Postprandial distress syndrome: stratification and management

Introduction: Functional dyspepsia (FD), defined by the Rome consensus as the presence of functional symptoms originating from the gastroduodenum, is one of the most common functional gastrointestinal disorders. FD is subdivided into postprandial distress syndrome (PDS), with meal-related symptoms such as postprandial fullness and early satiation, and epigastric pain syndrome (EPS), with meal-unrelated symptoms such as epigastric pain or burning. We used a literature search for a narrative review on the current state of knowledge regarding PDS.

Areas covered: Epidemiological studies support PDS as a separate entity and the biggest FD subgroup. The pathophysiology of PDS is heterogeneous, and disorders of gastric sensorimotor function as well as low grade duodenal inflammation have been implicated. Although prokinetic agents may provide the most pathophysiology-oriented treatment option, there is a paucity of suitable agents, and proton pump inhibitors are the traditional first-line therapy. Other options include agents that enhance gastric accommodation, such as acotiamide and 5-HT_1A agonists, neuromodulators such as mirtazapine, and traditional medicine approaches.

Expert commentary: PDS is highly prevalent, with probably heterogeneous underlying pathophysiology. Motility modifying agents and neuromodulators are the cornerstone of PDS therapy, but there is a need for high quality studies of new therapeutic approaches.     

Postprandial water intake inhibits gastric antral motility with increase of cholecystokinin in humans

Objective. The effects of postprandial water intake on the gastrointestinal tract have not been systematically investigated in humans. Material and methods. In 8 healthy volunteers, the gastric antral pressure was measured with a strain gauge transducer, while the esophageal and lower esophageal sphincter pressures were measured with an infused catheter with a Dent sleeve. The esophageal pH at 5 cm above the lower sphincter was measured with a microglass electrode. A standard test meal (560 kcal) was eaten and 500 ml water was ingested 1 h later. The plasma cholecystokinin level was assessed at 4-min intervals. As a control, the same study was done on another day with sham water intake. Results. At 4 min after water intake, there was a significant decrease in gastric antral motility and a significant increase in the plasma cholecystokinin level. Water intake also significantly increased the occurrence of gastroesophageal reflux. Conclusions. The rapid increase in cholecystokinin after water intake may be initiated by a feedback mechanism related to inflow of fatty chyme into the duodenum that inhibits gastric antral activity.     

Postprandial proximal gastric acid pocket and gastroesophageal reflux disease

An unbuffered layer of acidity that escapes neutralization by food has been demonstrated in volunteers and gastroesophageal reflux disease patients. This postprandial proximal gastric acid pocket (PPGAP) is manometrically defined by the presence of acid reading (pH < 4) in a segment of the proximal stomach between nonacid segments distally (food) and proximally (lower esophageal sphincter or distal esophagus). The PPGAP may have important clinical implications; however, it is still poorly understood. Gastric anatomy and physiology seem to be important elements for PPGAP genesis. Gastric operations and acid suppression medications may decrease distal – proximal intragastric acid reflux and help control gastroesophageal reflux.     

Gastric Electrical Stimulation Does Not Significantly Affect Canine Gastric Acid Secretion and 24-Hour Gastric pH

Gastric electrical stimulation (GES) was shown to improve symptoms in patients with gastroparesis. However, the underlying mechanisms remain unclear. This study assessed the influence of various patterns of GES on fasting and postprandial gastric acid secretion and 24-hr gastric pH. Eight healthy dogs were studied and we found that in the fasting state, low-frequency, long-pulse (6/12-cpm, 375-msec, 4-mA) GES at the proximal stomach significantly inhibited the secretion of gastric juice (P < 0.05). No such effect was observed during GES (6/12 cpm) at the distal stomach. In the postprandial period, low-frequency, long-pulse GES at both proximal and distal sites and at both frequencies did not significantly affect gastric acid secretion. High-frequency, short-pulse GES, investigated for obesity (21 Hz, 8 mA, and 250 microsec, with 2 secs on, 3 sec off), at the proximal and distal stomach did not significantly affect the 24-hr gastric pH profile. In conclusion, GES with various stimulation parameters, and at various sites, has little effect on gastric acid secretion. The clinical effects induced by GES at these parameters may not be related to their effect on gastric acid homeostasis.     

