Factors that influence induction of gastroesophageal reflux in normal human subjects

Findings from recent studies indicate that transient relaxation of the lower esophageal sphincter (LES) is an important contributory mechanism to spontaneous episodes of gastroesophageal reflux (GER) in normal subjects as well as in patients with reflux esophagitis. Our study aim was to evaluate the interrelationship between reduction of LES pressure and elevation of intraabdominal pressure in the induction of GER in healthy subjects. Seven volunteers were studied supine after gastric loading with 0.1 N HCl. A pH probe recorded acid GER. Leg raising (LR) or abdominal compression (AC) were used as stress maneuvers to increase intraabdominal pressure, either alone or in combination with stimuli that concurrently lowered LES pressure, namely multiple rapid swallows (RS) or intraesophageal balloon distention (BD). Each individual stimulus and stimulus combination was tested three times, giving a total of 24 test maneuvers per subject. The test maneuvers elicited 2-12 GERs in each subject. The GER incidence for single maneuvers was: AC, 0%; LR, 0%; RS, 19%; and BD, 24%. LR in combination with RS or BD did not increase the incidence of GER above that induced by RS or BD alone. In contrast, AC concurrent with RS and BD increased the incidence of GER to 52% and 81%, respectively. For all test conditions, a prerequisite for the occurrence of GER was a fall in LES pressure to a minimal value of 3 mm Hg or less. GER never occurred when LES pressure was greater than or equal to 4 mm Hg, even during intervals of increased intraabdominal pressure.(ABSTRACT TRUNCATED AT 250 WORDS)     

Characterization of Esophageal Striated Muscle in Patients with Achalasia

Many studies have been conducted analyzing the manometric properties of patients with achalasia, but the striated portion of the esophagus has never been analyzed and is often overlooked. We retrospectively reviewed 120 manometric tracings (20 achalasia, 100 controls) performed between 1994 and 1997 and excluded tracings from patients with chronic cough and nutcracker esophagus. The data were assessed for age, sex, symptoms, duration of symptoms, lower esophageal sphincter pressure, gastroesophageal gradient, upper esophageal sphincter pressure, smooth muscle contraction amplitude and duration, striated muscle contraction amplitude and duration, length from upper esophageal sphincter to maximal striated muscle contraction, and esophageal length. The maximum striated muscle contraction amplitude was significantly decreased in achalasia patients with a median amplitude of 45 mm Hg (range 12–95) vs 76 mm Hg (range 30–210) in the control group (P = 0.002). Although the wave forms were similar, the maximum striated muscle contraction duration and the distance from the upper esophageal sphincter in achalasia patients was not significantly different from controls. The length of the esophagus was significantly longer in achalasia patients with a median value of 25 cm (range 21–30) vs 21 cm (range 17–26) in the control group (P < 0.001). Patients with achalasia have significantly lower maximum striated muscle contraction amplitudes and longer esophagi, but the duration of the contractions and the configuration of the wave forms are not different.     

Relationship between straining, transient lower esophageal sphincter relaxation, and gastroesophageal reflux in children

OBJECTIVE: Physical straining such as deep inspiration or coughing may induce gastroesophageal reflux (GER) by overcoming feeble lower esophageal sphincter (LES) pressure. The role of straining as a provocant of GER has not been analyzed systematically in children. It was our aim to examine the contribution of straining to the occurrence of GER with particular attention to its relationship to transient LES relaxations, which are a major mechanism of the occurrence of GER in pediatric patients. METHODS: Concurrent esophageal manometry and pH monitoring was performed for 4 h postprandially in six children with esophagitis (age 9 months to 12 yr). Analysis was performed on isolated single strain episodes, defined as an increased intragastric pressure > 10 mm Hg. When a drop of esophageal pH < 4.0 was noted within 15 sec after any part of a strain, this strain was defined as related to the reflux episode. RESULTS: The median value of basal LES pressure was 10 mm Hg (range 1-18). In all, 134 analyzable strains and 87 analyzable reflux episodes were recorded. Isolated strains were associated with 20 reflux episodes (23%). Reflux was observed more frequently with strains that occurred during transient LES relaxations (12/40) than straining when the LES was contracted (8/94) (p < 0.01). Sustained strain (35%) and inspiratory strain (25%) were the major patterns of straining related to reflux. CONCLUSION: Straining provoked reflux infrequently and simultaneous occurrence of straining and transient LES relaxation was important in determining the occurrence of strain-related reflux in pediatric patients with reflux esophagitis.     

