Basic Nerve Block Principles

Learning Objectives:

  1. Perform procedural guidance in both transverse and longitudinal approaches (when appropriate) for regional anesthesia

  2. Identify relevant US anatomy for each particular procedure/block

  3. Recognize relevant findings & pitfalls

  4. Integrate US for regional anesthesia into individual patient and departmental management

Indications:

  • Regional anesthesia for multimodal analgesia

Safety First

  • Include consent and baseline neurovascular examination.

  • Ensure appropriate sterile technique.

  • Calculate cumulative local anesthetic dose, especially when combining blocks.

  • Always aspirate for blood prior to injecting anesthetic and inject incrementally. If injection fails to produce a resulting bolus on the ultrasound image, stop injecting and reposition.

  • Stop for severe pain, high resistance, or nerve swelling as this can indicate intraneural injection.

  • Avoid intravascular injection. If intravascular injection of local anesthetic occurs, then the physician must recognize the potentially life-threatening complication of local anesthetic systemic toxicity (LAST).

  • LAST (Local Anesthetic Systemic Toxicity): when a large volume of local anesthetic reaches the systemic circulation and causes toxicity -> can lead to central nervous system and/or cardiovascular collapse.

    • When performing large volume nerve blocks, be sure to have your patient on the cardiac monitor and call pharmacy to ensure intralipid is available.

    • If LAST leads to cardiovascular collapse, follow ACLS protocols.

supplies:

  • High-frequency linear ultrasound transducer

  • Chlorhexidine skin prep

  • Blunt-tip block needle preferred if available

  • Local anesthetic

  • Sterile gel and transducer cover (optional)

  • Sterile gloves (optional)

Views:

  • Needle-in-plane clip of your needle in the correct anatomic location

  • Clip of your saline/anesthetic hydrodissecting the correct fascial plane

How to:

ACEP Sonoguide:Ultrasound Guided Nerve Blocks

Core Ultrasound: Nerve Blocks

Highland Ultrasound

Tips/Tricks/Pitfalls:

  • Recommend in-plane technique for nerve blocks as you want to visualize surrounding structures and the entire needle (including the tip) during the procedure

  • It can sometimes be difficult to differentiate between nerve and tendon for peripheral blocks. Track your tendon proximally until it turns into muscle to confirm your structures

Full Text Literature:

  1. Lee et al. Assessing PA students ability to identify regional landmarks of the fascia iliaca after a brief training session

  2. Situ-La Casse et al. Performance of Ultrasound-guided Peripheral Nerve Blocks by Medical Students After One-day Training Session

  3. Ketelaars et al. Emergency physician-performed ultrasound-guided nerve blocks in proximal femoral fractures provide safe and effective pain relief: a prospective observational study in The Netherlands

Additional Resources:

Malin and Dawson iBook Volume 2

  • Chapter 5: Femoral Nerve Block

  • Chapter 6: Peripheral Nerve Blocks

The POCUS Atlas- Nerve Block Atlas

Blockheads Regional Anesthesia

Regional Anesthesiology

Baby Blocks - an excellent pediatrics focused resources, but the principles apply broadly

AEUS Lecture Introduction to Ultrasound Guided Nerve Blocks Rock the Block by Michael Heffler

NYSORA Topics

NYSORA Techniques

Author: Susan Mari, MD (Class of 2026) | Reviewed by: Christine Jung, MD-FPD