physicians. J Emergencies, Trauma Shock. 2012;5(1):28-32. doi:10.4103/0974-2700.93107
  • Mori T, Nomura O, Ihara T. Ultrasound-guided peripheral forearm nerve block for digit fractures in a pediatric emergency department ☆.
  • Am J Emerg Med. 2019;37:489-493. doi:10.1016/j.ajem.2018.11.033
  • Cisewski DH, Alerhand S. "SCALD-ED" BLOCK: SUPERFICIAL CUTANEOUS ANESTHESIA IN A LATERAL LEG DISTRIBUTION WITHIN THE EMERGENCY
  • DEPARTMENT-A CASE SERIES. J Emerg Med. 2019;56(3):282-287. doi:10.1016/j.jemermed.2018.12.005
  • Barton DJ, Marino RT, Pizon AF. Multimodal analgesia in crotalid snakebite envenomation: A novel use of femoral nerve block. Am J Emerg
  • Med. 2018;36:2340.e1-2340.e2. doi:10.1016/j.ajem.2018.09.020
  • Blaivas M, Adhikari S, Lander L. A prospective comparison of procedural sedation and ultrasound-guided interscalene nerve block for
  • shoulder reduction in the emergency department. Acad Emerg Med. 2011;18(9):922-927. doi:10.1111/j.1553-2712.2011.01140.x Answer Key
  • E
  • C
  • D
  • B
  • C
Tags:ultrasound nerve blocks bupivacaine lidocaine