非容积依赖性呼吸力学参数的估计及敏感度分析(英文)

Estimation and Sensitivity Analysis of Volume-Independent Parameters in Pulmonary Mechanics

呼吸力学参数是反映呼吸系统力学特性的重要生理指标,呼吸力学参数测量对临床医学以及特种劳动作业人员的健康鉴定及医学选拔均有重要意义。应用呼吸力学模型描述呼吸活动过程中呼吸驱动压P(t),呼吸流率V(t)以及肺容积V(t)之间的关系是呼吸力学参数测量与估计的理论基础。由于肺弹性系数、气道阻力对肺容积的依赖性,反映P(t)、V(t)、V(t)之间关系的呼吸力学模型应是非线性模型。然而,以往文献报道的呼吸力学模型大都为线性模型,应用线性模型估计呼吸力学参数仅在肺容积小范围变化时是有效的。根据呼吸力学原理,本文作者得到以下非线性呼吸力学模型:P(t)=(γ/V(t)+β)V(t)+σln(Vmax-V(t))+μ(Ⅰ)P(t)=(α/V(t)V(t)+σln(Vmax-V(t))+μ(Ⅱ)模型中,参数γ,β分别反应外周及中心气道阻力,α反映集总气道阻力;σ、μ反映肺弹性特性。数值仿真及参数估计敏感度分析结果表明:(1)模型(Ⅰ)中,γ、β参数估计的准确度较低,σ、μ参数估计的准确度较高;(2)模型(Ⅱ)中,α参数估计的准确度高于模型(Ⅰ)中γ参数估计的准确度;(3)两个模型中,肺弹性参数估计的准确度基本一致且均高于气道阻力参数估计的准确度。实际测量了8名健康被试者深吸气时的食道压力,呼吸流率及肺容积变化。用本文得到的非线性呼吸力学模型拟合实验数据,用最小二乘法估计模型中的非容积依赖性呼吸力学参数。结果表明,本文作者建立的模型可反映呼吸驱动压,呼吸流率及肺容积之间的关系。模型(Ⅰ)中,γ、β的变异系数大于σ、μ的变异系数;模型(Ⅱ)中,α的变异系数亦大于σ、μ的变异系数;模型(Ⅱ)中α的变异系数小于模型(Ⅰ)中γ、β的变异系数。以上结果与参数估计敏感度的理论分析相符。

In this paper two nonlinear models of pulmonary mechanics have beenput forward to represent the dynamic relationship of transpulmonary pressure to respiratoryflow rate and lung volume.Parameters in the models reflect the airway resistive state andthe elasticity of the lung,respectively.Simulation study and sensitivity analysis showed thatthe estimates of lung elastic parameters were more precise than that of airway resistance pa-rameters.Respiratory flow rate,esophageal pressure and lung volume were measured in 8healthy male subjects during deep respiratory maneuver.Parameters in the models were esti-mated by a least square fitting method.The results showed a good consistency of the sensi-tivity analysis with parameter estimation.