Journal of Applied Physiology

Effect of intra-alveolar fluid on pulmonary surface tension properties

John W. C. Johnson, S. Permutt, John H. Sipple, El Sayed Salem


In 17 anesthetized dogs, 50–150 ml of isotonic saline or human amniotic fluid were instilled into a degassed lobe and after 2–6 hr of spontaneous or artificial ventilation, the lungs were excised. Static pressure-volume and extract surface tension values were then determined on a fluid- and a nonfluid-instilled lobe from each animal. When compared with nonfluid-instilled lobes the fluid-instilled lobes were found to have proportionately smaller volumes at maximum inflation (P < .02) and during deflation (P < .001) as well as regional areas with higher surface tension properties (P < .001). It is proposed that the pressure-volume studies may furnish a useful means of assessing the anatomical extent of alterations in lung surface tension. There was a significant negative correlation between maximum inflation volumes and maximum surface tensions (P < .001) as well as between the volumes during deflation and the minimum surface tensions (P < .001). It is concluded that intra-alveolar fluid may inactivate or displace the surface-active material from the alveolar lining membrane.

amniotic fluid; lung pressure-volume studies; lung surfactant

Submitted on April 11, 1963