A randomized controlled trial comparing static ultrasound guided lumbar puncture to the dynamic paramedian approach

The dynamic paramedian (DP) approach to lumbar puncture (LP) is a novel technique that allows for active ultrasound (US) guidance. We sought to investigate the efficacy of this approach as compared to traditional static US guidance using a cadaver model.

This was a prospective study between November 2024 and May 2025 at a single institution. Four ultrasound-trained emergency physicians performed simulated LPs on soft-embalmed cadavers using both the static midline (SMLP) and dynamic paramedian (DPLP) ultrasound approaches. For each spinal level, the order in which the techniques were performed was randomized. Outcomes evaluated included overall success, time, number of bony contacts, and number of needle redirections.

A total of 36 SMLP and 36 DPLP attempts were performed on four separate cadavers. Overall success was 72 % (95 %CI 56 %-84 %) for SMLP and 81 % (95 %CI 65 %-90 %) for DPLP, p = 0.6. Median time to completion for SMLP was 96 s (IQR 57.5-300) and 72 s (IQR 35.5-200.5) for DPLP, p = 0.07. Median bony contacts and needle re-directions were both lower with the DPLP approach compared to the standard approach (2 vs. 7, p = 0.0004; and 4 vs. 8.5, p = 0.011, respectively). The subcohort analysis of ultrasound-fellowship trained emergency physicians had a DPLP success rate of 96 % (95 %CI 82 %-99 %).

The DPLP approach to LP is a promising technique for the emergency physician. In a cadaveric model, it was associated with fewer bony contacts and needle redirections as compared to SMLP. Overall procedural success was higher with the DPLP approach, though this did not reach statistical significance.