Published ahead of print on February 5, 2004, doi:10.1164/rccm.200309-1283OC Am. J. Respir. Crit. Care Med., Volume 169, Number 9, May 2004, 1063-1069 A more recent version of this article appeared on May 1, 2004
Submitted on September 15, 2003 Regional Effects of Selective Pharyngeal Muscle Activation on Airway ShapeSamuel T Kuna1*1 Department of Medicine, Philadelphia Veterans Affairs Medical Center, Philadelphia, PA, USA; Pulmonary, Allergy and Critical Care Division, Department of Medicine, University of Pennsylvania, Center for Sleep and Respiratory Neurobiology, Philadelphia, PA, USA * To whom correspondence should be addressed. E-mail: skuna{at}mail.med.upenn.edu.
Pharyngeal airway fiberoptic imaging was performed in 10 decerebrate cats to determine the effect of selective pharyngeal muscle activation on airway shape. At intraluminal pressures from +6 to -6 cm H2O, maximum anteroposterior and lateral diameters were measured in the rostral oropharynx, caudal oropharynx, and velopharynx with and without bilateral stimulation of the medial hypoglossus, lateral hypoglossus, whole hypoglossus, glossopharyngeus, and pharyngeal branch of vagus nerves. At all 3 airway levels without nerve stimulation, the increase in diameter with increasing pressure was greater in the lateral than anteroposterior dimension. Stimulation of the hypoglossal and glossopharyngeus nerves caused greater increases in lateral than anteroposterior diameter in all 3 regions with different effects across nerves and regions. Stimulation of these 4 nerves frequently caused greater increases in both diameters as airway cross-sectional area was decreased by lowering airway pressure. Stimulation of the pharyngeal branch of vagus resulted in greater decreases in lateral than anteroposterior dimension in the caudal oropharynx and velopharynx especially as airway cross-sectional area was increased by increasing intraluminal pressure. The results indicate that selective activation of pharyngeal muscles in cats frequently results in greater changes in lateral than anteroposterior airway diameter and that these effects are dependent on airway region and cross-sectional area. Key words: hypoglossus nerve, glossopharyngeus nerve, vagus nerve, velopharynx, oropharynx
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