A theoretical study of surfactant and liquid delivery into the lung
A theoretical study of surfactant and liquid delivery into the lung
复制标题
DOI：
10.1152/jappl.1998.85.1.333
复制
发表时间：
1998-07-01
影响因子：
3.3
通讯作者：
Grotberg, JB
中科院分区：
文献类型：
--
作者：
Halpern, D;Jensen, OE;Grotberg, JB
一个计算研究的运输液体和不溶性表面活性剂通过肺气道，从气管远端的来源提供。考虑了四种不同的输送方式：1）滴注的丸剂可产生堵塞大气道的液体塞，但在机械通气期间被迫向外周输送; 2）丸剂在气道壁上产生沉积膜，该沉积膜来自液体塞输送或来自直接涂覆，其在重力的影响下通过最初的几个气道生成而排出; 3）在较小的气道中，表面活性剂种类形成由于表面张力梯度而扩散的表面层，即，Marangoni流动;和4）表面活性剂最终到达肺泡隔室，在那里它根据一级动力学被清除。预测了准稳态运输过程演变和随后输送剂量所需的时间。在相当快速的瞬变之后，在秒的数量级上，稳态运输发展并且由马兰戈尼流和肺泡动力学的相互作用支配。对于典型的第一剂量，总递送时间类似于24小时。数值解表明，过境和交货时间的强烈影响的强度预先存在的表面活性剂和气道网络的几何性质。随着预先存在的表面活性剂水平的升高，后续剂量的给药时间可能会显著增加。
A computational study is presented for the transport of liquids and insoluble surfactant through the lung airways, delivered from a source at the distal end of the trachea. Four distinct transport regimes are considered: 1) the instilled bolus may create a liquid plug that occludes the large airways but is forced peripherally during mechanical ventilation; 2) the bolus creates a deposited film on the airway walls, either from the liquid plug transport or from direct coating, that drains under the influence of gravity through the first few airway generations; 3) in smaller airways, surfactant species form a surface layer that spreads due to surface-tension gradients, i.e., Marangoni flows; and 4) the surfactant finally reaches the alveolar compartment where it is cleared according to first-order kinetics. The time required for a quasi-steady-state transport process to evolve and for the subsequent delivery of the dose is predicted. Following fairly rapid transients, on the order of seconds, steady-state transport develops and is governed by the interaction of Marangoni flow and alveolar kinetics. Total delivery time is similar to 24 h for a typical first dose. Numerical solutions show that both transit and delivery times are strongly influenced by the strength of the preexisting surfactant and the geometric properties of the airway network. Delivery times for follow-up doses can increase significantly as the level of preexisting surfactant rises.