Performing the Block
Prior to performing an anesthetic block at the ulnar, median, or radial nerve at the wrist, the clinician should first place the patient in a sitting or supine position with the appropriate elbow extended. When performing the block at the radial nerve above the elbow, the hand is typically placed in a resting position on the patient’s abdomen. When localizing the nerve, the angle of the transducer can vary the appearance of the nerve dramatically. To ensure the best possible view, the clinician should slowly “rock” the probe back and forth 10° to 20° in plane with the long axis of the arm, making sure the probe is placed as perpendicular as possible to the nerve. Once the nerve is identified, the clinician can follow it up and down the forearm with the probe to identify the best site to perform the block. In the optimal location, there should be a clear path that is as superficial as possible and avoids any vascular structures. We prefer using an in-plane technique to perform the nerve block to visualize the entire needle as it approaches the nerve. Once the site has been determined, the clinician should slowly inject 4 to 5 cc of anesthetic around the nerve, with the objective to partially surround the nerve. There is no need to completely surround the nerve, as doing so is not necessary to achieve a successful block. The clinician should stop immediately if the patient reports pain or if there is increased resistance, because this could indicate an intraneural injection.
Summary
Ultrasound-guided peripheral nerve blocks are an excellent option for providing regional anesthesia to lacerations and wounds that are too large for a local anesthetic. This technique can provide better analgesic relief, enhancing patient care.