Prospective randomized study of preprocedural ultrasound scan for spinal anesthesia 1 comparison between using 2nd prototype of PASS and skin marking technique to locate needle entry point

Abstract

Background: Pre-procedure ultrasound scans can indicate the midpoint of the puncture site of spinal injection. However, there are limitations of the technic. Objectives: To compare the success rate of spinal anesthesia by preprocedural ultrasound scan to compare 2 needle puncture technics between using Point-Assisted Spinal Sonography (PASS) and skin marking. Methods: Forty-eight patients undergoing elective spinal anesthesia were randomized to receive preprocedural ultrasound scan with transverse interspinous view to locate the needle puncture, using either the 2nd prototype of PASS (n=24) or skin marking (conventional) (n=24). The conventional technic was done by making the intersection point of the two lines across the short and long edges of the transducer, whereas the other used PASS to guide the needle trajectory. The primary outcome was the success rate of spinal tap at the first attempt. The number of total attempts and spinal tap duration to obtain the CSF were recorded as secondary outcomes. Results: The success rate of spinal tap at the first attempt was 9/24 (37.5%) patients in PASS and 11/24 (45.8%) in skin marking group (P=0.55). Spinal tap duration and the number of total attempts were not statistically different (P=0.55 and 0.49 respectively). Conclusion: The 2nd prototype of PASS produces comparable successful spinal block with using skin marking technic in terms of success rate at the first attempt and procedure time. Needling without marks or gel in PASS technic might take less risk of intrathecal contamination.