Otis D R, Johnson M, Pedley T J, Kamm R D
Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge 02139.
J Appl Physiol (1985). 1993 Sep;75(3):1323-33. doi: 10.1152/jappl.1993.75.3.1323.
A numerical model that simulates airway closure by liquid bridging during expiration has been developed. The effects of both surfactant and time-varying geometry have been included; the model determines the liquid layer flow resulting from a surface tension (Rayleigh) instability, and the computation traces the film's development to closure, yielding pressure, velocity, surface shape, and surfactant concentration distributions. It is found that surfactant is effective in retarding or eliminating liquid bridging through the reduction of the mean surface tension and the action of surface tension gradients. The former effect is also critical in minimizing the magnitude of the negative pressure in the liquid layer and thus presumably in reducing the tendency for airway compliant collapse.
已开发出一种数值模型，用于模拟呼气过程中液桥导致的气道闭合。该模型考虑了表面活性剂和随时间变化的几何形状的影响；模型确定了由表面张力（瑞利）不稳定性产生的液层流动，并通过计算追踪液膜发展至闭合的过程，得出压力、速度、表面形状和表面活性剂浓度分布。研究发现，表面活性剂通过降低平均表面张力以及表面张力梯度的作用，有效地延缓或消除了液桥现象。前一种效应对于使液层中的负压幅值最小化也至关重要，因此可能有助于降低气道顺应性塌陷的趋势。