Gastroesophageal reflux and unexplained chronic respiratory disease in infants and children

Thirty-eight children, aged from a few weeks to 7 years, with severe chronic pulmonary disease and without gastrointestinal symptoms, were investigated for gastroesophageal reflux (GER), using prolonged pH probe monitoring and gastroesophageal scintiscanning. All treatments were discontinued before testing. GER was found in 24 patients (63%) (group I) and it was not observed in 14 patients (group II). All patients of group I received antireflux treatment, consisting of cisapride; in 22 of 24 patients, GER was controlled, as indicated by improvement of either pH monitoring or scintiscanning, or both. Eighteen of these 22 (82%) had remission of their pulmonary disease, and only two patients of group II (14%) had spontaneous remission of the respiratory symptoms. We concluded that GER was probably the cause of the respiratory disease in 63% of our patients, since treatment of GER was followed by disappearance of the respiratory complaints in most of them. The combination of gastroesophageal scintiscanning and pH probe study improved the diagnostic accuracy.     

高血压患者脂肪酸粘附蛋白2基因多态性与餐后甘油三酯代谢异常的关系

目的　研究原发性高血压患者 (EH)餐后甘油三酯代谢异常与脂肪酸粘附蛋白 2基因 (FABP2 )变异的关系。方法　 5 0例EH患者和 30例健康人禁食 10～ 12小时后 ,进行标准脂肪负荷试验 ,以甘油三酯 (TG) 8小时曲线下面积(TG AUC)和TG峰反应 (TGPR)作为标准脂肪负荷后TG反应水平的指标。用聚合酶链反应 (PCR)对FABP2基因5 4密码子HhaI酶切位点限性片段长度多态性进行分析。结果　 (1)EH组TG AUC ,TGPR均显著高于对照组 (TG AUC :2 0 0 2± 6 2 5比 9 6 1± 2 2 7mmol/L ,P <0 0 5 ;TGPR :4 15± 2 82比 2 0 5± 1 31mmol/L ,P <0 0 1)。 (2 )EH组FABP2基因 5 4密码子Thr型 (Thr5 4 )基因频率与正常组无显著差别 (0 2 8比 0 2 5 ,P >0 0 5 )。 (3)EH组中Thr纯合型 (Thr 5 4 /Thr 5 4 )和Thr杂合型 (Ala 5 4 /Thr5 4 )患者TG AUC、TGPR显著高于野生型 (Ala 5 4 /Ala 5 4 )者 ,纯合型患者TG AUC、TGPR显著高于杂合型 (TG AUC :2 8 2± 6 11、2 1 9± 6 16比 13 9± 6 0 7mmol/L ,P <0 0 5 ;TGPR :7 5 6± 2 6 7、4 2 0± 1 6 2比 2 34± 1 4 7mmol/L ,P <0 0 5 )。结论　高血压病患者存在餐后TG代谢障碍和消除延迟 ,FABP2基因 5 4密码子Thr改变是餐后甘油三酯代谢异常的影响因素之一     

Diminished Retention of Food in the Proximal Stomach Correlates with Increased Acidic Reflux in Patients with Gastroesophageal Reflux Disease and Dyspeptic Symptoms

This work aimed at evaluating the intragastric distribution of food in patients with GERD and dyspepsia and its relationship to acidic reflux episodes. Gastric emptying and food retention in the proximal stomach were evaluated by scintigraphy in 12 healthy subjects and 19 patients with GERD and dyspepsia after a liquid test meal. Patients also underwent 24-hr esophageal pH monitoring, which included a 2-hr postprandial period following a similar test meal. Total gastric emptying was similar in patients and controls, whereas proximal gastric retention (AUCprox/AUCtot) was significantly decreased in patients (mean +/- SD: 0.48 +/- 0.07 vs. 0.56 +/- 0.06; P = 0.02). Within the GERD-dyspepsia group, a significant negative correlation was found between proximal gastric retention and the number of acidic reflux episodes. We concluded that abnormally decreased retention of gastric contents in the proximal stomach after a liquid meal may contribute to the pathogenesis of acidic reflux episodes in patients with GERD and dyspepsia.     

