Department of Cardiac Surgery, Grosshadern Medical Center, Ludwig Maximilian University of Munich, Munich, Germany.
Institute of Medical and Polymer Engineering, Technical University of Munich, Garching, Germany.
Artif Organs. 2020 Mar;44(3):268-277. doi: 10.1111/aor.13557. Epub 2019 Sep 30.
Occurrence of microbubbles (MB) is a major problem during venoarterial extracorporeal life support (ECLS) with partially severe clinical complications. The aim of this study was to establish an in vitro ECLS setup for the generation and detection of MB. Furthermore, we assessed different MB elimination strategies. Patient and ECLS circuit were simulated using reservoirs, a centrifugal pump, a membrane oxygenator, and an occluder (modified roller pump). The system was primed with a glycerin solution of 44%. Three different revolution speeds (2500, 3000, and 3400 rpm) were applied. For MB generation, the inflow line of the pump was either statically or dynamically (15 rpm) occluded. A bubble counter was used for MB detection. The effectiveness of the oxygenator and dynamic bubble traps (DBTs) was evaluated in regard to MB elimination capacities. MB generation was highly dependent on negative pressure at the inflow line. Increasing revolution speeds and restriction of the inflow led to increased MB activity. The significant difference between inflow and outflow MB volume identified the centrifugal pump as a main source. We could show that the oxygenator's ability to withhold larger MB is limited. The application of one or multiple DBTs leads to a significant reduction in MB count and overall gas volume. The application of DBT can significantly reduce the overall gas volume, especially at high flow rates. Moreover, large MB can effectively be broken down for faster absorption. In general, the incidence of MBs is significantly dependent on pump speed and restriction of the inflow. The centrifugal pump was identified as a major source of MB generation.
微泡（MB）的出现是部分严重临床并发症的动静脉体外生命支持（ECLS）的一个主要问题。本研究的目的是建立一种用于产生和检测 MB 的体外 ECLS 装置。此外，我们评估了不同的 MB 消除策略。患者和 ECLS 回路使用储液器、离心泵、膜式氧合器和阻塞器（改良滚柱泵）进行模拟。该系统用 44%的甘油溶液进行预充。应用了三种不同的转速（2500、3000 和 3400 rpm）。为了产生 MB，泵的入口线要么被静态阻塞，要么被动态阻塞（15 rpm）。使用气泡计数器进行 MB 检测。评估了氧合器和动态气泡捕集器（DBT）的有效性，以确定其消除 MB 的能力。MB 的产生高度依赖于入口线的负压。增加转速和限制入口会导致 MB 活性增加。入口和出口 MB 体积之间的显著差异确定了离心泵是主要来源。我们可以证明，氧合器阻止更大 MB 的能力是有限的。应用一个或多个 DBT 会导致 MB 计数和总气体体积的显著减少。DBT 的应用可以显著降低总气体体积，尤其是在高流速下。此外，较大的 MB 可以有效地被分解，以便更快地吸收。一般来说，MB 的发生率明显取决于泵速和入口限制。离心泵被确定为 MB 产生的主要来源。
