Cardio-Respiratory Engineering and Technology Laboratory (CREATElab), Department of Mechanical and Aerospace Engineering, Monash University, Melbourne, VIC, Australia.
Cardio-Respiratory Engineering and Technology Laboratory (CREATElab), Department of Mechanical and Aerospace Engineering, Monash University, Melbourne, VIC, Australia.
Comput Methods Programs Biomed. 2024 Jun;250:108186. doi: 10.1016/j.cmpb.2024.108186. Epub 2024 Apr 18.
Venovenous Extracorporeal Membrane Oxygenation (VV ECMO) provides respiratory support to patients with severe lung disease failing conventional medical therapy. An essential component of the ECMO circuit are the cannulas, which drain and return blood into the body. Despite being anchored to the patient to prevent accidental removal, minor cannula movements are common during ECMO. The clinical and haemodynamic consequences of these small movements are currently unclear. This study investigated the risk of thrombosis and recirculation caused by small movements of a dual lumen cannula (DLC) in an adult using computational fluid dynamics.
The 3D model of an AVALON Elite DLC (27 Fr) and a patient-specific vena cava and right atrium were generated for an adult patient on ECMO. The baseline cannula position was generated where the return jet enters the tricuspid valve. Alternative cannula positions were obtained by shifting the cannula 5 and 15 mm towards inferior (IVC) and superior (SVC) vena cava, respectively. ECMO settings of 4 L/min blood flow and pulsatile flow at SVC and IVC were applied. Recirculation was defined as a scalar value indicating the infused oxygenated blood inside the drainage lumen, while thrombosis risk was evaluated by shear stress, stagnation volume, washout, and turbulent kinetic energy.
Recirculation for all models was less than 3.1 %. DLC movements between -5 to 15 mm increased shear stress and turbulence kinetic energy up to 24.7 % and 11.8 %, respectively, compared to the baseline cannula position leading to a higher predicted thrombosis risk. All models obtained a complete washout after nine seconds except for when the cannula migrated 15 mm into the SVC, indicating persisting stasis and circulating zones.
In conclusion, small DLC movements were not associated with an increased risk of recirculation. However, they may increase the risk of thrombosis due to increased shear rate, turbulence, and slower washout of blood. Developing effective cannula securement devices may reduce this risk.
静脉-静脉体外膜肺氧合（VV ECMO）为常规药物治疗无效的严重肺部疾病患者提供呼吸支持。ECMO 回路的一个重要组成部分是引流和回输血液的插管。尽管插管被固定在患者身上以防止意外拔出，但 ECMO 过程中插管会发生轻微移动。目前尚不清楚这些小的移动对临床和血液动力学的影响。本研究通过计算流体动力学方法研究成人双腔插管（DLC）轻微移动引起的血栓形成和再循环的风险。
根据 ECMO 患者的情况，生成 AVALON Elite DLC（27 Fr）和特定患者下腔静脉和右心房的三维模型。基线插管位置设定为回流通路射流进入三尖瓣的位置。通过将插管分别向下方（下腔静脉）和上方（上腔静脉）移动 5mm 和 15mm，得到替代插管位置。以 4L/min 的血流量和 SVC 与 IVC 的脉动血流设置 ECMO。再循环定义为指示引流腔内部输注的含氧血液的标量值，而血栓形成风险则通过剪切应力、停滞体积、冲洗和湍流动能来评估。
所有模型的再循环均小于 3.1%。与基线插管位置相比，DLC 在-5 至 15mm 之间的移动会使剪切应力和湍流动能分别增加 24.7%和 11.8%，导致预测的血栓形成风险增加。除了插管向 SVC 移动 15mm 时，所有模型在 9 秒后均获得完全冲洗，表明仍存在停滞区和循环区。
总之，DLC 的小移动与再循环风险增加无关。然而，由于剪切速率、湍流和血液冲洗速度减慢，它们可能会增加血栓形成的风险。开发有效的插管固定装置可能会降低这种风险。
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