Vollkron Michael, Schima Heinrich, Huber Leopold, Benkowski Robert, Morello Gino, Wieselthaler Georg
Department of Cardiothoracic Surgery and Ludwig Boltzmann Institute for Cardiosurgical Research, Medical University of Vienna, Vienna, Austria.
J Heart Lung Transplant. 2005 Nov;24(11):1878-85. doi: 10.1016/j.healun.2005.02.004.
Axial blood pumps have been very successfully introduced into the arena of prolonged clinical support. However, they do not offer inherent load-responsive mechanisms for adjusting pumping performance to venous return and changes in physiologic requirements of the patient. To provide for these adjustments we developed an algorithm for demand-responsive pump control based on a reliable suction detection system.
A PC-based system that analyzes pump performance based on available flow, heart rate and short-term performance history was developed. The physician defines levels of "desired flow" at rest and during exercise, depending on heart rate. In case this desired flow cannot be maintained due to limited venous return, the maximal available flow level is determined from an analysis of the actual pump data (flow, speed and power consumption). An expert system continuously checks the flow signal for any indication of suction. Periodic speed variations then adapt pump performance to the patient's condition.
First, stability and functionality were proven under various settings in vitro. The algorithms were then tested in 15 patients in intensive care, in the standard ward, and during bicycle exercise. The system reacted properly to demand changes, at exercise level, in response to coughing and at various Valsalva maneuvers. Suction could also be successfully prevented during severe arrhythmia and in patients with critical cardiac geometry. Exercise tests showed decreases in pulmonary arterial pressure (-22 +/- 9.9%) and pulmonary capillary wedge pressure (-42 +/- 18.54%), and an increase in pump flow (19 +/- 9.5%) and workload (8 +/- 6.1%), all when compared with constant-speed pumping.
A closed-loop control system equipped with an expert system for reliable suction detection was developed that improves response to change in venous return for rotary pump recipients. The system was robust, stable and safe under a wide range of everyday living conditions.
轴流血泵已非常成功地应用于长期临床支持领域。然而，它们没有提供内在的负荷响应机制来根据静脉回流和患者生理需求的变化调整泵血性能。为了实现这些调整，我们基于可靠的吸力检测系统开发了一种按需响应泵控制算法。
开发了一种基于个人计算机的系统，该系统根据可用流量、心率和短期性能历史来分析泵的性能。医生根据心率定义静息和运动时的“期望流量”水平。如果由于静脉回流受限而无法维持该期望流量，则通过分析实际泵数据（流量、速度和功耗）来确定最大可用流量水平。一个专家系统持续检查流量信号是否有任何吸力迹象。然后，周期性的速度变化使泵的性能适应患者的状况。
首先，在体外的各种设置下证明了其稳定性和功能性。然后，该算法在15名重症监护患者、标准病房患者以及自行车运动期间进行了测试。该系统在运动水平、咳嗽时以及各种瓦尔萨尔瓦动作时对需求变化做出了正确反应。在严重心律失常患者和心脏几何形状异常的患者中也成功预防了吸力。运动测试显示，与恒速泵血相比，肺动脉压（-22±9.9%）和肺毛细血管楔压（-42±18.54%）降低，泵流量（19±9.5%）和工作量（8±6.1%）增加。
开发了一种配备用于可靠吸力检测的专家系统的闭环控制系统，该系统改善了旋转泵接受者对静脉回流变化的反应。该系统在广泛的日常生活条件下坚固、稳定且安全。
