Mechanical needle guidance for ultrasound-guided parasagittal oblique in-plane paravertebral blocks: a cadaveric study

Background: Paravertebral blocks provide analgesia for a range of thoracoabdominal surgeries. However, visualizing the needle tip during the procedure can be challenging, especially for clinicians with limited experience, because the target is deep. We therefore tested the primary hypothesis that needle guidance by the Infiniti Plus system improves ultrasound visualization of the needle tip during thoracic paravertebral blocks performed by novice residents. Methods: Nineteen clinical anesthesia residents each performed 20 bilateral ultrasound-guided thoracic paravertebral blocks (T2–T11) on 17 unembalmed cadavers, with and without the use of a fixed-angle mechanical needle guide in a randomized crossover design. The primary outcome, percent perfect needle visibility, was compared between guided and unguided methods using a paired t-test. Secondary outcomes, including time to needle visualization, number of needle insertion attempts, and subjective ease-of-use ratings, were analyzed using paired t-tests and Wilcoxon signed-rank tests, respectively. Inter-rater reliability for overall perception ratings was assessed using the Intraclass Correlation Coefficient (ICC). Results: There were no significant differences in needle-target visualization (62% ± 17% with guidance vs. 64% ± 18% without, p = 0.15), time to target (HR = 1.00 [95% CI 0.86–1.16], p = 0.99), procedural difficulty scores, or number of insertion attempts between guided and unguided blocks. Conclusion: The Infiniti Plus mechanical needle guide did not demonstrate improved ultrasound needle tip visualization during thoracic paravertebral blocks performed by novice clinicians in cadavers.