Comparison of gastric body and antral pH: a 24 hour ambulatory study in healthy volunteers.

Simultaneous ambulatory records of gastric antral and body pH were made over 24 hours in nine healthy volunteers by means of endoscopically positioned and anchored glass electrodes. Intragastric pH was temporarily raised after the endoscopy with the median pH value 30 minutes after the procedure being 3.9 (range 1.5-7.0) for the antrum and 4.1 (range 1.5-7.0) for the body. Daytime pH (median pH value between 12 00 h and 23 00 h) was lower in the antrum (median = 1.9, range 1.6-2.6) than in the body (median = 2.7, range 1.8-4.5) (p less than 0.05) and this was because of the rise in pH on eating being less marked in the antrum than in the body. The median peak pH recorded during the evening meal was only 4.1 (range 2.4-6.2) in the antrum compared with 6.3 (range 4.4-6.7) in the body (p less than 0.01). Preprandial pH (median value over the hour prior to the evening meal) was similar in the antrum (median = 1.9, range 1.2-2.5) and body (median = 1.9, range 1.3-2.8). Night-time pH (median pH value between 23 00 h and 05 00 h) in six subjects remained low and was similar in the antrum (median = 1.4, range 1.2-1.7) and body (median = 1.3, range 1.1-1.7). In two subjects, however, there were episodes of raised night-time pH which were more marked in the antrum than in the body. Antral biopsies showed gastritis in four of the nine normal volunteers, which in three was associated with the presence of campylobacter-like organisms. This study shows the significant regional variations in day and night-time intragastric pH.     

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.     

50名正常中国成人食管24小时pH监测结果分析

为获得我国正常成人食管酸暴露的正常值范围，对５ｏ名健康成人进行２４小时ｐＨ监测。结果显示：５ｏ名正常成人中平均９８．６％的时间食管ｐＨ＞４，故以ｐＨ４作为酸反流的阈值。观察６项食管酸暴露的指标，得出９５％的正常值范围：ｐＨ＜４的总时间百分率为３．４％；ｐＨ＜４的立位总时间百分率为４，３％；ｐＨ＜４的卧位总时间百分率为４．３％；反流持续≥５分钟的次数≥２次；最长反流持续时间１６分钟；ｐＨ＜４的反流次数为６ｏ次；总计分１２．７分。门诊与住院检查结果比较，二者差异无显著性（ｐ＞０．０５）。本结果与国外资料不同，可能与种族、地区差异、人群生活习惯、饮食结构的不同或ＬＥＳ功能等有关。     

24-hour oesophageal two-level pH monitoring in healthy children and adolescents

Two-level pH recording in the oesophagus was performed for 24 h in 28 healthy schoolchildren between 9.3 and 17.3 years of age, to obtain reference values for reflux studies. The pH probes were placed 5 and 15 cm above the lower oesophageal sphincter by means of the manometric technique. A standardized acid-free diet was given on the day of recording. A drop in pH to 4.0 or below was regarded as reflux. The normal upper limit of total reflux time was 1.0% at the lower oesophageal level. Mean reflux time was about three times shorter at the upper level than at the lower, which indicates the importance of exact positioning of the pH probe.     

正常人24小时胃电图检测分析

目的研究正常人２４小时胃电变化规律。方法用动态胃电图检测仪检测３０例正常人２４小时胃电图。结果平均正常胃电频率占６７．６５％（６４．５％～９４．２％），胃动过缓占１４．１５％（１．９％－２１．２％），胃动过速占８．９６％（２．０％～２０．０％）。餐后胃电主要功率较餐前明显增加（Ｐ＝０．０１４），餐后餐前主功率比值为３．１５±２．７８。三餐对胃电频率影响相似，餐后１５分钟胃电频率稍降低（Ｐ＜０．０１），此后胃电频率恢复至餐前水平。将２４小时胃电图资料，按每６小时一段，分为４段，各段时间内胃电图检测结果相似（Ｐ＞０．０５）。结论动态２４小时胃电图监测是研究长时间胃电节律变化的有效方法。     

