Mechanical properties of the passive pharynx in Vietnamese pot-bellied pigs. I. Statics.
The static mechanical properties of the passive pharynx were investigated in Vietnamese pot-bellied pigs by using an isolated upper airway preparation. During general anesthesia and neuromuscular blockade, cross-sectional area (A) of the pharynx was measured while airway pressure (Paw) was held at various pressures in the absence of airflow. The static A-Paw relationship was measured during application of 0, 1, and 2 cm of caudal tracheal displacement. Relative to humans, closing pressures (Pclose) of the pig pharynx were very low (-15 to -35 cmH(2)O). Tracheal displacement significantly decreased compliance of the hypopharynx (from 0.074 +/- 0.02 cm(2)/cmH(2)O with no displacement to 0.052 +/- 0.01 cm(2)/cmH(2)O with 2 cm of displacement) and decreased Pclose of the oropharynx (from -18.2 +/- 9.9 cmH(2)O to -24.1 +/- 10.5 and -28.7 +/- 12.3 cmH(2)O with 1 and 2 cm of displacement, respectively). Tracheal displacement did not affect A of the pharyngeal segments. In conclusion, tracheal displacement decreased collapsibility of the passive pharynx. The pharynx of the pot-bellied pig is structurally more resistant to collapse than the human pharynx.
Tuck
Stephanie A
SA
Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada T2N 4N1.
Remmers
John E
JE
D019412:Anatomy, Cross-Sectional; D000818:Animals; D001696:Biomechanical Phenomena; D003187:Compliance; D004724:Endoscopy; D005260:Female; D007013:Hypopharynx / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D010614:Pharynx / Q000033:anatomy & histology / Q000502:physiology*; D011312:Pressure; D013552:Swine; D013556:Swine, Miniature / Q000033:anatomy & histology / Q000502:physiology*; D014132:Trachea / Q000502:physiology