Oesophageal acidification does not increase lower oesophageal sphincter pressure.
Level 5 - mechanism / opinion, no new human data
Mechanistic physiological investigation in healthy volunteers and an animal model.
PubMed 2323586 · doi:10.1136/gut.31.3.266
What was done
The authors evaluated the effect of distal oesophageal acidification on lower oesophageal sphincter (LOS) pressure in healthy human volunteers and anaesthetised cats. Acidification was induced via intraluminal injection of 0.1 N hydrochloric acid (pH 1.2). LOS pressure was measured using a sleeve device, alongside pharyngeal and oesophageal pressure monitoring via nonperfused, water-filled catheters. The physiological response to acid was compared with intraluminal saline injection in cats.
What was found
In human volunteers, distal oesophageal acidification caused no change in LOS pressure (no numerical values reported). In anaesthetised cats, acid injection caused immediate LOS relaxation followed by secondary peristalsis; when the wave reached the sphincter, LOS pressure abruptly increased by 20 to 100 mmHg and returned to baseline over 15 to 180 s. In a single instance where acid did not evoke secondary peristalsis, LOS pressure did not change. Saline injection elicited an identical motor response in cats.
Why it matters
This study challenges the belief that luminal acid directly stimulates lower oesophageal sphincter contraction, showing that pressure increases are secondary to peristalsis rather than acid-mediated sphincter stimulation.
Limits
The abstract does not report sample sizes for either human volunteers or cats, nor does it report baseline pressures or statistical variance for humans. Findings from healthy humans and anaesthetised animals may not apply to patients with gastro-oesophageal reflux disease.
Cited by
- contradicts Normal stomach acidity has a pH between 1.5 and 3.0, and elevated stomach pH causes the lower esophageal sphincter valve to fail to close properly.