Physical and pH properties of gastroesophagopharyngeal refluxate: a 24-hour simultaneous ambulatory impedance and pH monitoring study

OBJECTIVES: Frequency occurrence of nonacidic and nonliquid reflux events in the pharynx has not been systematically studied. The aim of the present study was to characterize the physical (liquid, gas, and mixed gas/liquid) and pH properties of the gastroesophagopharyngeal refluxate. METHODS: We performed a total of 31 24-h simultaneous ambulatory pharyngoesophageal impedance and pH recordings in 11 GERD patients, 10 patients with reflux-attributed laryngitis, and 10 healthy controls. RESULTS: On average, the total number of reflux events (all kinds) in the pharynx was less than half of that in the proximal esophagus (18 +/- 4 vs 50 +/- 4, p < 0.01). Most of the pharyngeal reflux events were gas events and were observed in all three studied groups. Prevalence of these gas reflux events ranged between 0 and 74. The number of gas reflux events accompanied by a minor pH drop in laryngitis patients (1 (0-36)) was significantly higher than those in GERD and controls (0 (0-2) and 0 (0-1), respectively, p < 0.05). There was no significant difference in the number of nonacidic gas reflux events among the three groups (GERD: 10 (2-57), laryngitis: 11.5 (0-51), controls: 10.5 (0-27)). Impedance recording identified a total number of 566 events in the pharynx. Of these, a total of 563 events were compatible with gas reflux events, 101 events were accompanied by minor drops in intrapharyngeal pH, whereas 460 events were not accompanied by any pharyngeal pH change. CONCLUSIONS: Concurrent impedance and pH recordings detect significantly more events qualifying as reflux in the pharynx than pH recordings alone. A substantial majority of these events are gaseous refluxes both with and without minor pH drops. Gas reflux events with weak acidity appear to be more common among patients with reflux-attributed laryngeal lesions compared to GERD patients and controls.     

24-H Pharyngeal pH Monitoring in Healthy Volunteers: A Normative Study

Background: Gastropharyngeal reflux has been associated with disorders of the upper and lower airways. It may be shown by pharyngeal pH-metry, but reports on normality in healthy volunteers are scarce. No definite consensus has been reached considering the upper limit of normality (ULN). The aim of the present study was therefore to quantify the occurrence of pharyngeal acid exposure (pH &lt; 4) in healthy volunteers and, further, to examine its relation to acid exposure of the oesophagus and oesophageal motility and its occurrence in relation to age, sex, and body position. Methods: Forty healthy volunteers underwent ambulatory 24-h pH-metry, using antimony electrodes positioned 2 cm above the upper oesophageal sphincter and 5 cm above the lower oesophageal sphincter on the basis of manometry. Technical artefacts were excluded before calculation of all results. Results: Gastropharyngeal reflux occurred in most healthy volunteers without any significant relation to age, sex, or body weight. Pharyngeal acid reflux occurred mainly in the upright position. The ULN for pharyngeal acid exposure time was assessed to 0.9% (0.2% after exclusion of mealtimes). The ULN for the number of acid events in the pharynx was 18 (6.1). The corresponding ULNs for the oesophagus were 7% and 84. Conclusion: Gastropharyngeal reflux may be effectively monitored by ambulatory pH-metry. The present study provides reference limits, a prerequisite for evaluating the pathophysiologic importance of the phenomenon.     

