Cassidy K J, Bull J L, Glucksberg M R, Dawson C A, Haworth S T, Hirschl R, Gavriely N, Grotberg J B
Department of Mechanical Engineering, Northwestern University, Evanston, Illinois 60208, USA.
J Appl Physiol (1985). 2001 May;90(5):1955-67. doi: 10.1152/jappl.2001.90.5.1955.
When a liquid is instilled in the pulmonary airways during medical therapy, the method of instillation affects the liquid distribution throughout the lung. To investigate the fluid transport dynamics, exogenous surfactant (Survanta) mixed with a radiopaque tracer is instilled into tracheae of vertical, excised rat lungs (ventilation 40 breaths/min, 4 ml tidal volume). Two methods are compared: For case A, the liquid drains by gravity into the upper airways followed by inspiration; for case B, the liquid initially forms a plug in the trachea, followed by inspiration. Experiments are continuously recorded using a microfocal X-ray source and an image-intensifier, charge-coupled device image train. Video images recorded at 30 images/s are digitized and analyzed. Transport dynamics during the first few breaths are quantified statistically and follow trends for liquid plug propagation theory. A plug of liquid driven by forced air can reach alveolar regions within the first few breaths. Homogeneity of distribution measured at end inspiration for several breaths demonstrates that case B is twice as homogeneous as case A. The formation of a liquid plug in the trachea, before inspiration, is important in creating a more uniform liquid distribution throughout the lungs.
在医学治疗过程中向肺气道内滴注液体时，滴注方法会影响液体在整个肺部的分布。为了研究液体传输动力学，将与不透射线示踪剂混合的外源性表面活性剂（固尔苏）滴注到垂直切除的大鼠肺的气管中（通气频率40次/分钟，潮气量4毫升）。比较了两种方法：对于A组，液体靠重力排入上气道，随后吸气；对于B组，液体最初在气管中形成一个液栓，随后吸气。使用微焦点X射线源和图像增强器、电荷耦合器件图像序列对实验进行连续记录。以每秒30帧的速度记录的视频图像被数字化并进行分析。对最初几次呼吸过程中的传输动力学进行统计量化，并遵循液体栓子传播理论的趋势。由强制气流驱动的液栓可在最初几次呼吸内到达肺泡区域。对几次呼吸末吸气时测量的分布均匀性表明，B组的均匀性是A组的两倍。吸气前在气管中形成液栓对于在整个肺部形成更均匀的液体分布很重要。
