Visibility of ultrasound-guided echogenic needle and its potential in clinical delivery of regional anesthesia.

OBJECTIVE Ultrasound-guided regional anesthesia is recommended for nerve block due to its safety and reliability. Needle visualization is important when inserting needles into tissues in close proximity to target nerves. For safety reasons, the tip of the standard-type needle for application of nerve block is thinner than that of an interventional needle for insertion into intra-abdominal organs, and this makes it harder to determine its precise position. The purpose of this study was to evaluate the performance of an insulated echogenic needle under ultrasound guidance in phantoms and in the routine anesthetic management of patients undergoing elective surgery. METHODS Needles with a 21-G diameter were inserted into Blue PhantomTM (Advanced Medical Technologies, LLC, WA) and chicken breast phantoms at angles of 15, 30, 45, 60, and 75 degrees relative to the surface. The needle was scanned by ultrasound using a TiTANTM (SonoSite, WA, USA). Visualization was compared between an insulated needle with corner cube reflectors (CCR-type: Hakko, Japan) and an insulated standard needle (S-type: Hakko, Japan). Both types of needle were also used to deliver regional anesthesia in patients with an ASA classification of PS1-2 undergoing elective surgery. RESULTS The tip of CCR appeared as 3 bright points under ultrasound, and was more hyperechoic than S. The CCR-type needle was clearly visible under ultrasound at insertion angles of 15, 30, and 45 degrees, and was consistently more hyperechoic than S. However, at steeper angles of > 60 degrees, visibility was poorer. In delivering clinical regional nerve block, CCR was usually more hyperechoic than S, allowing the nerve block points targeted to be accessed with greater ease. CONCLUSIONS The better visibility of the tip of CCR indicates that it is superior to S in the clinical delivery of peripheral nerve block.