Shlansky-Goldberg R, Wing C M, LeVeen R F, Cope C
Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia 19104.
J Vasc Interv Radiol. 1993 Jul-Aug;4(4):505-11. doi: 10.1016/s1051-0443(93)71906-5.
The authors evaluated the variable deployment of the Bird's Nest filter, including frequency and extent of prolapse in clinical use, and analyzed the effects of this variability on clot-trapping efficiency with an in vitro model.
In the clinical placement of 20 filters, the average length of cephalic filter wires from the center of the filter was measured from radiographs obtained immediately after placement. To analyze the effects of prolapse, a variable-rate pump was used to mimic the effects of respiration on IVC flow. Four clot sizes (5 x 20, 5 x 40, 10 x 20, and 10 x 40 mm) were evaluated with four filter configurations with wires stretched to different lengths in a cephalic direction from the center of the filter: 2 cm (normal-tight), 5 cm (normal-loose), 8 cm (moderate prolapse), and to a maximum of 12 cm (maximum prolapse). Ten passes for each clot size were performed with each filter configuration in both the horizontal and vertical positions. The smallest clots were also tested with a slower constant-rate pump.
In clinical use, the average length of the filter wire was 5.4 cm (range, 1.2-9.0 cm). With the variable flow pump, the in vitro degree of prolapse did not significantly decrease the trapping efficiency for any but the smallest (5 x 20-mm) clots, for the maximum prolapse configuration in the horizontal position (P = .01). In addition, for these clot sizes, the filter was more efficient with the slower constant rate compared with the faster variable rate; this difference was only statistically significant in the horizontal position for the maximum prolapse configuration (P = .007).
The results suggest that in clinical practice, a prolapsed Bird's Nest Filter remains effective for all but small clots.
作者评估了鸟巢式滤器的可变展开情况，包括临床应用中脱垂的频率和程度，并通过体外模型分析了这种变异性对血栓捕获效率的影响。
在20个滤器的临床放置过程中，从放置后立即获得的X线片上测量滤器头部滤线距滤器中心的平均长度。为分析脱垂的影响，使用变速泵模拟呼吸对下腔静脉血流的影响。评估了四种血栓大小（5×20、5×40、10×20和10×40毫米），以及四种滤器配置，滤线从滤器中心向头部方向拉伸至不同长度：2厘米（正常紧密）、5厘米（正常宽松）、8厘米（中度脱垂），最大至12厘米（最大脱垂）。每种滤器配置在水平和垂直位置对每种血栓大小进行10次通过测试。最小的血栓也用较慢的恒速泵进行测试。
在临床应用中，滤线的平均长度为5.4厘米（范围为1.2 - 9.0厘米）。使用变速泵时，除了最小的（5×20毫米）血栓外，体外脱垂程度并未显著降低捕获效率，水平位置最大脱垂配置除外（P = 0.01）。此外，对于这些血栓大小，与较快的变速相比，较慢的恒速时滤器效率更高；这种差异仅在水平位置最大脱垂配置时具有统计学意义（P = 0.007）。
结果表明，在临床实践中，除小血栓外，脱垂的鸟巢式滤器对其他血栓仍有效。
