Examining the role of carbonation and temperature on water swallowing performance: a swallowing reaction-time study.

Various therapeutic approaches for dysphagia management are based on modifications of bolus properties to change swallowing biomechanics and increase swallowing safety. Limited evidence exists for the effects of carbonation and bolus temperature on swallowing behavior. Here, we investigated the effects of carbonation and temperature on swallowing behavior using a novel automated and complex swallowing reaction time task via pressure signal recordings in the hypopharynx. Healthy participants (n = 39, 27.7±5 years old) were randomized in two different experiments and asked to perform 10 normal-paced swallows, 10 fast-paced swallows, and 10 challenged swallows within a predetermined time-window of carbonated versus still water (experiment 1) and of cold (4 °C) versus hot (45 °C) versus room temperature (21 °C) water (experiment 2). Quantitative measurements of latencies and percentage of successful challenged swallows were collected and analyzed nonparametrically. An increase in successfully performed challenged swallowing task was observed with carbonated water versus still water (P = 0.021), whereas only cold water shortened the latencies of normally paced swallows compared with room (P = 0.001) and hot (P = 0.004) temperatures. Therefore, it appears that chemothermal stimulation with carbonation and cold are most effective at modulating water swallowing, which in part is likely to be driven by central swallowing afferent activity.