Clinical Application of Bionic Baroreflex System

背景：我们开发了一种治疗中枢性压力感受性反射衰竭的仿生技术，并在手术中以直立性低血压的临床模型测试了其恢复动脉压(AP)的效果。方法和结果：仿生压力反射系统(BBS)是一个由计算机控制的负反馈系统，通过放置在下胸髓水平的硬膜外导管，感知AP并自动计算刺激交感神经的脉冲串的频率(STM)。根据一种经典的反馈控制理论，即带比例和积分增益因子的反馈校正，设计了一种BBS的运算规则。我们首先用白噪声系统辨识方法辨识了12例七氟醚麻醉颈椎骨科手术患者的STM到AP的传递函数，然后通过数值模拟确定反馈校正因子，使BBS能够快速稳定地衰减AP上的外部干扰。在21例直立性低血压的临床模型中检验了设计的BBS的性能。在没有实施BBS的情况下，大腿止血带的突然放气使AP在10秒内下降了17±3毫米汞，在50秒内下降了25±2毫米汞。在BBS实时执行过程中，放气后10秒、50秒、100秒时AP分别下降9±2、1±2、0±1。结论：人工压力反射系统仿生技术适用于人体。

Background : We developed a bionic technology for the treatment of central baroreflex failure, and tested its efficacy in restoration of arterial pressure(AP) against a clinical model of orthostatic hypotension during surgery.Methods and Results : The bionic baroreflex system(BBS) was a negative feedback system controlled by a computer, which sensed AP and automatically computed the frequency (STM) of a pulse train to stimulate sympathetic nerves through an epidural catheter placed at the level of lower thoracic spinal cord. According to a classical feedback control theory, i.e., feedback correction with proportional and integral gain factors, we designed an operational rule for the BBS. We first identified the transfer function from STM to AP by a white-noise system-identification method in 12 sevoflurane-anesthetized patients who underwent an orthopedic surgery of cervical vertebrae, and then determined the feedback correction factors with a numerical simulation to enable the BBS to quickly and stably attenuate an external disturbance on AP. The performance of the designed BBS was examined in a clinical model of orthostatic hypotension (n=21). Without the implementation of the BBS, a sudden deflation of the thigh tourniquet dropped AP by 17±3 mmHg in 10 sec and by 25±2 mmHg in 50 sec. During real-time execution of the BBS, on the other hand, the fall in AP was 9±2 mmHg at 10 sec and 1±2 mmHg at 50 sec, and 0±1 mmHg at 100 sec after the deflation.Conclusions : The bionic technology for the artificial baroreflex system would be applicable to humans.