Twenty-four hour ambulatory simultaneous impedance and pH monitoring: a multicenter report of normal values from 60 healthy volunteers

OBJECTIVES: Impedance monitoring is a new diagnostic method for gastroesophageal reflux disease (GERD) where multiple impedance electrode pairs are placed on a standard pH catheter. It detects reflux of a liquid and/or gas bolus into the esophagus, as well as its distribution, composition, and clearing. The aim of this collaborative study is to define normal values for 24-h ambulatory simultaneous impedance and pH monitoring (24-h Imp-pH), and compare bolus parameters by impedance monitoring to changes in [H(+)] measured by pH monitoring. METHODS: Sixty normal volunteers without GER symptoms underwent 24-h Imp-pH with impedance measured at six sites (centered at 3, 5, 7, 9, 15, and 17 cm above lower esophageal sphincter) and pH 5 cm above the LES. Reflux detected by impedance was characterized by the pH probe as either acid, weakly acidic, nonacid, or superimposed acid reflux. Proximal reflux was defined as reflux that reached the impedance site 15 cm above the LES. RESULTS: Reflux frequency was common upright (median-27, 25th and 75th quartile-16, 42), but rare recumbent (median-1; 0, 4). A median of 34% (14%, 49%) of upright reflux reached the proximal esophagus. There was a similar number of mixed composition (liquid + gas; 49%) and liquid-only reflux (51%). Acid reflux was two-fold more common than weakly acidic reflux (p < 0.001). Superimposed acid reflux and nonacid reflux were rare. Acid neutralization to pH 4 took twice as long as volume clearance measured by impedance. CONCLUSIONS: Combining impedance and pH monitoring improves the detection and characterization of GER. This study characterizes the frequency, duration, and extent of reflux in health and provides normal values for 24-h Imp-pH for future comparison with GERD patients.     

Pharyngeal reflux episodes at pH 5 in healthy volunteers

OBJECTIVE: The clinically used cut-off limit in reflux disease is pH 4. Yet, earlier studies have shown a poor correlation between pharyngeal reflux episodes and symptoms or laryngeal findings, and treatment results have been suboptimal. Moreover, recent data suggest that pepsin is still active at pH 5. The aim of this study was to evaluate the occurrence of pharyngeal pH 5 reflux episodes in healthy controls and to correlate these to the pH monitoring results with a cut-off limit of pH 4. MATERIAL AND METHODS: The results of double-probe 24-h pH monitoring from 35 healthy controls were reanalysed concerning the occurrence of pH decreases to pH 5. RESULTS: Pharyngeal pH 5 reflux episodes occurred in 32 healthy controls (91%). The median number of pharyngeal reflux episodes at pH 5 was 4.0. The vast majority of these reflux episodes (92%) occurred in the upright position, especially in the postprandial period. The median time pH < 5 in the pharynx was 0.1% while the upper limit of normality was 1.5%. Pharyngeal pH 5 reflux episodes were 5 times more common than pH 4 reflux episodes. There was a significant positive correlation between hypopharyngeal and oesophageal acid exposure time at both pH 4 and 5 (p<0.01). CONCLUSIONS: Pharyngeal pH 5 reflux episodes are present in most healthy adults, mainly in upright position and in the postprandial period. The importance of these episodes for the occurrence of laryngeal symptoms and signs and for treatment response needs to be prospectively assessed.     

Ambulatory 24-hour esophageal pH monitoring

If 24-hour esophageal pH monitoring is to be a useful diagnostic tool, it must reliably discriminate gastroesophageal reflux patients despite daily variations in distal esophageal acid exposure. To address this issue, we studied 53 subjects (14 healthy normals, 14 esophagitis patients, and 25 patients with atypical symptoms) with two ambulatory pH tests performed within 10 days of each other. Intrasubject reproducibility of 12 pH parameters to discriminate the presence of abnormal acid reflux was determined. As a group, the parameters of percent time with pH<4 (total, upright, recumbent) were most reproducible (80%). Therefore, a subject was defined as having gastroesophageal reflux disease if at least one of these three values were abnormal. Intrasubject reproducibility for the diagnosis of reflux disease was 89% for the entire sample. Among subsets, the reproducibility was 93% for the normals and esophagitis patients and 84% for the atypical symptom patients. Total percent time with pH<4 was the single most discriminate pH parameter (85%) and nearly equaled that of the three combined parameters (89%). The intrasubject variability of this parameter was determined by the mean ±2sd of the relative differences between the two test results for all 53 subjects. Total percent time with pH<4 may vary between tests by a factor of 3.2-fold or less (218% higher to 69% lower). We conclude: (1) ambulatory 24-hr esophageal monitoring is a reproducible test for the diagnosis of gastroesophageal reflux disease; and (2) the large intrastudy variability in 24-hr total acid exposure may limit this test's usefulness as a measurement of therapeutic improvement.Supported, in part, by Public Health Services Grant AM 34200-01A1 from NIADDIK.     

