Purpose

Total and partial proximal catheter occlusions are well-known complications of ventriculoperitoneal shunts (VPS). When this occurs, surgeons often attempt to perform a shunt tap. However, the degree of obstruction in a proximal catheter that ultimately leads to shunt malfunction is unknown.

Methods

We developed a benchtop model to simulate proximal catheter occlusion with two hydrostatic reservoirs connected by a VPS catheter system. The Centurion compass device was used to measure pressure across the valve digitally. Wires of varying diameters (equalling different occlusion percentages) were inserted into the catheter’s proximal end to stimulate obstruction. A mock shunt tap aspiration was then performed by incorporating a pressure transducer.

Results

As a general trend, pressure reading on the device decreases as occlusion increases. At higher levels of occlusion (> 45%), the blockage begins to significantly impede the flow through the catheter, and the pressure drops at a faster rate compared with lower occlusion percentages. The pressure reading converges quickly to 0 with increasing blockage after about 70%. The Centurion compass is able to detect large changes in pressure as evidenced by the major differences in pressure readings between no occlusion, 45%, and 84%. The shunt will not function at 84%. In order to determine the threshold for occlusion beyond which fluid cannot be withdrawn, we tested five levels of occlusion (0%, 33%, 63%, 84%, and 100%) at various aspiration pressures and determined that fluid can still be produced with 0–84% occlusion, but no fluid could be produced at 100% occlusion.

Conclusions

We developed a model of proximal shunt obstruction and found that cerebrospinal fluid (CSF) flow through a VPS is unaffected up to 33% occlusion, begins to become impaired at 45% occlusion, and is miniscule at 84% occlusion. Shunt aspiration was not possible at 84% occlusion. Pressure measured at the reservoir is accurate and correlates with intracranial pressure (ICP) up to approximately 60% proximal occlusion. With partial occlusion up to 70%, ventricular pressure will dictate shunt function.

中文翻译：

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导管近端阻塞的模拟和分流抽吸系统的设计

目的

完全和部分近端导管阻塞是心室腹膜分流（VPS）的众所周知的并发症。发生这种情况时，外科医生通常会尝试进行分流水龙头。但是，最终导致分流器故障的近端导管阻塞程度尚不清楚。

方法

我们开发了一个台式模型，以模拟通过VPS导管系统连接的两个静水容器形成的近端导管阻塞。Centurion罗盘设备用于以数字方式测量整个阀门的压力。将直径不同（相等的遮挡百分比不同）的金属丝插入导管的近端以刺激阻塞。然后通过并入压力传感器进行模拟分流抽头抽吸。

结果

通常，随着阻塞的增加，设备上的压力读数会降低。在较高的阻塞水平（> 45％）下，堵塞开始显着阻碍通过导管的流量，并且与较低的阻塞百分比相比，压力下降的速度更快。大约70％之后，压力读数迅速收敛到0，并且阻塞增加。Centurion指南针能够检测到压力的大变化，如无阻塞，45％和84％之间的压力读数的主要差异所证明。分流器将无法以84％的速度运行。为了确定无法抽出积液的闭塞阈值，我们在各种抽吸压力下测试了五种闭塞程度（0％，33％，63％，84％和100％），并确定仍然可以产生积液。遮挡0–84％，

结论

我们开发了近端分流阻塞的模型，发现流经VPS的脑脊液（CSF）在阻塞高达33％时不受影响，在阻塞45％时开始受损，在阻塞84％时微不足道。阻塞84％时无法进行分流抽吸。在储层处测得的压力是准确的，并且与颅内压（ICP）相关，最高达近端阻塞的60％。当部分阻塞达到70％时，心室压力将决定分流功能。