Background and objective

The “Cardiac pump theory” and “Thoracic pump theory” are representative theories of cardiopulmonary resuscitation (CPR) mechanisms. Based on these theories, many studies on mathematical modeling have been performed to help understand hemodynamics during CPR. However, there are parts that do not yet properly reflect the physiology of CPR. Therefore, this study aims to develop a lumped parameter model of CPR that can more accurately reflect the current CPR physiology.

Methods

By adding compartments of the superior and inferior vena cava of the thoracic cavity to the existing CPR model, and the “Hybrid pump” mechanism was applied to simulate CPR. To compare the hemodynamics of the conventional CPR model and the developed CPR model, various conditions, such as active compression–decompression CPR with an impedance threshold valve device (ACD–CPR+ITV), head-up-tilt (HUT), and head-down-tilt (HDT), were simulated. The coronary perfusion pressure (CPP) was compared by modulating the compression ratio of the atrium and ventricle with the thoracic pump factor.

Results

The result for the comparison of coronary blood flow showed that the existing model is predominant in the compression phase, whereas the developed model is dominant in the relaxation phase. ACD–CPR + ITV results showed that the CPP decreased by 5 % in the existing model, and increased by about 46 % in the developed model, revealing a distinct hemodynamic difference between the two models. Likewise, as a result of comparing the hemodynamic differences of the two models according to the changes in tilt angle, the HUT showed similar trends, while the HDT showed slightly different results. The CPP varied accordingly with the ratio of the ventricular and atrial thoracic pump factor.

Conclusion

Comparison of the hemodynamics with the existing model by simulating various conditions showed that the developed CPR model reflects the CPR physiology better. The model suggests that the hemodynamics may vary depending on the ventricle and atrium compression ratio. This study may provide an important basis for helping understand various situations and patient-specific hemodynamic characteristics during CPR through in-depth research, such as patient-specific model and parameter optimization.

中文翻译：

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改良混合泵心肺复苏机制的数学模型

背景和目标

“心泵理论”和“胸泵理论”是心肺复苏（CPR）机制的代表理论。基于这些理论，已经进行了许多数学建模研究，以帮助了解 CPR 期间的血流动力学。但是，有些部分尚未正确反映 CPR 的生理学。因此，本研究旨在开发一种能够更准确地反映当前 CPR 生理学的 CPR 集总参数模型。

方法

通过在现有CPR模型中增加胸腔上腔静脉和下腔静脉的隔室，应用“混合泵”机制模拟CPR。为了比较传统 CPR 模型和开发的 CPR 模型的血流动力学，各种条件，例如主动压缩-减压 CPR 与阻抗阈值阀装置 (ACD-CPR+ITV)、抬头倾斜 (HUT) 和头部-下倾斜（HDT），进行了模拟。通过调节心房和心室的压缩比与胸泵因子来比较冠状动脉灌注压（CPP）。

结果

冠状动脉血流比较的结果表明，现有模型在压缩阶段占主导地位，而开发模型在松弛阶段占主导地位。ACD-CPR + ITV 结果显示，现有模型的 CPP 下降了 5%，而开发模型中的 CPP 增加了约 46%，揭示了两种模型之间明显的血流动力学差异。同样，根据倾斜角的变化比较两种模型的血流动力学差异，HUT 表现出相似的趋势，而 HDT 表现出略有不同的结果。CPP 随心室和心房胸泵因子的比值相应变化。

结论

通过模拟各种条件将血流动力学与现有模型进行比较表明，所开发的 CPR 模型更好地反映了 CPR 生理学。该模型表明，血流动力学可能因心室和心房压缩比而异。本研究可能通过深入研究，如患者特异性模型和参数优化，为帮助理解 CPR 期间的各种情况和患者特异性血流动力学特征提供重要依据。