Technical Indicators to Evaluate the Degree of Large Clot Formation Inside the Membrane Fiber Bundle of an Oxygenator in an In Vitro Setup
Technical Indicators to Evaluate the Degree of Large Clot Formation Inside the Membrane Fiber Bundle of an Oxygenator in an In Vitro Setup
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DOI：
10.1111/aor.13343
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发表时间：
2019-02-01
影响因子：
2.4
通讯作者：
Arens, Jutta
中科院分区：
文献类型：
--
作者：
Kaesler, Andreas;Hesselmann, Felix;Arens, Jutta
ECMO期间最常见的技术并发症是凝块形成。膜式氧合器内的大凝块降低了有效膜表面积，因此降低了气体转移能力，并限制了通过器械的血流，导致膜式氧合器压降（dpMO）增加。血栓形成事件的原因是多方面的，并且具有高度的患者特异性。ECMO期间氧合器内血栓的形成通常是不可预测的，并且仍然是一个未解决的问题。根据患者治疗后从器械中提取的CT数据，文献中充分记录了Maquet Quadrox-i成人氧合器的凝块尺寸和位置。基于这些数据，本研究旨在研究大凝块对纯技术参数的影响，例如，dpMO和气体转移。因此，将医用级硅胶注射到器械的纤维束中，以复制大凝块的位置和尺寸。根据ISO 7199，共对6件器械进行了体外试验，硅胶凝块体积为0、30、40、50、65和85 mL。通过在器械前后采集血液以及在血液流速为0.5、2.5和5.0 L/min时在器械出口处采集废气来测量气体转移。监测器械前后压力以计算不同血液流速下的dpMO。发现dpMO是一个可靠的参数，仅在已经晚期的“凝血阶段”中指示大凝块。“然而，废气中的二氧化碳浓度被发现对即使是小的凝块尺寸和低血流量也很敏感。在ECMO治疗期间，可以连续监测废气CO2浓度，对患者没有任何风险，以提供关于氧合器耐久性的额外信息。这可能有助于在ECMO期间检测膜式氧合器内的凝块形成和生长，即使dpMO的增加保持适度。
The most common technical complication during ECMO is clot formation. A large clot inside a membrane oxygenator reduces effective membrane surface area and therefore gas transfer capabilities, and restricts blood flow through the device, resulting in an increased membrane oxygenator pressure drop (dpMO). The reasons for thrombotic events are manifold and highly patient specific. Thrombus formation inside the oxygenator during ECMO is usually unpredictable and remains an unsolved problem. Clot sizes and positions are well documented in literature for the Maquet Quadrox-i Adult oxygenator based on CT data extracted from devices after patient treatment. Based on this data, the present study was designed to investigate the effects of large clots on purely technical parameters, for example, dpMO and gas transfer. Therefore, medical grade silicone was injected into the fiber bundle of the devices to replicate large clot positions and sizes. A total of six devices were tested in vitro with silicone clot volumes of 0, 30, 40, 50, 65, and 85 mL in accordance with ISO 7199. Gas transfer was measured by sampling blood pre and post device, as well as by sampling the exhaust gas at the devices' outlet at blood flow rates of 0.5, 2.5, and 5.0 L/min. Pre and post device pressure was monitored to calculate the dpMO at the different blood flow rates. The dpMO was found to be a reliable parameter to indicate a large clot only in already advanced "clotting stages." The CO2 concentration in the exhaust gas, however, was found to be sensitive to even small clot sizes and at low blood flows. Exhaust gas CO2 concentration can be monitored continuously and without any risks for the patient during ECMO therapy to provide additional information on the endurance of the oxygenator. This may help detect a clot formation and growth inside a membrane oxygenator during ECMO even if the increase in dpMO remains moderate.