Evidence Basis for Ultrasound Guidance for Lower-Extremity Peripheral Nerve Block: Update 2016.

This article reviews and summarizes randomized controlled studies that have investigated ultrasound guidance (USG) for lower-extremity peripheral nerve blocks in comparison with other peripheral nerve localization techniques and those that compared different ultrasound-guided techniques investigating optimal perineural local anesthetic distribution patterns.Thirty-four studies met the inclusion criteria (minimum Jadad score 3), and 10 additional studies directly compared USG with peripheral nerve stimulation, and 5 additional studies directly compared USG with landmark-based field blocks. Fourteen studies compared different local anesthetic distribution parameters.Analysis of the literature supports the use of USG for decreased block performance time, decreased block onset time, increased rate of complete sensory block, and increased analgesic efficacy. Ultrasound was never inferior to peripheral nerve stimulation. The research focus has evolved during the last 5 years into investigating optimal ultrasound-guided techniques.