Postprandial Plasma Glucose Response and Gastrointestinal Symptom Severity in Patients With Diabetic Gastroparesis

Background:Gastroparesis is a well-known diabetic complication. The pathogenesis is not fully understood. However, it is important to early diagnose these patients.Method:This study evaluated the plasma glucose response after a test meal, and gastrointestinal (GI) symptom severity in patients with clinical suspicion of diabetic gastroparesis, and assessed its usefulness to predict gastroparesis. In all, 83 subjects with insulin-treated diabetes mellitus (DM) type 1 and 2 were included; 53 subjects had gastroparesis and 30 had normal gastric emptying determined by gastric scintigraphy. GI symptom severity during the preceding 2 weeks was evaluated with a validated questionnaire. The test meal consisted of 100 g meat, 40 g pasta, 150 g carrot, and 5 g oil. The subjects ingested the meal under fasting conditions, and plasma glucose was followed during 180 minutes.Results:Patients with gastroparesis demonstrated a blunted plasma glucose response after a test meal versus patients with normal gastric emptying (P < .005), reflected by lower maximum increase in plasma glucose response and incremental area under the curve of the plasma glucose, but a similar time to the maximum plasma glucose level. All GI symptoms were more severe in patients with gastroparesis. GI symptom severity had the best discriminative value to identify patients with gastroparesis with an area under the receiver operating curve of 0.83 (optimal cutoff: sensitivity 87%, specificity 80%).Conclusions:Patients with diabetic gastroparesis have a blunted postprandial plasma glucose response. Combining this information with the presence of GI symptoms can help clinicians identify diabetic patients with gastroparesis.     

Gastric acid secretion and gastrin release in the baboon

Significant species differences have been demonstrated in gastric physiology, a factor that limits extrapolation of animal data to man. Primate physiology is thought to be similar to that of man; however, gastric function has not been adequately documented in the primate. In the present study six baboons (body weight 25.5±1.8 kg) were trained to sit in a chair and gastric acid secretion and gastrin release was studied in conscious animals. Mean basal acid secretion was 1.3±0.1 mmol (H⁺)/hr. Maximum output after pentagastrin (12 g/kg/hr) was 9.5±0.9 mmol (H⁺)/hr and 11.0±0.4 mmol (H⁺)/hr after histamine (40 g/kg/hr). A statistically significant (by cosinor analysis) circadian rhythm was demonstrated for intragastric pH over 24 hr in fasted baboons (P<0.001). Mean basal serum gastrin level was 37.7±8.3 pg/ml. The integrated gastrin response after administration of a protein rich meal was 2.52±0.07 ng×min/ml and this increased to 5.17±0.18 ng×min/ml (P<0.05) following simultaneous administration of a meal with atropine (0.2 mg/kg) (P<0.05). Our results suggest that there is significant basal and stimulated acid secretion in the baboon; the amount of acid secreted is similar to that reported in man. Gastric pH demonstrated a circadian rhythm. Postprandial gastrin release was significantly enhanced by cotreatment with atropine. As the present findings are similar to those previously reported in man, the baboon may be a useful model for further studies in gastric physiology and experimental peptic ulceration.     

经内镜胃液pH值侧定诊断慢性萎缩性胃炎402例的价值

本文报告402例慢性胃炎患者经内镜胃液pH值测定结果,探讨胃液pH值对慢性萎缩性胃炎(CAG)的诊断价值。结果显示:CAG胃液pH值显著高于慢性浅表性胃炎(CSG,P<0.01),在CAG中随着萎缩程度加重,其胃液pH值逐渐增高(P均<0.01),CAG伴肠上皮化生或不典型增生者,其胃液pH值高于单纯CAG患者。结论:胃液pH值测定较内镜直视观察诊断符合率为高,其敏感性、特异性、阴性预测值强,故胃液pH值测定对提高CAG的诊断具有参考价值。     

Indications for 24-hour gastric pH monitoring with single and multiple probes in clinical research and practice

The methodology of prolonged gastric pH monitoring has not yet been standardized with regard to the number and position of pH probes. Twenty-seven healthy volunteers and 11 patients affected by nonulcer dyspepsia have been submitted to 24-hr ambulatory simultaneous pH monitoring of the distal esophagus, fundus, and antrum. Fundic and antral pH profiles have been compared and causes of pH variations (pH>4) identified. Both in healthy volunteers and dyspeptic patients, percentile curves of fundic and antral pH were statistically different in more than one of the daily periods considered (24-hr, postprandial, interdigestive, nocturnal). Percent time of duodenogastric reflux is significantly higher in the antrum than in the fundus in both groups. Modalities of gastric alkalinization secondary to food or duodenogastric reflux were different for the fundus and for the antrum both in healthy and dyspeptic subjects and between the two groups. These differences suggest that single and multiple pH monitoring of the stomach have different indications, and the position of the probes should vary according to the purpose of the test.     

