Effect of carbonation and thickening on voluntary swallow in healthy humans

Liquid modification is a widely established strategy of treatment for patients with dysphagia. The modification of liquid particularly by thickening or carbonation is a common approach to promote safe swallowing.

This study sought to investigate how carbonated and/or thickened water modulates swallowing behaviours during swallowing in healthy young individuals.

Thirty-one healthy volunteers (9 men, 22 women; mean age ± standard deviation [SD], 25.7 ± 6.2 years) were instructed to swallow 20 mL of water, carbonated water and carbonated juice with and without added thickening agent. Electromyograms (EMGs) of the suprahyoid (S-hyo) muscles were recorded to evaluate swallowing behaviours. Obtained S-hyo EMG bursts was analysed using the following outcome parameters: onset latency, the time between swallowing que to onset of EMG burst; rising time and falling time, defined as the time between onset and peak, and between peak and offset, respectively; duration, defined as the time between onset and offset of EMG burst; and area integral value under the waveform.

Effects of thickening demonstrated the extended onset latency, EMG burst duration including falling time and the larger area of EMG in thickened liquid compared to thin liquid, but there was not much difference between thin and thickened carbonated liquids. Carbonation significantly decreased the duration including falling time for thickened but not for thin liquids.

Patients with dysphagia can benefit from use of carbonated or thickened water while the effects on swallowing physiology may differ between carbonation and thickening.