P003: EPIDURAL LOSS OF RESISTANCE TECHNIQUES - WHEN MILLIMETERS MATTER: A SIMULATOR STUDY.
M. Anthony Cometa, MD, Terrie Vasilopoulos, PhD, Anthony Destephens, Andre Bigos, David Lizdas, Nikolaus Gravenstein, MD, Samsun Lampotang, PhD, Brandon Lopez, MD; University of Florida
Introduction: Postdural puncture headache (PDPH) is a complication of accidental dural puncture (ADP) that occurs in 1.5% of routine epidural placements . Simulation has demonstrated efficacy in medical education. Epidural simulators have been used to teach anesthesiology providers the loss of resistance technique employed to identify the epidural space . We explored if there is a potentially best technique to decrease the likelihood of traversing the epidural space and associated ADP.
Methods: Three LOR techniques were studied: Incremental needle advancement, with Intermittent loss of resistance assessment (II); Continuous needle advancement, with high frequency Intermittent loss of resistance assessment (CI); Continuous needle advancement, with Continuous loss of resistance assessment (CC). Each subject was asked to identify LOR using each approach 5 times with the simulator LOR at random depths. A linear mixed model for repeated measures was used to assess mean differences in overshoot between techniques. Technique was modeled as a repeated measure to account for within-participant correlations. Secondary analyses also included operator experience level (AA or CRNA, Resident or Fellow, and Attending) as a fixed effect and as part of an interaction with technique (level x technique).
Results: The primary outcome measure was needle overshoot (measured in millimeters) after LOR was obtained. There were significant mean differences in overshoot due to technique (F(2,39) [BL1] = 56.29, p < 0.001). Specifically, overshoot was greater in II (mean = 3.8mm, 95%CI: 3.4 – 4.2) vs. either CC (mean = 1.8mm, 95%CI: 1.4 – 2.2; p <0.001) or CI (mean = 1.4mm, 95%CI: 1.0 – 1.8; p < 0.001). CC and CI were not statistically different (p = 0.179). Training level did not have a significant relationship with overshoot (p = 0.317) nor a significant interaction with technique (p = 0.447).
Conclusion: The II LOR assessment technique demonstrated the greatest needle overshoot into the simulated epidural space after LOR was obtained. This was consistent across all experience levels; as such, this simulator study demonstrates that the II LOR assessment technique results in the deepest needle advancement technique and potentially makes ADP more likely than with either the CI or CC LOR identification techniques.