Compensatory mechanisms induced by high oropharyngeal airway resistance in rats.

Acid base balance changes were observed during 72 h following bilateral nasal obstruction in rats. Mouth breathing caused acute respiratory acidosis and marked aerophagia, leading to spontaneous death of the experimental animal 80 to 90 h postoperatively. Stenotic oropharyngeal airway, due to palatal-epiglottic approximation, is supposed to be responsible for respiratory insufficiency in the nose obstructed rats. The compensatory changes in respiratory mechanics caused by high oropharyngeal airway resistance, together with some possible reflex changes, may have caused either air swallowing or aspiration. As changes in acid base balance parameters did not show breakdown of the compensatory mechanisms during the first 72 h postoperatively, it is supposed that the increased air volume in stomach and guts, causing elevation of the diaphragm and paralytic ileus, contributed to the experimental animals' death.