三种奥美拉唑胶囊健康人的生物利用度及其对胃内24小时pH值的影响

目的 比较３种奥美拉唑产品（洛赛克、奥克、奥美拉唑）４０ｍｇ在健康人的生物利用度及对胃内２４ＰＨ值的影响。方法 交叉试验设计：１８例健康志原者（男１２例,女６例）被随机分成３组,每组交叉服用洛塞克、奥克、奥美拉唑胶囊１次４０ｍｇ,交叉间隔时间７天。结果 药代动力学研究结果表明相对于奥克胶囊与奥美拉唑胶囊,洛赛克胶囊有吸收速度快、血药浓度高与持续时间长及生物利用度高的优点。胃内２４Ｐ俞 不同胶囊服用     

Performance of a continuous glucose monitoring system during controlled hypoglycaemia in healthy volunteers

It has been suggested that the continuous glucose monitoring system may be a useful tool for detecting unrecognised hypoglycaemia, especially at times when finger prick testing is difficult or impossible (e.g., at night). Studies suggest that subcutaneous glucose levels closely mimic blood glucose levels with a lag time of only a few minutes. However, no studies have been published to show how well the sensor performs during sustained or in recovery from hypoglycaemia. This study involved using a hyperinsulinaemic glucose clamp (60 mU/m2) in nine healthy volunteers. Each subject had two sensors inserted the day before the study. Blood glucose levels were maintained at euglycaemia for the first 60 min, then decreased to 45 mg/dL (2.5 mmol/L) for 60 min, and finally restored to euglycaemia. Blood glucose measurements were compared with interstitial values recorded by the sensor. Sensor profiles showed acceptable agreement with blood glucose levels at each of the three plateaus with a correlation coefficient of 0.79, slope of 0.85, and mean absolute error of 7%. The sensor drop closely matched the drop in blood glucose, but the recovery from hypoglycaemia was delayed by an average of 26 min. Continuous glucose sensing provides a useful means of detecting unrecognised hypoglycaemia in type 1 diabetes, although the duration of hypoglycaemia may be overestimated.     

含餐8 h食管pH监测与常规24 h pH监测对胃食管反流病的诊断价值比较

目的探讨含餐8h食管pH监测对胃食管反流病(GERD)的诊断意义,并以常规24hpH监测为标准验证其灵敏度及特异度。方法对2003年3月至2006年9月北京大学人民医院消化科221例患者进行食管测压和pH监测。首先由系统计算24h DeMeester积分,≥14.72分诊断为胃食管反流病。入选患者晚餐开始共计8h的监测数据,同样计算DeMeester积分,相同的标准诊断胃食管反流病。比较两种方法的一致性及积分的相关性。结果221例患者经常规24hpH监测诊断胃食管反流病124例,正常97例,含餐8hpH监测方法诊断胃食管反流病120例,正常101例。含餐8h的灵敏度为93.5%,特异度95.9%,经Kappa及Mc-nemar检验2种方法具有良好的一致性,部分结果的差异不具有显著性。2种检测方式DeMeester积分的相关系数为0.929。结论含餐8小时监测法和24hpH监测法具有良好的一致性,有望用于GERD特别是内镜阴性GERD的诊断。     

