Sensory stimulation, including stimulation with carbonated liquids, has been known to influence swallowing activity. The aim of this study is to determine the effect of sustained changes in the swallowing behavior of hospitalized patients without dysphagia using the cervical auscultatory recordings of swallowing sounds. The study participants were hospitalized older adults without dysphagia. The participants were asked to initially swallow water and then a carbonated beverage. The sustained effects of the carbonated beverage in relation to swallowing movements were evaluated by measuring the swallowing sounds at the following time periods: (1) immediately and (2) at 1 to 9 min with intervals of 2 min after swallowing the carbonated beverage. The swallowing sounds before and after swallowing the same volume of water were also measured and compared on a different day. Analysis was performed to calculate the time from a sound signal to the beginning of the swallowing sound. Significant shortening of the swallowing sound time of the late pharyngeal phase was observed up to 7 min after swallowing the carbonated beverage, except during the 3 min after swallowing. Shortening of the whole swallowing sound time was observed only immediately after swallowing the carbonated beverage. Regarding the shortening of the acoustic signal in the late pharyngeal period, the effect of cerebral excitability changes due to carbonic acid stimulation was considered.
Keywords: Carbonated beverages; Sensory stimulation; Sustained effect; Swallowing behavior; Swallowing sound.
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