Brain and behavioral effects of swallowing carbonated water on the human pharyngeal motor system

Chemical stimulation of the swallowing network with carbonation and citric acid has been investigated, showing potential benefits on swallowing of dysphagic patients. Despite this, the underlying mechanisms for these effects are not fully understood. Here we investigated the effects of 5 ml liquid bolus swallows of carbonated, citric acid, and still water on a swallowing reaction-time tasks paradigm in 16 healthy adults (8 male, mean age 33 ± 3.7 yr, protocol 1). We then investigated the net effects of “sensory bolus interventions” (40 repeated swallows every 15 s) of the three different liquid boluses on corticobulbar excitability, as examined with single-pulse transcranial magnetic stimulation (TMS) in 16 participants (8 female, mean age 33 ± 3.7 yr, protocol 2). The findings showed that a larger number of correctly timed swallows (within a predetermined time window) was accomplished mainly with carbonated liquids ( z = −2.04, P = 0.04 vs. still water, protocol 1). Both carbonated and citric acid liquid interventions with 40 swallows increased corticobulbar excitability of the stronger pharyngeal projection, suggesting a similar modulatory pathway for the effects on swallowing. However, carbonation showed superiority ( P = 0.04, F = 4.75, 2-way ANOVA), with the changes lasting up to 60 min following the intervention. These results hold significance for future further and in-depth physiological investigations of the differences between different stimuli on swallowing neural network.

Experimental study in the Na2O–CaO–MgO–Al2O3–SiO2–CO2 system at 3 GPa: the effect of sodium on mantle melting to carbonate-rich liquids and implications for the petrogenesis of silicocarbonatites

Melt compositions in equilibrium with peridotite assemblages were determined in the analogue system Na2O–CaO–MgO–Al2O3–SiO2–CO2 at 3 GPa with Ca/Ca + Mg = 0.56–0.43 and up to 6 wt.% Na2O. There is a greater compositional range generated isobarically over a larger temperature interval than in a sodium-absent system: increasing sodium content drives liquids to compositions with lower CaO and higher SiO2 concentrations. A positive correlation between silica and Na2O content of liquids produced at constant temperature is due to the depolymerization of silicate tetrahedra in the presence of monovalent cations, as in the volatile-free system. Liquids with Na2O >6 wt.% occur in association with wehrlites as the composition of diopsidic pyroxene expands towards enstatite with addition of Na2O, decreasing the orthopyroxene content of peridotite. The orthopyroxene-out curve intersects an enriched mantle solidus at 3 GPa where near-solidus liquids have Na2O = 7 1.5 wt.%. Sodium partitioning between a metaluminous liquid and clinopyroxene follows the jadeite partitioning models calculated for the dry silicate system but sodium partitions into peralkaline carbonated liquids as both the pyroxene and the carbonate molecules. The peralkaline liquids generated are essentially carbonated silicate melts that are analogous to silica-bearing carbonatites and silicocarbonatites from a range of possible metasomatized mantle sources.

Videoradiographic analysis of how carbonated thin liquids and thickened liquids affect the physiology of swallowing in subjects with aspiration on thin liquids

Purpose: To analyze how carbonated thin liquids affected the physiology of swallowing in dysphagic patients. Material and Methods: 40 patients were analyzed; 36 were neurologically impaired. During a therapeutic videoradiographic swallowing examination the patients had to swallow liquids with the following consistencies three times: thin, thickened and carbonated. The liquids were given in doses of 3 × 5 ml. The swallows were analyzed regarding penetration/aspiration, pharyngeal transit time and pharyngeal retention. Results: Significant difference was found regarding penetration/aspiration when comparisons were made between thin liquid and carbonated thin liquid ( p<0.0001). Carbonated liquid reduced the penetration to the airways. The comparison between thin liquid and thickened liquid ( p<0.0001) showed significant less penetration with thickened liquids. Pharyngeal transit time was reduced both when comparing thin liquid with thin carbonated liquid ( p<0.0001) and thickened liquid ( p<0.0001). Pharyngeal retention was significantly reduced ( p<0.0001) with carbonated thin liquid compared to thickened liquid. The comparison of thin liquids and carbonated thin liquids showed p = 0.0013, thin and thickened liquids p = 0.0097. Conclusions: Carbonated liquids reduced penetration/aspiration into the airways, reduced pharyngeal retention and pharyngeal transit time became shorter. Therefore, carbonated liquids are a valuable treatment option for patients with penetration/aspiration. Thickened liquids may still be an option for patients who cannot tolerate carbonated liquids and liquids with this consistency are safer than thin liquids.