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A theoretical study of surfactant and liquid delivery into the lung

A theoretical study of surfactant and liquid delivery into the lung Abstract 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 ∼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. pulmonary surfactant drug delivery surfactant replacement therapy respiratory distress syndrome Marangoni flow airway liquid surface tension dynamics pulmonary fluid mechanics Footnotes Address for reprint requests: D. Halpern, Dept. of Mathematics, Univ. of Alabama, Tuscaloosa, AL 35487. Present address of J. B. Grotberg: Biomedical Engineering, Univ. of Michigan, 3304 G.G. Brown, 2350 Hayward, Ann Arbor, MI 48109. Copyright © 1998 the American Physiological Society http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Applied Physiology The American Physiological Society

A theoretical study of surfactant and liquid delivery into the lung

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Publisher
The American Physiological Society
Copyright
Copyright © 2011 the American Physiological Society
ISSN
8750-7587
eISSN
1522-1601
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Abstract

Abstract 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 ∼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. pulmonary surfactant drug delivery surfactant replacement therapy respiratory distress syndrome Marangoni flow airway liquid surface tension dynamics pulmonary fluid mechanics Footnotes Address for reprint requests: D. Halpern, Dept. of Mathematics, Univ. of Alabama, Tuscaloosa, AL 35487. Present address of J. B. Grotberg: Biomedical Engineering, Univ. of Michigan, 3304 G.G. Brown, 2350 Hayward, Ann Arbor, MI 48109. Copyright © 1998 the American Physiological Society

Journal

Journal of Applied Physiology – The American Physiological Society

Published: Jul 1, 1998

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