An introduction to femoral nerve and associated lumbar plexus nerve blocks under ultrasonic guidance

Abstract

The femoral nerve block is a useful anesthetic adjunct for many surgical procedures of the lower extremity. Although this procedure can be performed based on surface anatomy and nerve stimulation, clinicians are often challenged in patients with poor landmarks, obesity, and anatomic variations. Recent reports demonstrate the striking ability of ultrasound to image neural structures and associated fascial planes. Ultrasound has emerged as an important tool in regional anesthesia and its applications are still evolving. Ultrasound guidance has been shown to improve onset time and reduce the volume of local anesthetic solutions required to implement block placement and the incidence of inadvertent vascular punctures during the placement of femoral nerve blocks. In this article, we describe current approaches for blockade of the femoral nerve and associated elements of the lumbar plexus (lateral femoral cutaneous nerve of the thigh and saphenous nerve) with ultrasound guidance. We also describe the use of ultrasound for related procedures including lumbar plexus block per se and continuous femoral nerve block techniques. By development of ultrasound-guided techniques, we hope to improve efficacy and reduce complications of a wide variety of peripheral nerve blocks.