Gastroduodenal mucosal surface and luminal pH in gastric ulcer

Gastroduodenal mucosal surface pH was measuredin situ by electrode in endoscopically normal and gastric ulcer patients. With the exception of the antrum, mucosal surface pH in the ulcer group (GU) resembled that of the endoscopically normal group. In contrast, the antral mucosal surface pH of the GU group of 7.06±0.11 (22) was significantly (P<0.001) higher than that of 5.46±0.36 (34) for the endoscopically normal group. This difference was also evident when comparison was restricted to subjects in both groups having a fundal luminal fluid pH of less than 3. When the fundal luminal pH was below pH 3, antral mucosal surface pH was 4.79±0.41 (24) in endoscopically normal subjects and significantly less (P<0.001) than the value of 6.98±0.18 (12) for gastric ulcer patients. Mucosal surface alkalinity of the GU antrum may be a response to damage but seems inappropriate in view of the likelihood of acid dependent inhibition of gastric acid secretion.     

The pH Measurement of Fasting Gastric Juice in Acute Gastric Mucosal Lesions

Abstract: Fasting gastric juice acidity was assessed to elucidate its role in the cause of acute gastric mucosal lesions (AGML). Gastric juice was aspirated through an auxiliary endoscopic channel during routine endoscopic examinations, and its pH was measured with a glass electrode PH meter. The pH of 100 cases with AGML (acute hemorrhagic erosions (AHE), acute gastric ulcer and acute hemorrhagic gastritis), and 586 cases with other ulcerative or inflammatory lesions were compared with the gastric juice pH in 1775 endoscopically normal subjects. The pH value was classgied into four acid groups: Hyperacidity (pH < 1.4), Normoacidity (1).5 < pH < 2.0), Hypoacidity (2).1 < pH <4.0) and Anacidity (4). 1 < pH). In cases with AHE, a signifcant hyperacidity was recognized both in the periods preceding and just after the onset. This hyperacidity was followed by signgicant anacidity, and thereafter a return to normoacidity. These pH changes coincided well with endoscopic appearances; preceding stage-hypernormacidity, black-slough stage—hyperacidity, white-slough stage-anacidity and scarring stage-;normoacidity. These results suggest that an elevation of gastric acidity etiologically relates with the formation of AGML, especially Shin.     

The Origin of Nocturnal Intragastric pH Rises in Healthy Subjects

Background: Duodenogastric reflux (DGR) can produce transient increases in gastric luminal pH. It has been proposed that intragastric pH-metry is a reliable method for the detection of DGR. Our aim was to test the hypothesis that nocturnal increases in antral pH are due solely to DGR. Methods: Gastric pH was monitored overnight using two glass pH electrodes, one in the antrum adjacent to the tip of a nasogastric tube and one in the corpus. Scheduled antral aspirations were performed hourly to determine base-line concentrations of total bile acids (TBA; a marker of DGR) and thiocyanate (SCN; a marker of swallowed saliva). Additional, triggered aspirations were performed if antral pH exceeded 3.0 for 1 min or more (PHAP; period of high antral pH). TBA and SCN were considered to be increased if they exceeded the 90th percentile of values determined in scheduled aspirates (TBA, 0.88 mM; SCN, 0.67 mM). Results: In 28 of the 62 samples whose aspiration was triggered by a PHAP the pH was less than 3.0, and the sample was not considered to be representative. In the remaining 34 samples the antral luminal pH and the sample pH were concordant; TBA alone was increased in 6 samples, SCN alone was increased in 6 samples, and TBA and SCN were both increased in another 3 samples. Thus, DGR and swallowed saliva alone or in combination accounted for only 15 (45%) of the PHAP in which adequate gastric samples were obtained. Conclusion: Samples of gastric antral contents often do not reflect accurately the acidity of gastric fluid in contact with a luminal antral pH electrode. Nocturnal increases in antral pH, detected by a luminal electrode, are frequently due to mechanisms other than duodenogastric reflux or swallowed saliva. Thus, antral pH-metry is not suitable for monitoring the occurrence of duodenogastric reflux.     