41例老年人胃食管反流病24小时食管pH测定结果分析

目的探讨老年人食管酸暴露频率强度与胃食管反流病的关系。方法应用食管ｐＨ测定方法，对４１例有胃食管反流症状者和１５例健康老年人进行２４小时食管ｐＨ监测。结果健康老年人ｐＨ＜４的总时间百分比＜３３％，立位ｐＨ＜４时间百分比＜５５％，反流＞５分钟次数＜２次，ｐＨ＜４反流次数＜６５次，但卧位ｐＨ＜４时间百分比为＜１４％。４１例有胃食管反流症状者中，３８例酸反流得分＞１４５，包括１５例内镜下无食管炎征象者，阳性率达９２５％。根据内镜下有无食管炎，比较食管粘膜损伤组与无食管粘膜损伤组之间各项ｐＨ指标的异同。可见ｐＨ＜４的总时间百分比、卧位ｐＨ＜４时间百分比和持续反流＞５分钟次数有明显不同。结论老年人食管粘膜暴露频率时间与胃食管反流病的严重程度有关。     

24-hour intragastric pH: continuous monitoring or nasogastric aspiration?

Hourly gastric aspiration has commonly been used to assess the efficacy of antisecretory compounds. We have compared continuous ambulatory 24-hour pH monitoring using a radiotelemetry capsule with standard nasogastric aspiration. Eight studies were performed on four male duodenal ulcer patients in remission receiving either placebo or an antisecretory agent. A significant correlation was found between capsule and aspirate pH measurements (r = 0.88, p less than 0.01). Radiotelemetry capsule measurements clearly showed the onset of action of an antisecretory drug, and the buffering effect of food. Radiotelemetric pH monitoring is shown to be as good as gastric sampling in the measurement of 24-hour intragastric acidity, allows continuous measurement of pH during normal activity and can accurately assess the effect of drugs on gastric acidity.     

Insulin-induced hypoglycemia: 24-H variation

Summary The hypoglycemic effect of i.v. insulin injected at 4 different times of day was studied in normal volunteers. It was found that the glucose fall induced by this treatment was quantitatively different, with the maximum effect observed at 18⁰⁰ and 24⁰⁰. The circadian variation of the insulin-induced hypoglycemia depends on the time recovery from the glucose fall rather than on lower circulating glucose levels attained following hormone injection. These results underline the importance of considering circadian variations when planning either experimental designs or insulin therapy. This research was supported partly by theConsejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina (CONICET) andComisión de Investigaciones Científicas de la Provincia de Buenos Aires. Member of theCarrera del Investigador (CONICET). Fellow of theCONICET.     

A prospective study of oesophageal 24-h ambulatory pH monitoring in patients with functional dyspepsia

BACKGROUND: The diagnostic utility of 24-h oesophageal ambulatory pH monitoring in patients with functional dyspepsia has not been well established. AIMS: We performed a prospective study of oesophageal pH monitoring in patients with functional dyspepsia in order to assess whether a positive pH test might predict response to proton pump inhibitor therapy in a subset of functional dyspepsia patients. PATIENTS: Forty Helicobacter pylori-negative functional dyspepsia patients (35 males and 5 females, mean age (+/-S.E.M.) of 54+/-2.4 years) with predominantly unspecified dyspepsia subtype and normal distal oesophageal biopsies. METHODS: All subjects were randomised in a double-blind fashion to either omeprazole 20 mg/day or placebo daily for four weeks after 24-h pH monitoring. RESULTS: Twenty-four-hour pH monitoring was abnormal in 9 of the 21 patients (43%) in the omeprazole group and 5/19 (26%) of the placebo group (p=NS). Patients who reported symptomatic improvement on the Gastrointestinal Symptom Rating Scale were no more likely to have abnormal scores on pH monitoring than patients who did not have symptomatic response. CONCLUSIONS: Although approximately one-third of functional dyspepsia patients will have abnormal profiles on 24-h ambulatory oesophageal pH monitoring, an abnormal score does not appear to predict response to proton pump inhibitor therapy in patients with unspecified functional dyspepsia.