Verbesserung der Kanülensichtbarkeit in der ultraschallgesteuerten Regionalanästhesie - Untersuchungen zur Anwendung von Spatial Compound Imaging unter Berücksichtigung von echogenem Kanülendesign

Introduction: Ultrasound-guided regional anesthesia is used to perform surgery without the need for general anesthesia, or to deliver postoperative analgesic therapy. For being safe and reliable, direct and complete visualization of the introduced needle is a pivotal aspect. Due to the sonographic properties of conventional needles, their conspicuity decreases with increasing angle of incidence, which impedes the method. To adress this problem, dedicated echogenic needles have been designed. Such a needle, in combination with the ultrasound imaging mode “Spatial Compound Imaging” (SCI) has been investigated with respect to visualization and artifacts. Imaging of tissue and speckle artifacts when using SCI were additionally investigated aspects. Material and Methods: Conventional and echogenic needles have been inserted into formalin-embalmed cadavers at different angles of incidence, with videos of the ultrasound being stored. The videos were captured using SCI and conventional scanning. A blinded investigator rated the 200 videos on a 4-point scale in regard to visibility of needle shaft, needle tip, artifact formation by needle, quality of tissue imaging and speckle artifacts. Step-wise linear regression was used to calculate the influence of the evaluation criteria on visibility. Results: Use of the echogenic needle lead to a higher visibility of needle shaft and tip, especially at high angles of incidence. It also caused fewer artifacts. SCI too lead to better visualization of tip and shaft, as well as better tissue visualisation, less needle-caused artifacts and speckle artifacts. Conclusion: Echogenic needles improve visibility, especially at high angles of incidence. SCI improves visibility of conventional as well as echogenic needles and delivers a higher quality of tissue imaging. Combining both instruments can render the procedure more applicable, without causing additional effort. Influence on clinical use and training should be investigated in further studies.