Pediatric Circulatory Support

PediaFlow联盟正在开发一种混合流涡轮动力（连续流）心室辅助装置，该装置利用磁悬浮叶轮，能够产生0.3-1.5升/分钟（LPM）的血流，用于支持体重3-15 kg的婴儿和6个月以下的幼儿，具有最低的抗凝要求和最佳的生物相容性。 最初考虑了20多种设计变化，选择了三种泵拓扑结构进行进一步的设计改进和评估。三种设计（两种离心泵和一种混流泵）基于多组分目标函数进行判断，该目标函数考虑了几个标准，包括解剖学拟合、估计的生物相容性、产热和传热、磁悬浮悬浮液稳健性和可制造性。该评估导致选择混流式配置。 使用计算流体动力学改进设计，通过修改预测血流路径的几何形状，最大限度地减少流动引起的血液损伤。建立了一个血液流动路径的透明复制品，以通过流动可视化分析来验证计算机预测。 其他正在进行的工作集中在控制器开发、材料选择、生物相容性涂层应用、基于纳米技术的感染控制、套管设计以及血液动力学性能和细胞生物相容性的总体评估。 初始组件（图1、2）的制造和组装产生了最终的第一代泵设计（PediaFlow ™ GEN 1），其长度为51 mm，直径为28 mm，入口和出口导管直径为5 mm。质量约为100克。在0.5 LPM的标称流速下，产生110 mm Hg的压力上升，以及8，000 RPM的转子速度，轴功率约为0.9瓦，导致总效率估计为11%。

The PediaFlow consortium is developing a mixed-flow turbodynamic (continuous flow) ventricular assist device utilizing a magnetically levitated impeller capable of producing 0.3-1.5 liters per minute (LPM) of blood flow for supporting infants and small children weighing 3-15 kg up to 6 months with minimal anticoagulation requirement and optimal biocompatibility. Over 20 design variations were initially considered, with three pump topologies selected for further design refinement and evaluation. The three designs, two centrifugal and one mixed-flow pumps, were judged based on a multi-component objective function which factored several criteria including anatomic fit, estimated biocompatibility, heat generation and transfer, magnetically levitated suspension robustness, and manufacturability. This evaluation led to selection of the mixed-flow configuration. The design was improved using computational fluid dynamics to minimize flow-induced blood damage via modification of the geometry of the predicted blood flow path. The housing was modified to improve surgical fixation. A transparent replica of the blood flow path was built to perform validation of the computer predictions by flow visualization analyses. Other ongoing efforts are focused on controller development, materials selection, biocompatible coating application, nanotechnology based infection control, cannula design, and overall assessment of hemodynamic performance and cellular biocompatibility. Fabrication and assembly of initial components (Figures 1, 2) produced a finalized first generation pump design (PediaFlow¿ GEN1) that is 51 mm in length and 28 mm in diameter with 5 mm diameter inlet and outlet conduits. The mass is approximately 100 grams. At a nominal flow rate of 0.5 LPM, generating 110 mm Hg pressure rise, and 8,000 RPM rotor speed, the shaft power is approximately 0.9 Watts leading to an overall efficiency estimate of 11%.