Muise K L, Duchon M A, Brown R H
Department of Obstetrics and Gynecology, University MacDonald Womens Hospital, Cleveland, OH.
Am J Obstet Gynecol. 1992 Oct;167(4 Pt 1):1125-9. doi: 10.1016/s0002-9378(12)80053-6.
Our objective was to describe the effect of off-axis traction on the performance of modern vacuum extractors.
Eight vacuum extractors were examined in the laboratory with a force indicator and fetal cephalic model. Devices evaluated included the 6 cm Malmstrom, Mity-Vac, M-Type, O'Neil, Posterior, Silc, Tender-Touch, and silicone elastomer. Maximal tractive force (pop-off) was measured for each device at 10-degrees increments from the vertical.
Multivariate regression analysis described the best model as follows: Maximal tractive force = Constant + Angle + Vacuum (p < 0.05). The partial regression coefficients for angle were negative in all devices except the Posterior cup. At increasing angles of off-axis traction, maximal tractive force decreased in the following order: Silc, silicone elastomer, Tender-Touch, M-Type, Mity-Vac, O'Neill, Malmstrom, and Posterior.
Application of oblique traction resulted in a linear decline in maximal tractive force. An understanding of in vitro performance may allow tailoring of cup selection to the clinical situation.
我们的目的是描述轴外牵引对现代真空吸引器性能的影响。
在实验室中使用力指示器和胎儿头部模型对八台真空吸引器进行检测。评估的器械包括6厘米的马尔姆斯特伦吸引器、米蒂真空吸引器、M型吸引器、奥尼尔吸引器、后路吸引器、西尔科吸引器、温柔触感吸引器和硅橡胶弹性体吸引器。从垂直方向开始，以10度的增量测量每个器械的最大牵引力（弹出力）。
多元回归分析得出的最佳模型如下：最大牵引力=常数+角度+真空度（p<0.05）。除后路杯形吸引器外，所有器械角度的偏回归系数均为负。随着轴外牵引角度的增加，最大牵引力按以下顺序下降：西尔科吸引器、硅橡胶弹性体吸引器、温柔触感吸引器、M型吸引器、米蒂真空吸引器、奥尼尔吸引器、马尔姆斯特伦吸引器和后路吸引器。
斜向牵引的应用导致最大牵引力呈线性下降。了解体外性能可能有助于根据临床情况选择合适的杯形吸引器。
