A system to monitor the inlet pressure of rotary blood pumps

描述（由申请人提供）：轴流旋转血泵已成功地在临床上引入，以提供长时间的机械循环支持，但这些设备不提供负载响应机制来调节泵的性能以匹配静脉回流和生理需求的变化。这些装置大多以可调节的固定速度运行，它们有可能产生过大的吸入压力，这可能对患者造成严重后果。为了提高旋转血泵的安全性和有效性，提出了一种新的旋转血泵入口压力监测装置。传统的应变传感器容易漂移，并且存在稳定性问题，不适合长期植入。所提出的装置在椭圆横截面导管中采用相对大位移膜片，其偏移由在无线电频率下工作的平面变压器系统感测。与移动的隔膜没有直接的物理接触。与从电机电流等参数推断泵流入血流动力学条件的控制算法不同，该装置将使动态调节泵速的控制系统得以发展，以避免吸入压力过大并优化泵血流量。从本质上讲，这将使这些装置的工作原理类似于斯塔林定律装置，即流入处的可用血液决定泵的输出。在第一阶段，我们将设计新的进口压力传感器，并评估其静态和动态性能，以评估其控制旋转血泵的适用性。可行性论证将包括展示该设备准确测量进口管道压力，并具有响应时间，允许在逐拍或短期平均的基础上进行自动速度控制。与公共卫生相关的拟议装置是一种机电组件，设计用于测量血液旋转泵入口管道中的压力，以防止吸入压力过大。设备输出将参考胸内压。它的工作原理是监测椭圆截面弹性管道在响应其内部压力变化时的挠度。这种偏转是用一个平面变压器系统在对身体组织透明的射频下工作来测量的。不需要直接电或物理连接到导管的移动壁。该装置的输出将可用作控制信号，可用于调节泵的速度，以防止在泵的流入管道、左心室和上游血管系统中产生过度的负压。

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.