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
Key Points
- UGNBs are ACEP-endorsed as a core emergency-medicine skill and a key component of a multimodal, opioid-sparing pain pathway.
- Ultrasound guidance shortens time to block onset and improves block quality compared with other techniques.
- Reported benefits include improved post-surgical function, decreased delirium, and shorter length of stay.
- Screen for contraindications before performing a block and remain vigilant for local anesthetic systemic toxicity (LAST).
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
MOA: Anesthetics 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.
Regional Anesthetic Pharmacology
| Parameter | Lidocaine | Lidocaine w/ epi | Bupivacaine | Ropivacaine | Mepivacaine |
|---|---|---|---|---|---|
| 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) |
| Onset | 4–7 min | 4–7 min | ~20 min | ~15 min | ~10 min |
| Duration of Analgesia | ~2 hours | ~3–4 hours | ~6–8 hours | ~6–8 hours | ~2–3 hours |
*Dose will vary with block location due to differences in vascularity, size of the nerve, and the duration of anesthesia required.
Administration
- 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
| Author, year | Design & Sample Size | Patient Population | Intervention & Comparison | Outcome |
|---|---|---|---|---|
| Beaudoin et al., 2013 | Randomized 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., 2012 | Prospective observational feasibility study (N=50) | Patients ≥5 yrs requiring analgesia for acute limb emergencies | Brachial 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., 2019 | Retrospective case series (N=6) | UG ulnar nerve block prior to phalangeal reduction in pediatric patients | 0.1–0.2 mL/kg lidocaine 1% | No patients required additional analgesia; All patients were discharged home after completion of reduction; No documented complications |
| Cisewski & Alerhand, 2019 | Case 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., 2018 | Case report (N=1) | 44 yr male with copperhead bite to left hallux | Fascia 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., 2011 | RCT (N=42) | Patients in the ED with shoulder dislocations | Procedural 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
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
1. 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
Show answer
Answer: E. All of the above
2. Which of the following local anesthetics would be preferred for an interscalene brachial plexus block?
- a.Bupivacaine 0.5%
- b.Ropivacaine 0.25%
- c.Lidocaine 1% – short duration of action
- d.Lidocaine 4%
Show answer
Answer: C. Lidocaine 1% – short duration of action
3. What is the maximum dose of bupivacaine 0.25% that can be used for a fascia iliaca block on a 200 kg patient?
- a.225 mg
- b.205 mg
- c.185 mg
- d.175 mg
Show answer
Answer: D. 175 mg
4. What is the recommended volume of local anesthetic for a fascia iliaca block?
- a.0–15 mL
- b.20–40 mL
- c.50–70 mL
- d.80–100 mL
Show answer
Answer: B. 20–40 mL
5. After completing an UGNB with bupivacaine 0.5%, how long should you wait before beginning your procedure?
- a.5 min
- b.10 min
- c.15 min
- d.45 min
Show answer
Answer: C. 15 min
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
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