Department of Biomedical Engineering, University of Iowa, Iowa City, IA, 52242, USA.
Section of Pediatric Cardiac Surgery, Duke University Medical Center, Durham, NC, USA.
Ann Biomed Eng. 2021 Dec;49(12):3636-3646. doi: 10.1007/s10439-021-02878-w. Epub 2021 Oct 27.
Oxygenator thrombosis during extracorporeal membrane oxygenation (ECMO), is a complication that necessitates component replacement. ECMO centers monitor clot burden by intermittent measurement of pressure drop across the oxygenator. An increase in pressure drop at a preset flow rate suggests an increase in resistance/clot formation within the oxygenator. This monitoring method comes with inherent disadvantages such as monitoring gaps, and increased risk of air embolism and infection. We explored utilizing flow measurement, which avoids such risks, as an indicator of ECMO circuit obstructions. The hypothesis that flow rate through a shunt tube in the circuit will increase as distal resistances in the circuit increases was tested. We experimentally simulated controlled levels of oxygenator obstructions using glass microspheres in an ex vivo veno-venous ECMO circuit and measured the change in shunt flow rate using over the tube ultra-sound flow probes. A mathematical model was also used to study the effect of distal resistances in the ECMO circuit on shunt flow. Results of both the mathematical model and the experiments showed a clear and measurable increase in shunt flow with increasing levels of oxygenator obstruction. Therefore, flow monitoring appears to be an effective non-contact and continuous method to monitor for obstruction during ECMO.
体外膜肺氧合 (ECMO) 过程中的氧合器血栓是一种需要更换部件的并发症。ECMO 中心通过间歇性测量氧合器跨压来监测血栓负荷。在预设流量下，压降增加表明氧合器内的阻力/血栓形成增加。这种监测方法存在固有缺点，例如监测间隙、空气栓塞和感染风险增加。我们探讨了利用流量测量作为 ECMO 回路阻塞的指标，这种方法避免了这些风险。我们假设，随着回路中远端阻力的增加，回路中的分流管中的流量将增加。我们使用体外静脉-静脉 ECMO 回路中的玻璃微球实验模拟了受控水平的氧合器阻塞，并使用管上超音波流量探头测量了分流流量的变化。还使用了数学模型来研究 ECMO 回路中远端阻力对分流流量的影响。数学模型和实验的结果都表明，随着氧合器阻塞程度的增加，分流流量明显且可测量地增加。因此，流量监测似乎是一种有效的非接触式和连续监测 ECMO 过程中阻塞的方法。
