Ultrasound guided regional anesthesia was first introduced in 1994, and it has since become a powerful tool for achieving adequate long-term pain control while avoiding the adverse effects associated with opiates.1 Although regional nerve blocks have become indispensable in the operating room, they have yet to become a fixture in the emergency department.
Ultrasound guided nerve blocks offer several advantages, which include direct visualization of neurovascular structures, real-time tactile feedback during block administration, and decreased risk of complications. Despite these benefits, ultrasound guided regional anesthesia is not yet mainstream in EDs across the country. Understanding these roadblocks will perhaps make this method of pain management more widespread, accessible, and available to patients who would benefit most.
A key barrier to ultrasound guided regional anesthesia is the educational gap that exists among emergency physicians.2 Nerve blocks are used most often in the setting of laceration repair or fracture management. Regional anesthesia in the distal extremities, such as the forearm nerve block or femoral nerve block, are relatively more common than proximal nerve blocks. The reason for the lag behind distal nerve blocks is that proximal blocks often involve more complex anatomy, such as the brachial plexus.3 The dexterity and advanced technical skill required to navigate around this neurovascular bundle instills hesitation in many physicians.
However, ultrasound guidance provides more accurate guidance than nerve stimulator-guided blocks. Overcoming this educational gap requires experience, preferably during the formative years of residency training. Institutions that have dedicated ultrasound fellowship trained faculty tend to graduate physician well versed in ultrasound guided regional anesthesia.
Furthermore, the fast-paced environment of the emergency department makes any procedure a hindrance to efficient workflow. The extra time it takes to perform an ultrasound guided nerve block is often enough to deter some individuals from implementing it. Opting to click orders for narcotics is easier and faster than doing a regional block, especially when compelled to acquiesce to the demanding nature of the ED. This time constraint applies especially to trauma EDs, where regional blocks are most often indicated.
With adequate experience, however, ultrasound guided regional anesthesia does not have to be a time-consuming procedure. Randomized control trials have confirmed that ultrasound guidance technology reduces both the time necessary to perform the block and the time to complete anesthesia. The time it takes can be as low as 9 minutes to complete anesthesia.4 This modest time investment rewards both the physician and patient with better pain control and satisfaction on both ends.
Lastly, the risks inherent to the anesthesia technique itself are a reason some may balk with the procedure. There is the risk of vascular puncture, hemidiaphragmatic paresis, pneumothorax, local anesthetic systemic toxicity, and permanent peripheral nerve injury.5 These complications are serious, but they are minimized by ultrasound guidance and safe technique. Vascular puncture can be easily avoided by carefully injecting around the vessel along the nerve sheath. Hemidiaphragmatic paresis is usually secondary to involvement of the phrenic nerve, typically with interscalene or supraclavicular brachial plexus blocks.6 Pneumothorax is also a valid concern with the supraclavicular block. These complications can manifest as significant dyspnea. Ultrasound can help guide the needle tip to avoid the pleura and prevent a pneumothorax.
The risks associated with local anesthetic systemic toxicity include the central nervous system (CNS) and the heart. The CNS is more sensitive to the effects than the cardiac system and will thus manifest symptoms first.7 Symptoms include tinnitus, blurred vision, dizziness, tongue paresthesias, circumoral paresthesias, and seizures.8 Cardiovascular toxicity generally begins after signs of CNS toxicity, affecting intracardial conduction and inhibition of myocardial energy supply and ion channels. This may lead to extreme bradycardia, ventricular arrhythmia, or refractory cardiac arrest.9 Permanent peripheral nerve injury is very rare. Caution must be exercised in patients taking digoxin, calcium channel antagonists, and/or beta-blockers.10 Taken together, these complications make ultrasound guided regional anesthesia a valuable asset that remains controversial. It will take a collective effort to overcome these barriers before this practice becomes widely adopted in EDs across the nation.
References
- Marhofer P, Greher M, Kapral S. Ultrasound guidance in regional anesthesia. Br J Anaesth. 2005;94(1):7-17.
- Wilson CL, Chung K, Fong T. Challenges and Variations in Emergency Medicine Residency Training of Ultrasound-guided Regional Anesthesia Techniques. AEM Education and Training. 2017;1(2):158-164.
- Kapral S, Krafft P, Eibenberger K, et al. Ultrasound-guided supraclavicular approach for regional anesthesia of the brachial plexus. Anesth Analg. 1994;78(3):507-513.
- Marhofer P, Sitzwohl C, Greher M, et al. Ultrasound guidance for infraclavicular brachial plexus anaesthesia in children. Anaesthesia. 2004;59(7):642-646.
- Richard A, Jeffrey K, Arun N, Srikar A. Ultrasound-Guided Nerve Blocks in Emergency Medicine Practice. J Ultrasound Med. 2016;35(4):731-736.
- El-Boghdadly K, Chin KJ, Chan VWS. Phrenic Nerve Palsy and Regional Anesthesia for Shoulder Surgery: Anatomical, Physiologic, and Clinical Considerations. Anesthesiology. 2017;127:173-191.
- Agarwal A, Kishore K. Complications and Controversies of Regional Anaesthesia: A Review. Indian J Anaesth. 2009;53(5):543-553.
- Di Gregorio G, Neal JM, Rosenquist RW, Weinberg GL. Clinical presentation of local anesthetic systemic toxicity: a review of published cases, 1979 to 2009. Reg Anesth Pain Med. 2010;35(2)181-7.
- Zink W, Graf BM. Toxicology of local anesthetics. Clinical, therapeutic and pathological mechanisms. Anaesthesist. 2003;52:1102-23.
- Naquib M, Maqboul MM, Samarkandi AH, Attia M. Adverse effects and drug interactions associated with local and regional anaesthesia. Drug Saf. 1998;18:221-50.