Models of Surfactant Interactions in Pulmonary Mechanical Behavior

Wednesday, January 27, 1999 - 9:30am - 10:30am
Keller 3-180
Don Gaver (Naval Postgraduate School)
Pulmonary airway closure occurs in premature neonates suffering from respiratory distress syndrome (RDS). This disease occurs among infants who cannot provide an adequate quantity or quality of pulmonary surfactant. This substance is released by alveolar pneumocytes and serves to reduce the surface tension of the air liquid interface that coats the interior surfaces of the lung. In 1990, RDS afflicted approximately 24,000 infants in the United States and resulted in 12% mortality. With the advent of surfactant replacement therapy, RDS deaths have been reduced by 30-40%, but still remains the 4th leading cause of infant death in the United States. The investigations described in this talk will focus on investigations of surfactant physicochemical interactions in models of thin-film dynamics in the lung. Two aspects of surfactant physicochemical hydrodynamics and its influence on pulmonary mechanics will be emphasized. The first study investigates the importance of dynamic surface tension behavior in models of pulmonary airway reopening. Theoretical and experimental investigations demonstrate the importance of adsorption dynamics on airway reopening pressures and suggests an optimal adsorption behavior that may reduce reopening pressures while protecting the lung from airway closure. The second study investigates surfactant dynamics in models of an oscillating bubble, intended to mimic alveolar dynamics and a pulsating bubble surfactometer. We propose a multilayer model of surfactant dynamics which explains surfactant=92s ability to sustain ultra-low surface tensions upon interfacial compression, and accurately mimics pressure-volume hysteresis loops that are evident in experiments. This model suggests that the ability of surfactant to produce a multilayer is key to proper surfactant function.

Joint work with:
Melissa A. Krueger
Samir Ghadiali

Tulane University
Department of Biomedical Engineering
New Orleans, LA 70118