Importance of the needle bevel during spinal and epidural anesthesia.

ABSTRACT

BACKGROUND AND OBJECTIVES: The needle bevel has an important effect on the path that the needle takes as it traverses tissue. Many anesthesiologists, especially trainees, are unaware of the magnitude of this effect. There is a need for a model, constructed from readily available materials, that can be used to demonstrate the bevel effect and to assess various strategies for accurately advancing the needle. METHODS: Styrofoam blocks were prepared. The following needles were studied 25-gauge Quincke, 22-gauge Quincke, 18-gauge Quincke, 24-gauge Sprotte, 25-gauge Whitacre, 22-gauge Tuohy, and 17-gauge Tuohy. The effect of bevel orientation on deflection from midline was measured. Representative results were photographed. RESULTS: The bevel has a significant effect on the path of Quincke and Tuohy needles. The deflection is more pronounced for thinner needles. Pencil-point needles show much less deflection than Quincke needles. CONCLUSIONS: Styrofoam blocks provide a model for teaching the basics of spinal and epidural anesthesia. By utilizing styrofoam the trainee can master needle control and gauge the effect of bevel orientation.