Ultrasound-Guided Perineural Catheter Insertion

Abstract

A s ultrasound-guided regional anesthesia becomes more popular and practiced, a plethora of research involving this relatively new modality is being publishedVto the degree that Regional Anesthesia and Pain Medicine recently added an entire ultrasound-related section to every issue. However, most of these reports involve single-injection peripheral nerve blocks, to the exclusion of perineural catheter insertion. Unfortunately, data from many of these publications cannot be automatically inferred to perineural catheter placement for multiple reasons. First, although the angle between the long axis of the placement needle and nerve is relatively unimportant for single-injection blocks, it is critical for perineural catheter insertion because catheters tend to exit the needle and traverse past any nerve that is perpendicular to the needle itself. Second, a major advantage of ultrasound guidance for single-injection nerve blocks lies in the real-time repositioning of the needle tip to maximize local anesthetic spread, whereas perineural catheter bolus and/or infusion is analogous to a single-point injection. Third, unlike needles, flexible perineural catheters rarely remain within a 2-dimensional ultrasound view, making it difficult to observe catheter tip placement relative to the target nerve. Although it is impossible to include all ultrasound-guided techniques and respective equipment, the purpose of this editorial is to briefly review the major ultrasound-guided catheter insertion approaches along with their relative potential strengths and weaknesses.