Update on Ultrasound for Truncal Blocks: A Review of the Evidence.

We summarized the evidence for ultrasound (US) guidance for truncal blocks in 2010 by performing a systematic literature review and rating the strength of evidence for each block using a system developed by the United States Agency for Health Care Policy and Research. Since then, numerous studies of US guidance for truncal blocks have been published. In addition, 3 novel US-guided blocks have been described since our last review. To provide updated recommendations, we performed another systematic search of the literature to identify studies pertaining to US guidance for the following blocks: paravertebral, intercostal, transversus abdominis plane, rectus sheath, ilioinguinal/iliohypogastric, as well as the Pecs, quadratus lumborum, and transversalis fascia blocks. We rated the methodologic quality of each of the identified studies and then graded the strength of evidence supporting the use of US for each block based on the number and quality of available studies for that block. WHAT'S NEW: Since our last review, numerous studies have been published, especially for the paravertebral and transversus abdominis plane blocks, and 3 novel US-guided blocks (Pecs, quadratus lumborum, and transversalis fascia blocks) have been described. Although some of these studies support the use of US for performing these blocks, others do not. Additional studies have used US to improve our understanding of the anatomy pertinent to these blocks and evaluated the effect on patient outcomes and risk of complications.