Factors that affect swallowing-related apnea times in humans.

The dynamics of deglutition were studied in relation to potential changes due to aging. Swallowing-related apnea time (SAT) was measured during "dry" and "wet" swallowing in 84 adults without dysphagia to examine if age-related variation of SAT corresponded to changes in deglutition dynamics due to aging and to determine possible significance. Swallowing movements were recorded using a transducer for measuring swallowing pressures. Respiratory flow rates during deglutition were measured with a heat-wave flowmeter as part of phonatory function testing system. Respiratory movements were recorded with a respiration pick-up band set at the diaphragm. Findings demonstrated that SAT did not change with aging but was prolonged in subjects over age 50 years. When topical anesthesia was omitted during study, SAT tended to be shorter during wet swallowing than during dry swallowing in all age groups. Statistically significant differences were observed between wet and dry swallowing SAT in subjects under the age of 39 years. When a topical anesthetic was applied to pharyngeal mucous membranes, SAT was prolonged. Finally, SAT results during wet swallowing determined in a anesthetized dog before and after topical anesthesia of the pharyngeal mucous membranes showed significant prolongation after topical anesthesia. These findings suggest that the sensation of the pharyngeal mucous membrane may be important in producing swallowing-related apnea and controlling its duration.