胃食管反流病食管测压与24小时pH监测的相关性研究

目的：对５２例有胃食管反流症状的患者进行食管测压及２４小时ｐＨ监测，运用统计学方法分析测压和ｐＨ结果，研究其相关性。方法：应用多导胃肠功能测定仪及便携式ｐＨ监测记录仪，对５２例有胃食管反流症状的患者进行食管测压及２４小时ｐＨ监测。结果：应用多元回归分析发现，ｐＨ的百分比和腹段下食管括约肌（ＬＥＳ）的长度、ＬＥＳ静息压及远端食管的蠕动压明显相关。依据测压及ｐＨ结果，使用ｔ检验方法，结果提示食管蠕动压不仅与ｐＨ＜４的百分化相关，也与酸反流大于５分钟的时间、最长反流时间有关（Ｐ＜００１）。结论：腹段ＬＥＳ的长度及食管下段的蠕动收缩是重要的抗反流屏障。食管酸暴露时间延长减弱食管体部酸清除能力     

Oesophageal pH monitoring in infants: elimination of gastric buffering does not modify reflux index

BACKGROUND: Oesophageal pH monitoring is considered to be the gold standard investigation in the diagnosis of gastro-oesophageal reflux disease. Results of pH monitoring in regurgitating infants, however, may be within normal ranges. Therefore it was hypothesized that prolonged buffering of gastric acidity caused by milk-feeding may falsely normalize the pH data. Therefore, it may be relevant to omit the periods of gastric acid buffering in the analysis of the oesophageal pH monitoring data. METHODS: Combined gastric and oesophageal pH monitoring (Digitrapper Mark III, two-channel antimony electrode, Synectics) was performed in 90 consecutive infants, 0.5-10 months old, who were referred to the unit by outdoor paediatricians for pH measurement. The data were analysed in three different ways. The reflux index (RI), or the percentage time that the pH in the oesophagus was < 4.0, was calculated in three different ways: (i) the total duration of the investigation; (ii) excluding 90-min postprandial periods, starting from the beginning of a feeding; and (iii) excluding all periods with a gastric pH > 4.0, which are the periods of gastric buffering with a theoretical impossibility of recording an oesophageal pH < 4.0. RESULTS: The mean duration of the pHmetries was 19.20+/-2.01h (A; mean +/- 1 SD), with a RI of 5.38+/-5.39% (B; median 3.45%). If the 90-min postprandial periods were not considered, the mean duration decreased to 12.21+/-2.41h (C; P(A vs C) < 0.001), with an oesophageal RI of 6.82+/-6.57% (D; median: 4.65; P(B vs D) = NS; r (B vs D) = 0.97). If all periods with a gastric pH > 4.0 were elminated, the duration available for analysis of the data with a gastric pH < 4.0 was 12.53+/-4.00 h (E; P(A vs E) < 0.001; P(C vs E) = NS), with an oesophageal RI of 7.06+/-7.52% (F; median: 4.50; P(B vs D vs F) = NS; r(B vs F), (D vs F) = 0.96). CONCLUSION: Overall the data do not support a benefit from including periods of gastric buffering in the routine analysis of oesophageal pH monitoring data. Therefore standard oesophageal pH monitoring should be with a single electrode and should not include periods of gastric buffering.     

正常人和胃食管反流病人的昼夜食管pH和动力变化

目的:为探讨正常人和胃食管反流病(gastroesophageal reflux disease,GERD)病人昼夜食管运动规律以及食管运动与酸反流的关系。方法:45例GERD病人和10名正常人均接受食管测压和动态食管pH及压力同步监测。结果:(1)下食管括约肌压、远端食管蠕动压及有效食管蠕动百分比在酸反流DeMeester高计分组明显低于低计分组(P<0.05),在反流性食管炎组也明显低于非反流性食管炎组(P<0.05)。(2)有GERD症状或食管炎的卧位有效蠕动百分比明显低于立位(P<0.05)。反流性食管炎组80％有夜间或伴有夜间反流,而不伴反流性食管炎的GERD无1例出现夜间反流。结论:昼夜食管pH和压力动态监测有利于进一步探讨GERD的运动病理,除LES功能外,食管清除功能在GERD发病中起重要作用。     

