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October 16, 2018
10/16/2018 1:15:00 PM - 10/16/2018 2:45:00 PM
Room North, Room 22
Loss of Resistance Assessment Techniques Differ in Overshoot into a Simulated Epidural Space
Michael A. Cometa, M.D., Terrie Vasilopoulos, Ph.D., Anthony DeStephens, M.Eng., David Lizdas, B.S., Nikolaus Gravenstein, M.D., Samsun Lampotang, Ph.D., Andre Bigos, Student, Brandon M. Lopez, M.D.
University of Florida College of Medicine, Gainesville, Florida, United States
Disclosures: M.A. Cometa: None. T. Vasilopoulos: None. A. DeStephens: None. D. Lizdas: None. N. Gravenstein: None. S. Lampotang: None. A. Bigos: None. B.M. Lopez: None.
Introduction: Postdural puncture headache is a complication of accidental dural puncture (ADP) that occurs in 1.5% of routine epidural placements.1 Epidural simulators have been used to teach anesthesiology providers the loss of resistance (LOR) technique to identify the epidural space. Knowing the likelihood and magnitude of overshoot past LOR of different LOR assessment techniques may guide informed selection of LOR assessment technique, which in turn may help reduce ADP. Methods: After IRB approval and informed consent, we studied three LOR techniques on a custom-built mixed reality simulator2 with 45 providers: Incremental needle advancement, with Intermittent LOR assessment (II); Continuous needle advancement, with high-frequency Intermittent LOR assessment (CI); and Continuous needle advancement, with Continuous LOR assessment (CC). Each provider identified LOR using each approach 5 times with the LOR set at random depths in the simulator software. We used a linear mixed model for repeated measures to assess mean differences in overshoot beyond the LOR depth between techniques. We modeled LOR technique as a repeated measure to account for within-participant correlations. Secondary analyses included operator experience level (AA or CRNA, resident, fellow, or attending) as a fixed effect and as part of an interaction with technique (level × technique). Results: There were significant mean differences in maximum overshoot past a virtual LOR plane due to technique (F(2,43)=73.55, p<0.001; Figure). Specifically, maximum overshoot was greater with II (mean=3.8 mm, 95%CI: 3.4-4.3) vs. either CC (mean=1.9 mm, 95%CI: 1.5-1.8; p<0.001) or CI (mean=1.4 mm, 95%CI: 0.9-2.3; p<0.001). CC and CI were not statistically different (p=0.196). Experience level did not have a significant relationship with maximum overshoot (p=0.706) or a significant interaction with technique (p=0.194). Conclusion: The II LOR assessment technique demonstrated the greatest needle tip overshoot into the simulated epidural space after LOR could be felt. This was consistent across all experience levels. Our study demonstrates that the II LOR assessment technique results in the deepest needle advancement beyond actual LOR. If our simulator data are representative of what would occur in actual patients, our findings suggest ADP would be more likely with the II technique than with the CI or CC LOR assessment techniques. Our simulator-based data requires verification in a clinical study with actual patients.References: 1. Can J Anaesth 2003;50:460-9 2. Anesth Analg 2017 Nov 30. doi: 10.1213/ANE.0000000000002572. [Epub ahead of print]
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