Eg. Lipov et al., DOES THE DESIGN OF THE SPROTTE SPINAL NEEDLE REDUCE THE FORCE NEEDED TO DEFORM THE TIP, Journal of clinical anesthesia, 6(5), 1994, pp. 411-413
Study Objective: To determine whether the window design of pencil-poin
t spinal needles leads to deformation under lateral or axial loading c
onditions. Design: Independent-measure, multigroup study of the force
required to deform needles. Setting: Independent testing laboratory. M
easurements and Main Results: The force necessary to bend 22- and 24-g
auge Sprotte, 22- and 25-gauge Whitacre, and 22- and 25-gauge Quincke
needles was measured using an Instron gauge (Instron Corp., Canton, MA
) after microscopic verification of needle uniformity. Effects of late
ral and axial forces were evaluated in separate experiments. The force
needed to bend the Sprotte needles was less than that needed for the
Whitacre and Quincke needles of similar size when lateral or axial pre
ssure was applied. Microscopic inspection of the needles showed a mark
ed variability in the window area placement in a single lot of Sprotte
needles. Examination of the needle tips demonstrated that the Sprotte
needles were most likely to bend at the needle window, while the Quin
cke and Whitacre needles deformed at the point of clamping. Conclusion
s: The Sprotte needles have an inherent design weakness to lateral and
axial pressure, which may result in a greater number of needle tip de
formations upon needle insertion. The nature of this deformation may r
esult in difficulty in needle withdrawal and possibly fracture of the
needle tip.