Influence of Acid Swallows on the Dynamics of the Upper Esophageal Sphincter.
Simone Miller, Martin Ptok, Michael Jungheim
PMID 32886255WHAT IT FOUND
Swallowing very acidic water (pH 1.8) prolonged the time for the upper esophageal sphincter to return to rest, averaging 12.67 seconds, versus 8.69 seconds for neutral water. pH 3 and pH 5 did not show this change in healthy volunteers.
Key findings
01Swallowed pH 1.8 boli produced the longest mean restitution time, 12.67 seconds (SD ± 7.03 seconds), compared with 8.69 seconds (SD ± 2.72 seconds) for pH 7, 7.56 seconds (SD ± 2.23 seconds) for pH 3, and 7.29 seconds (SD ± 2.55 seconds) for pH 5.
02The pH 1.8 restitution time was higher than each other pH value, while pH 3 and pH 5 did not show a statistically significant difference from pH 7.
03Oscillations, prolonged high-pressure intervals in the upper esophageal sphincter during restitution, occurred in 69% of pH 1.8 swallows, 13% of pH 3 swallows, 6% of pH 5 swallows, and 13% of pH 7 swallows.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study was done in ten healthy volunteers without dysphagia, esophageal disease, or reflux, so it does not show what happens in patients with swallowing or reflux problems. The order of bolus acidity was not randomized, and neutral swallows were always first, so catheter adjustment over time may have affected values. The sample was small and standard deviations were large, so smaller effects at pH 3 and pH 5 or on other pressure measures could have been missed. Aggregating swallows per person reduced the number of independent values, making small effects harder to detect. The pH 1.8 bolus was stronger than the pH 3 and pH 5 levels described as encountered during regular food intake, so the finding may not apply to normal sour foods or reflux. Secondary significant differences were not treated as confirmatory by the authors. The study cannot identify where acid was detected, because oral, pharyngeal, and esophageal receptors were not separated.
Declared interests
Funder named: Medizinische Hochschule Hannover (MHH) (3118).
The easy way to misread this
Do not conclude that acidic reflux or sour foods cause a protective upper esophageal sphincter spasm in patients. This was a physiology study in ten healthy volunteers, and only pH 1.8 differed from neutral; pH 3 and pH 5 did not show a statistically significant difference.