Department of Physics, University of Warwick, Coventry CV4 7AL, UK.
Med Eng Phys. 2009 Nov;31(9):1118-33. doi: 10.1016/j.medengphy.2009.07.009. Epub 2009 Aug 20.
A multi-technique approach to modelling artificially ventilated patients on the adult general intensive care unit (ICU) is proposed. Compartmental modelling techniques were used to describe the mechanical ventilator and the flexible hoses that connect it to the patient. 3D CFD techniques were used to model flow in the major airways and a Windkessel style balloon model was used to model the mechanical properties of the lungs. A multi-compartment model of the lung based on bifurcating tree structures representing the conducting airways and pulmonary circulation allowed lung disease to be modelled in terms of altered V/Q ratios within a lognormal distribution of values and it is from these that gas exchange was determined. A compartmental modelling tool, Bathfp, was used to integrate the different modelling techniques into a single model. The values of key parameters in the model could be obtained from measurements on patients in an ICU whilst a sensitivity analysis showed that the model was insensitive to the value of other parameters within it. Measured and modelled values for arterial blood gases and airflow parameters are compared for 46 ventilator settings obtained from 6 ventilator dependent patients. The results show correlation coefficients of 0.88 and 0.85 for the arterial partial pressures of the O(2) and CO(2), respectively (p<0.01) and of 0.99 and 0.96 for upper airway pressure and tidal volume, respectively (p<0.01). The difference between measured and modelled values was large in physiological terms, suggesting that some optimisation of the model is required.
提出了一种多技术方法，用于对成人综合重症监护病房（ICU）上的人工通气患者进行建模。使用房室模型技术来描述呼吸机和将其连接到患者的柔性软管。使用 3D CFD 技术来模拟主要气道中的流动，并使用风箱式气球模型来模拟肺部的机械特性。基于代表传导气道和肺循环的二叉树结构的肺部多室模型允许根据改变的 V/Q 比在对数正态分布的范围内对肺部疾病进行建模，并且从这些比中确定气体交换。使用房室建模工具 Bathfp 将不同的建模技术集成到单个模型中。模型中的关键参数的值可以从 ICU 中的患者测量中获得，而敏感性分析表明模型对其内部其他参数的值不敏感。将 6 名依赖呼吸机的患者获得的 46 种呼吸机设置的动脉血气和气流参数的测量值和模型值进行比较。结果表明，O(2)和 CO(2)的动脉分压的相关系数分别为 0.88 和 0.85（p<0.01），上气道压力和潮气量的相关系数分别为 0.99 和 0.96（p<0.01）。测量值和模型值之间的差异在生理上很大，表明需要对模型进行一些优化。
