Effects of a synthetic lung surfactant on pharyngeal patency in awake human subjects

Van der Touw, T., A. B. H. Crawford, and J. R. Wheatley.Effects of a synthetic lung surfactant on pharyngeal patency inawake human subjects. J. Appl.Physiol. 82(1): 78-85, 1997.We examined theeffects of separate applications of saline and a synthetic lungsurfactant preparation (Surf; Exosurf Neonatal) into the supraglotticairway (SA) on the anteroposterior pharyngeal diameter(D_ap) and theairway pressures required to close (Pcl) and reopen (Pop) theSA in five awake normal supine subjects. D_ap, Pcl, and Popwere determined during lateral X-ray fluoroscopy and voluntary glotticclosure when pressure applied to the SA lumen was decreasedfrom 0 to 20 cmH₂O and thenincreased to +20 cmH₂O. After Surfapplication and relative to control,D_ap was largerfor most of the applied pressures, Pcl decreased (12.3 ± 1.9 to 18.7 ± 0.9 cmH₂O;P < 0.01), Pop decreased (13.4 ± 1.9 to 6.0 ± 3.4 cmH₂O;P < 0.01), and genioglossus electromyographic activity did not change (P > 0.05).Saline had no effect. These observations suggest that pharyngealintraluminal surface properties are important in maintaining pharyngealpatency. We propose that surfactants enhance pharyngeal patency byreducing surface tension and adhesive forces acting on intraluminal SAsurfaces.