by Bret P. Nelson, MD, RDMS, FACEP
Ultrasound-guided regional anesthesia (UGRA) is an emerging application of point-of-care sonography. Once solely the purview of anesthesiologists, other specialists are now realizing the benefits of these procedures and gaining competency in their performance.
Two recent review articles summarize key blocks nicely:
- De Buck F, Devroe S, Missant C, Van de Velde M. Regional anesthesia outside the operating room: indications and techniques. Curr Opin Anaesthesiol. 2012 Aug;25(4):501-7 (PMID: 22673788)
- Antonakakis JG, Ting PH, Sites B. Ultrasound-guided regional anesthesia for peripheral nerve blocks: an evidence-based outcome review.Anesthesiol Clin. 2011 Jun;29(2):179-91. (PMID: 21620337)
Ultrasound-Guided Regional Anesthesia Landmark approach
Traditionally, the only method for performing procedures was using anatomic landmarks. For example a femoral nerve block would be performed by first locating the femoral crease and then palpating the pulse of the femoral artery. The needle would be inserted lateral to the femoral artery.
Nerve Stimulator approach
Use of the nerve stimulator increased success rates and the ability to perform more difficult blocks. When using a nerve stimulator the needle is still attached to a syringe of anesthetic solution. However it is also attached to a nerve stimulator which creates a mild (typically less than 0.5 mA) current. Position of the needle tip is confirmed by muscle twitch. For example, quadriceps muscle twitch when performing a femoral nerve block.
In the past decade many providers have moved from nerve stimulation to ultrasound guidance, in part due to data studies such as this one:
- Abrahams MS, Aziz MF, Fu RF. et al. Ultrasound guidance compared with electrical neurostimulation for peripheral nerve block: a systematic review and meta-analysis of randomized controlled trials. Br J Anaesth 2009 Mar;102(3): 408-417 (PMID: 19174373)
Most recently ultrasound guidance has become the method of choice for many clinicians performing regional nerve blocks. It can be used alone or in combination with nerve stimulation. In the video below the femoral artery is seen pulsating to the screen right; to the screen left a growing anechoic space represents anesthetic being infiltrated around the femoral nerve. Note that in this video the operator is using a nerve stimulator in addition to ultrasound guidance.
There are a number of nerve blocks commonly employed in acute care and operative settings. Many are reviewed on NYSORA’s website. Here are a few to consider if you are new to the technique:
- Femoral nerve block: Helpful for femur, knee, thigh injuries
- Forearm block: helpful for hand injuries
- Interscalene brachial plexus block: helpful for shoulder, humerus, elbow injuries
For further information regarding nerve blocks please check out the resources listed in this post, as well as the anesthesiologists, emergency physicians, pain management and/or sports medicine physicians at your local institution. To learn more about Ultrasound-Guided Regional Anesthesia, check out the upcoming courses by Gulfcoast Ultrasound Institute.