Characterization of Pulmonary Circulation during Mechanical Ventilation

机械通气期间肺循环的特征

• 批准号: 13671580
• 负责人: OKAZAKI Naoto
• 金额: $ 1.41万
• 依托单位: Tottori University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13671580/
• 关键词: rabbit; isolated perfusion lung; electric circuit model; resonance circuit; pressure-volume curve; lognomal distribution; lower inflection point; 摘出還流肺; インピーダンス; 高速フーリェ変換; 人工換気; PEEP圧

This study was performed by simulating pulmonary circulation to the electric circuit model on the hypothesis that a lung has the function to restrain an energy loss such as the series and the parallel resonance in the altemating current, in addition to the merit explained by Windkessel theory (decrease of the flow resistance by pulsatile circulation). A characterization of pulmonary circulation was examined by fitting the pulmonary arterial input impedance of the isolated perfusion rabbit lung to the six-element lamp model. As a result, the maximum likelihood model was the combination of Landes model and Goldwyn-Watt's model, which was provided with a proximal and a peripheral segment, corresponding to the series and the parallel resonance circuit. It was speculated that the circulation was controlled with flow lead in the proximal segment and with pressure lead in the peripheral segment.And, new method to analyze the pressure volume curve (PV-curve) was examined. The fundamentally theory is following: we can estimate that the frequency distribution of the volume of alveoli obeys a normal distribution from the law of large numbers. On the other hand, considering the equation of continuity in the hollow sphere receiving extemal force (as lung), there are two solves at the cases of the uniform compression and the compressible process. Then, the volume function should be revealed as logarithmic pressure when the condition is a compressible fluid. Therefore, the alveoli volume distribution of PV-curve measured by a dynamical method has to be explained in the logarithmic nomal distribution. As a result plotting the volume ratio to total lung capacity on the probability graph paper of logarithmic normal distribution, two crossed linear lines are recognized. And this crossing point is the lower inflection point (LIP) of the PV-curve. These were inspected by this study.

本研究是通过将肺循环模拟到电路模型来进行的，假设除了由Windkessel理论解释的优点（通过脉动循环降低流动阻力）之外，肺还具有抑制能量损失（例如交变电流中的串联和并联谐振）的功能。通过将离体灌流兔肺的肺动脉输入阻抗拟合到六元灯模型来研究肺循环的特征。最大似然模型是Landes模型和Goldwyn-Watt模型的结合，该模型具有近端段和外围段，分别对应串联和并联谐振电路。推测近段采用流量导联控制循环，外周段采用压力导联控制循环，并探讨了分析压力容积曲线（PV曲线）的新方法。其基本原理是：根据大数定律，可以估计肺泡容积的频率分布服从正态分布。另一方面，考虑到空心球（如肺）在外力作用下的连续性方程，在均匀压缩和可压缩过程中有两种解。然后，当条件是可压缩流体时，体积函数应显示为对数压力。因此，用动力学方法测得的肺容积曲线的肺泡容积分布必须用对数正态分布来解释。将肺容积与肺总容量之比绘制在对数正态分布的概率图上，可识别出两条交叉的直线。这个交叉点是PV曲线的下拐点（LIP）。本研究对这些进行了检查。