IEEE Trans Biomed Eng. 2018 Jul;65(7):1630-1638. doi: 10.1109/TBME.2017.2759667. Epub 2017 Oct 5.
Vagus nerve stimulation (VNS) is a potential therapeutic approach in a number of clinical applications. Although VNS is commonly delivered in an open-loop approach, it is now recognized that closed-loop stimulation may be necessary to optimize the therapy. In this paper, we propose an original generic closed-loop control system that can be readily integrated into an implantable device and allows for the adaptive modulation of multiple VNS parameters.
The proposed control method consists of a state transition model (STM), in which each state represents a set of VNS parameters, and a state transition algorithm that optimally selects the best STM state, minimizing the error between an observed physiological variable and a given target value. The proposed method has been integrated into a real-time adaptive VNS prototype system and has been applied here to the regulation of the instantaneous heart rate, working synchronously with cardiac cycles. A quantitative performance evaluation is performed on seven sheep by computing classical control performance indicators. A comparison with a proportional-integral (PI) controller is also performed.
The STM controller presents a median mean square error, overshoot, and settling time, respectively, equal to 622.21 ms , 72.8%, and 7.5 beats.
The proposed control method yields satisfactory accuracy and time response, while presenting a number of benefits over classical PI controllers. It represents a feasible approach for multiparametric VNS control on implantable devices.
Closed-loop multiparametric stimulation may improve response and minimize side effects on current pathologies treated by VNS.
迷走神经刺激（VNS）是许多临床应用中的一种潜在治疗方法。尽管 VNS 通常采用开环方式提供，但现在已经认识到，为了优化治疗效果，闭环刺激可能是必要的。在本文中，我们提出了一种原始的通用闭环控制系统，该系统可以很容易地集成到植入式设备中，并允许自适应调节多个 VNS 参数。
所提出的控制方法由状态转移模型（STM）组成，其中每个状态代表一组 VNS 参数，以及一种状态转移算法，该算法通过最小化观察到的生理变量与给定目标值之间的误差，最优地选择最佳 STM 状态。该方法已集成到实时自适应 VNS 原型系统中，并应用于调节即时心率，与心脏周期同步工作。通过计算经典控制性能指标，对七只绵羊进行了定量性能评估。还与比例积分（PI）控制器进行了比较。
STM 控制器的均方根误差、超调量和调整时间分别为 622.21ms、72.8%和 7.5 拍。
所提出的控制方法具有令人满意的精度和时间响应，同时相对于经典 PI 控制器具有许多优势。它代表了一种在植入式设备上进行多参数 VNS 控制的可行方法。
闭环多参数刺激可以改善对 VNS 治疗的当前病症的反应并最小化副作用。
