A Pilot Study on Duodenal Acid Exposure and Its Relationship to Symptoms in Functional Dyspepsia with Prominent Nausea

Abstract

BACKGROUND: Duodenal hypersensitivity to acid and decreased duodenal clearance of exogenous acid have been reported in functional dyspepsia (FD). However, the relevance of these abnormalities to spontaneous duodenal acid exposure and dyspeptic symptoms in FD is unknown. AIMS:To determine spontaneous duodenal acid exposure and its relationship with symptoms, duodenal sensitivity to acid, and the effects of a 5-HT 3 receptor antagonist on duodenal responses to acid in FD. METHODS:Eleven FD patients with prominent nausea and 11 healthy controls underwent 24-h ambulatory duodenal pH monitoring with assessment of dyspeptic symptoms. On the next day, duodenal bolus infusions of 5 ml of acid and normal saline were given in a randomized double-blind manner and repeated after ondansetron or a placebo. RESULTS:Nighttime duodenal acid exposure was similar, but FD patients had lower duodenal pH and higher duodenal % time (pH < 4) than controls during the daytime and in the second postprandial 2 h (p < 0.05). Seven patients (64%) with duodenal acid exposure above the normal range had higher severity scores for several dyspeptic symptoms including nausea. However, the symptom severity was poorly or weakly correlated to duodenal pH, and brief duodenal acid infusion did not affect any symptoms. Duodenal responses to exogenous acid were unaffected by 5-HT 3 receptor antagonism.CONCLUSIONS: Spontaneous duodenal acid exposure is increased in a subset of FD patients with prominent nausea, and this is associated with more severe dyspeptic symptoms. However, a direct relationship between duodenal acid exposure and symptom severity is lacking.

Effect of a proton pump inhibitor on postprandial gastric volume, emptying and symptoms in healthy human subjects: a pilot study

“…23,24 In fact, several groups have reported increased sensitivity of the duodenum to infused acid. 25,26 However, the precise mechanism for the acid-induced postprandial symptoms is unclear. Tack and colleagues demonstrated that high concentrations of acid were associated with significant changes in motor function such as increased fundic tone or induction of migrating motor complex (MMC)-like activity that could conceivably alter thresholds for sensation to distensions of the fundus.…”

Functional dyspepsia

“…Functional dyspepsia symptoms after duodenal acid infusion 74 could result from sensitization of transient receptor potential cation channel subfamily V member 1 (TRPV1) or decreased acid clearance from Box 1 | Rome IV symptom criteria for functional dyspepsia and its subtypes*…”

Pathophysiology and Treatment of Functional Dyspepsia

“…Furthermore, recent studies have suggested a role for increased duodenal acid exposure or hypersensitivity to duodenal acid in the pathogenesis of functional dyspepsia. 53,54 In patients with duodenal acid hypersensitivity, a tendency toward a decrease of duodenal acid hypersensitivity was observed after 2 weeks of proton pump inhibitor treatment. However, potential benefits of acid-suppressive treatment of functional dyspepsia patients with increased duodenal acid exposure remain to be defined.…”

“…[47][48][49][50] Other Mechanisms A number of other pathophysiologic mechanisms have been implicated in the pathophysiology of functional dyspepsia, based on limited numbers of studies, generally in small groups of patients. These include duodenal hypersensitivity to lipids, 51,52 increased duodenal acid exposure due to impaired duodenal clearance, 53,54 lack of postprandial suppression of phasic contractility of the proximal stomach, 55 and abnormalities of gastric electrical rhythm. 56,57 …”