Airway mechanics, gas exchange, and blood flow in a nonlinear model of the normal human lung
Airway mechanics, gas exchange, and blood flow in a nonlinear model of the normal human lung
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DOI：
10.1152/jappl.1998.84.4.1447
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发表时间：
1998-04-01
影响因子：
3.3
通讯作者：
Bidani, A
中科院分区：
文献类型：
--
作者：
Liu, CH;Niranjan, SC;Bidani, A
提出了一个综合气道/肺力学、肺血流和气体交换的正常人体强制肺活量（FVC）机动模型。它需要在操作过程中测量的胸膜内压作为输入。将选定的模型生成的输出变量与测量数据（口流量、肺体积变化以及口中过期的O-2和CO2浓度）进行比较。采用非线性参数估计算法改变选定的敏感模型参数，对数据进行合理的最小二乘拟合。本研究表明：1)呼吸模型的所有三个组成部分都是表征FVC操作的必要条件；2)肺血流速率的变化与肺泡压和胸膜内压的变化有关，影响气体交换和过期气体浓度的时间过程；3)在强制呼气时，必须包括可折叠的气道中间段以匹配气流。模型模拟表明，在强制呼气过程中，可折叠段和小气道对气流的阻力是显著的；它们的联合作用需要充分匹配吸气和呼气流量-容量循环。尽管这种集总单室模型存在局限性，但在正常受试者中获得了与气流和过期气体浓度测量结果的显著一致。此外，该模型提供了在FVC操作期间通气和灌注之间重要的动态相互作用的见解。
A model integrating airway/lung mechanics, pulmonary blood flow and gas exchange for a normal human subject executing the forced vital capacity (FVC) maneuver is presented. It requires as input the intrapleural pressure measured during the maneuver. Selected model-generated output variables are compared against measured data (flow at the mouth, change in lung volume, and expired O-2 and CO2 concentrations at the mouth). A nonlinear parameter-estimation algorithm is employed to vary selected sensitive model parameters to obtain reasonable least squares fits to the data. This study indicates that 1) all three components of the respiratory model are necessary to characterize the FVC maneuver; 2) changes in pulmonary blood flow rate are associated with changes in alveolar and intrapleural pressures and affect gas exchange and the time course of expired gas concentrations; and 3) a collapsible midairway segment must be included to match airflow during a forced expiration. Model simulations suggest that the resistances to airflow offered by the collapsible segment and the small airways are significant throughout forced expiration; their combined effect is needed to adequately match the inspiratory and expiratory flow-volume loops. Despite the limitations of this lumped single-compartment model, a remarkable agreement with airflow and expired gas concentration measurements is obtained for normal subjects. Furthermore, the model provides insight into the important dynamic interactions between ventilation and perfusion during the FVC maneuver.