Microfabricated Implantable Flowmeter for CSF Shunts

描述（由申请人提供）：提出了一种可植入的无线流量计，用于测量脑室-腹膜（VP）分流的脑脊液（CSF）流量，目前用于治疗脑积水患者。脑脊液流量是分流功能的关键指标，目前尚无原位测量方法，导致临床缺乏直接评估分流功能或预测其失效的方法。使用MEMS微加工方法，所提出的流量计将以足够小的尺寸制造，以与植入的VP分流器集成。流量计的关键元件是电容结构，其特性随脑脊液流量的变化而变化。内部无源电路和外部检测电路之间的放射性耦合允许在不需要植入电池或经皮导线的情况下植入流量计。拟议的第一阶段项目将设计和制造一套MEMS流量传感器原型，然后对其进行检查和台架测试以确定关键参数。与此同时，无线询问传感器所需的电子电路将被设计、组装和测试。为了执行要求在现实条件下测试传感器的协议，将构建一个测试台，允许精确控制流量。将对流量计进行测试，以确认它能够满足一些评估标准：测量范围、精度和测量对方向和环境条件的不敏感性。此外，模拟工作分流的测试将评估生物相容性涂层在防止传感器阻塞形成方面的有效性。第一期工程完成后，我们将会证明建议装置的可行性。II期完成后，我们打算开发一种无线流量传感器，可作为仪器化VP分流器的一部分，用于治疗脑积水。公共卫生相关性：为了纠正脑室-腹膜（VP）分流术治疗脑积水患者相对常见的失败，美国每年大约有23,000例分流术修复。然而，儿童仍然死于分流失败，研究表明，早期发现将挽救这些儿童的很大一部分。可植入的无线脑脊液流量计将使临床医生能够在常规办公室就诊时监测分流功能（而不是等待脑积水症状的再次出现），允许检测即将发生的分流衰竭，避免在紧急情况下进行挽救生命的治疗，并降低与VP分流衰竭相关的死亡率。

DESCRIPTION (provided by applicant): An implantable wireless flow meter is proposed that would enable measurement of the flow of cerebrospinal fluid (CSF) through the ventriculoperitoneal (VP) shunt, currently used to treat hydrocephalus patients. CSF flow is a key indicator of shunt function, and there is currently no way to measure it in situ, resulting in the absence of clinical methods to directly assess shunt function or to predict its failure. Using MEMS microfabrication methods, the proposed flow meter will be manufactured at a size small enough to be integratable with implanted VP shunts. The key elements in the flow meter are capacitive structures that change properties with change in CSF flow. Radioactive coupling between the internal passive circuitry and an external detection circuit allows implantation of the flow meter without the need for implanted batteries or transcutaneous wires. The proposed Phase I project will design and fabricate a set of MEMS flow sensor prototypes, which will then be inspected and bench tested to confirm key parameters. In parallel, the electronic circuitry required to wirelessly interrogate the sensor will be designed, assembled and tested. In order to perform a protocol that calls for testing of the sensor under realistic conditions, a test stand will be constructed that allows precise control of flow. Tests will be undertaken with the flow meter to confirm that it can meet a number of evaluation criteria: measurement range, accuracy, and measurement insensitivity to orientation and ambient conditions. In addition, testing which simulates a working shunt will evaluate the effectiveness of biocompatible coatings in preventing formation of occlusions in the sensor. Upon completion of Phase I, we will have proved feasibility of the proposed device. Upon completion of Phase II we intend to have developed a wireless flow sensor that could be included as part of an instrumented VP shunt for the treatment of hydrocephalus. PUBLIC HEALTH RELEVANCE: Every year there are approximately 23,000 shunt revisions performed in the U.S., in order to correct the relatively common failure of ventriculoperitoneal (VP) shunts used to treat hydrocephalus patients. However, children are still dying from shunt failure, and studies indicate that earlier detection would save a large fraction of these children. An implantable, wireless CSF flow meter would enable the clinician to monitor shunt function during routine office visits (rather than waiting for the re-appearance of hydrocephalus symptoms), allowing detection of impending shunt failure, avoidance of lifesaving treatment on an emergency basis, and reduction of mortality associated with VP shunt failure.