A system to monitor the inlet pressure of rotary blood pumps

描述(申请人提供)：轴流旋转式血泵已成功应用于临床，以提供更长时间的机械循环支持，但这些设备不能提供负荷响应机制来调整泵性能以匹配静脉回流和生理需求的变化。这些设备中的大多数都以可调的固定速度运行，它们有可能产生过高的吸气压力，可能会对患者造成严重后果。为了提高旋转式血泵的安全性和有效性，提出了一种新型的旋转式血泵入口压力监测装置。传统的应变计传感器容易漂移，并且存在稳定性问题，不适合长期植入。该装置在椭圆形截面管道中采用了一个相对较大的位移膜片，其漂移由工作在射频下的平面变压器系统来检测。与移动的隔膜没有直接的物理接触。与根据电机电流等参数推断泵流入时血流动力学状况的控制算法不同，所建议的设备将使控制系统能够动态调整泵速度，以避免吸入压力过大并优化泵的血流。从本质上讲，这将使这些装置的运作类似于斯塔林定律装置，即流入时可用血液决定泵的输出。在第一阶段中，我们将设计新型的入口压力传感器，并对其静态和动态性能进行评估，以评估其在旋转血泵控制中的适用性。可行性的证明将包括显示该设备准确地测量入口管道压力，并且其响应时间将允许在逐拍或短期平均的基础上进行自动速度控制。与公众健康相关建议的装置是一种机电部件，旨在测量血液旋转泵进口管道中的压力，以防止吸入压力过大。该装置的输出将参考胸腔内压力。它的工作原理是监测椭圆形横截面弹性体导管的挠度，以响应其内部压力的变化。这种偏转是使用平面变压器系统测量的，该系统工作在对人体组织透明的射频上。不需要与导管的移动壁进行直接的电气或物理连接。该装置的输出将用作控制信号，该信号可用于调整泵的速度，以防止泵流入管道、左心室和上游血管系统中产生过大的负压。

DESCRIPTION (provided by applicant): Axial flow rotary blood pumps have been successfully introduced clinically to provide prolonged mechanical circulatory support, but these devices do not provide load-responsive mechanisms for adjusting pump performance to match venous return and changes in physiologic demand. Most of these devices operate at an adjustable fixed speed, and they have the potential to generate excessive suction pressures that can have serious consequences for the patient. A new device is proposed to monitor the inlet pressure in rotary blood pumps to improve their safety and efficacy. Conventional strain gauge transducers are subject to drift and have stability issues that make them unsuitable for long-term implantation. The proposed device employs a comparatively large displacement diaphragm in an elliptical cross-section conduit whose excursion is sensed by a planar transformer system operating at radio frequencies. There is no direct physical contact with the moving diaphragm. Unlike control algorithms that infer hemodynamic conditions at the pump inflow from parameters such as the motor current, the proposed device will enable the development of control systems that dynamically adjust pump speed to avoid excessive suction pressures and optimize pump blood flow. In essence this will make these devices operate similar to Starling's law devices in which the available blood at the inflow determines the pump output. In Phase I we will design the new inlet pressure sensor and evaluate its static and dynamic performance to evaluate its applicability for controlling a rotary blood pump. A demonstration of feasibility will consist of showing that the device accurately measures inlet conduit pressure and that it has a response time that will permit automatic speed control on a beat-by-beat or short-term averaged basis. PUBLIC HEALTH RELEVANCE The proposed device is an electromechanical component designed to measure pressure in the inlet conduit of a blood rotary pump in order to prevent excessive suction pressures. The device output will be referenced to intrathoracic pressure. It works by monitoring the deflection of an elliptical cross section elastomeric conduit in response to changes in its internal pressure. This deflection is measured using a planar transformer system operating at radio frequencies transparent to body tissues. No direct electrical or physical connection to the moving wall of the conduit is required. The output of the device will be usable as a control signal that may be employed to adjust the pump speed to prevent the development of excessive negative pressures in the pump inflow conduit, left ventricle, and upstream vasculature.