AN ANALYSIS OF THE BUCKLING BEHAVIOR OF SPINAL ANESTHESIA NEEDLES

The use of large gauge (G) spinal anesthesia needles can increase complications due to buckling. The purpose of this study was to, first, create a model to repeatably simulate and quantify the behavior of spinal needles in buckling and, second, quantify the buckling behavior of spinal anesthesia needles with respect to the relative contribution of needle gauge, brand, tissue depth (i.e. patient size) and the use of a stylet. A repeatable spinal anesthesia procedure and buckling complication was simulated using a custom test fixture designed to match the boundary conditions of needle insertion as performed by an anesthesiologist and a uniaxial servohydraulic material testing machine (MTS, Eden Prairie MN). Buckling tests were performed with 22G, 24G, 25G and 27G BD Whitacre, Havel Pajunk, Gertie Marx and B.Braun Pencan needles in a ballistics gelatin tissue surrogate. In analyzing axial force changes, critical buckling load results were 27.65±0.918N. Due to the large force magnitude that can be withstood by spinal needles in compression, it can be concluded that the problem of needle buckling is not a consequence of needle fragility. The differential between the resultant insertion force and the critical buckling force is more important to the detection of needle buckling than the critical buckling force alone. In clinic, a very small difference in these two forces could feel like expected resistance increase as the needle is further inserted into the multiple tissue layers. Comparison of the differential between the resultant insertion force and the critical buckling force, termed ∆FIC, should be considered when choosing a needle to best detect and prevent a buckling complication. Needle gauge was the most significant factor affecting ∆FIC results, followed by tissue depth, needle brand and use of a stylet. The results of this study can be used to determine which needle type is best for each patient. We hope that the information obtained from this study will help us obtain our long-term goal of improving spinal anesthesia procedural safety.

Grantor dc:publisher

Wake Forest University

Year dc:date.issued

2018

Author dc:creator

• Hulburt, Tessa

Language dc:language.iso

en

Handle dc:identifier.uri

http://hdl.handle.net/10339/93045

OAI identifier oai:identifier

oai:wakespace.lib.wfu.edu:10339/93045