Gastroesophageal and laryngopharyngeal reflux detected by 24-hour combined impedance and pH monitoring in healthy Chinese volunteers

OBJECTIVE: To define the normative data of gastroesophageal reflux (GER) and laryngopharyngeal reflux (LPR) in healthy Chinese volunteers. METHODS: Healthy volunteers without gastrointestinal and throat disease and symptoms were enrolled and underwent 24‐hour impedance‐pH monitoring. RESULTS: A total of 37 healthy volunteers completed all the tests (female 54.1%; age 38.0 ± 15.2 years). Of 1862 GER, 49.6% were mixed, 40.9% were liquid and 9.5% were gas. More than half (54.9%) were acid. The median and 95th percentile numbers of GER were 52 and 71, respectively. The number of LPR was eight, of which two were mixed and the others were liquid. Only one episode of reflux was classified as acid LPR. The median and 95th percentile numbers of LPR were 0 and 2, respectively. More liquid reflux were associated with LPR (P = 0.02). Age had no influence on GER and LPR reflux profiles. CONCLUSIONS: Few LPR occurred in healthy Chinese volunteers and they were rarely acid when they reached the larynx. LPR was mostly associated with liquid reflux.     

Antimony and glass pH electrodes can be used interchangeably in 24-hour studies of gastric acidity

Antimony and glass pH electrodes show almost identical experimental errors in continuously measuring buffer solutions at constant temperature over 24 hr. These errors are lower than the nominal quantization error of the instruments and are not properly described by the 24- hr drift determination. The addition of food particles to the solutions can induce severe reading artifacts. The longer response time reported in vitroof antimony electrodes when moving from pH 1 to pH 7 (3.4 sec vs 0.8 sec with glass electrodes) is irrelevant during in vivopH-metry studies, because we found that the greatest absolute difference between raw fast acquired (4–6 sec) consecutive pH readings of two commonly used devices was 0.7 pH units in circadian profiles obtained from 413 subjects with various clinical conditions. In our in vivo studies, gastric acidity was monitored continuously with two side-by-side minielectrodes, which were variously combined (antimony-glass, A-G; antimony-antimony A1–A2; glass-glass, G1–G2) and applied on groups of 27 subjects matched for clinical condition. The 24-hr pH means and the 24-hr [H⁺] means calculated from the acidity profiles obtained with the three electrode combinations, lie on the identity line in each group. Using the Bland-Altman technique for assessing measurement agreement, the differences between the 24- hr pH means and the 24-hr [H⁺] means obtained with the three combined systems are similar (P=.903 and P=0.824, respectively) and their 95% confidence limits are comprised within the range (±) of the reading error of the measuring systems (namely, ±0.3 pH units and ±12 mmolliter in terms of [H⁺]). These data show that the 24-hr acidity indexes calculated from gastric pH recordings performed with two closely adjacent antimony and glass electrodes are similar, irrespective of their possible combinations. It can be concluded that antimony and glass electrodes provide equivalent results in vivo and can be used interchangeably in the clinical setting.     

A New Method for Measurement of the Electrical Potential Difference across the Stomach Wall: Clinical Evaluation of the Gastric Mucosal Integrity

PD, the electrical potential difference across the gastric mucosa, is a variable used frequently in experimental studies. Existing methods for PD measurements are, however, unstable, and variations in the pH of the gastric juice causes liquid junction potentials between gastric juice and the PD measuring probe. A new PD measuring system has been developed with high stability, easy handling, and correction for the liquid junction potcntials. PD was measured between a stomach microelectrode and an intravenous reference electrode connected to a millivoltmeter. pH was measured by an intragastric microelectrode. The liquid junction potential was calculated by using the pH measured in the gastric juice and the Henderson equation and was then subtracted from the measured PD to provide a better approximation of the PD across the mucosa. The liquid junction potential calculated as stated above correlated with the liquid junction potential calculated from precise ion determinations made in gastric juice samples (y = x; r = 0.92; p < 0.05). The reliability of the PD measuring system was tested in vitro and in vivo and was satisfactory. In conclusion, a new. reliable, and easily applied method for gastric PD measurements corrected for the liquid junction potential between gastric juice and the PD measuring probe has been developed.