Biomechanical characteristics of the human esophagus

Biochemechanical wall properties of the human esophagus were studied. A probe, with a balloon designed for simultaneous measurement of cross-sectional area and intraluminal pressure, was placed in the esophagus 30 cm from the incisors. Tone was not detected before inflation of the balloon. When the balloon was inflated stepwise with pressures up to 40 cm H₂O (30.7 mm Hg), measurement of cross-sectional area allowed calculation of distensibility and circumferential wall tension. Balloon cross-sectional area increased linearly with increased balloon pressure. Balloon distension induced contractions, both proximal to the balloon and at the site of distension, at a balloon pressure of about 15 cm H₂O (11.5 mm Hg). The cross-sectional area for the threshold for distension induced contractions was 153±12 mm² (diameter 14 mm). At the onset of these contractions, the contraction force was 15–20 cm H₂O (11.5–15.3 mm Hg) and it increased to 47–58 cm H₂O (36.1–44 mm Hg) at a balloon pressure of 20–40 cm H₂O (15.3–30.7 mm Hg). Circumferential wall tension increased with increasing intraluminal pressure in an almost exponential manner. The pressure elastic modulus increased steeply at lower balloon pressures (10–20 cm H₂O) (7.7–11.5 mm Hg), but at higher balloon pressures (20–40 cm H₂O) (15.3–30.7 mm Hg) this increase was less. The circumferential wall tension and wall stiffness of the human esophagus increased with increasing balloon pressure and cross-sectional area. When a threshold is reached, distension induced contractions both proximal and distal to the balloon and at the distension site.This work was supported by a National Institutes of Health grant DK 11242.     

Three-dimensional imaging of the lower esophageal sphincter in healthy subjects and gastroesophageal reflux

The resting pressure and intraabdominal length are the most important factors which determine competence of the lower esophageal sphincter (LES). The intraabdominal sphincter vector volume (ISVV) is a single value which takes into account both of these measurements. Normal values of ISVV and of the total sphincter vector volume (TSVV) were established in 20 normal subjects. The sensitivity and the specificity of ISVV and TSVV were then evaluated in 81 patients with gastroesophageal reflux disease (GERD) and in 19 normal subjects and were compared with the usual stepwise pullback manometry (SPM) measuring the resting pressure of the LES at the respiratory inversion point. The motorized pullthrough technique was used to perform the vector volume procedure. Normal values of ISVV were 1870–10740 mm Hg² × mm, and of TSVV 2200–13110 mm Hg² × mm. The sensitivity of ISVV was 93.8% (p < 0.05), of TSVV 80.2%, and of SPM 81.5%. The specificity of ISVV and TSVV was 89.5% and of SPM 78.9% (not significant). Analysis of the intraabdominal sphincter vector volume is more sensitive than the total sphincter vector volume or standard stationary manometry in establishing a defective LES in patients with GERD. Intraabdominal sphincter vector volume analysis will allow surgeons better to identify patients with a defective LES who may be suitable for antireflux surgery.     

Clinical and manometric findings in benign peptic strictures of the esophagus

To determine the possible factors that may contribute to the development of peptic stricture of the esophagus, clinical and manometric features were compared in patients with symptomatic gastroesophageal reflux and those with peptic strictures of the esophagus. Patients with stricture were older and had a longer duration of heartburn than patients without a stricture. Most importantly, patients with stricture had a more marked decrease in lower esophageal sphincter (LES) pressure, 4.9±0.5 mm Hg, than patients without a stricture, 7.5±0.6 mm Hg, P<0.01. The LES pressure in all patients with stricture was below 8 mm Hg, and did not overlap with normal values. Patients with stricture had either a nonspecific motor abnormality or aperistalsis (64%), compared to patients with symptomatic reflux (32%), P<0.05. Thus, peptic stricture of the esophagus is commonly associated with a long duration of reflux symptoms in patients with a very low LES pressure and esophageal motor disorder.     

Lower esophageal sphincter pressure in Chagas' disease

It is known that lower esophageal sphincter (LES) pressure in patients with idiopathic achalasia is higher than in normal subjects, but in patients with Chagas' disease, who have esophageal disease with similar clinical, manometric, and radiologic results, studies of LES pressure show contradictory findings. We measured the LES pressure in 118 patients with chronic Chagas' disease, 14 patients with idiopathic achalasia, and 50 control subjects using a perfused catheter and the stationary pull-through (SPT) technique. The patients with Chagas' disease had normal esophageal radiologic examination (group A, N=50), delay in esophageal clearance without dilatation (group B, N=41), or delay in esophageal clearance with dilatation (group C, N=27). The LES pressure of Chagas' disease patients of group A (18.6 ±9.1 mm Hg, mean ±SD), group B (17.8 ±9.7mm Hg), and group C (21.6 ±10.1 mm Hg) was lower (P<0.001) than the LES pressure of the controls (24.9 ±10.2 mm Hg). In patients with idiopathic achalasia, the LES pressure (40.7 ±17.8 mm Hg) was higher than in control subjects (P<0.01) and Chagas' disease patients (P<0.001). We conclude that the LES pressure of patients with Chagas' disease tended to be lower than that of control subjects and achalasia patients.Presented in part at the 8th World Congress of Gastroenterology, September 1986, São Paulo, Brazil, and published in abstract form inDig Dis Sci 31:273, 1986.     

Effects of Omeprazole on Mechanisms of Gastroesophageal Reflux in Childhood

Prolonged recordings of esophageal motility haveshown that dynamic changes of lower esophageal sphincter(LES) pressure such as transient LES relaxation and LESpressure drifts are the most common mechanisms underlying gastroesophageal reflux (GER). Thecoexistence of a delayed gastric emptying has also beenreported in a high proportion of patients with refluxdisease. However, not much information is available on the effects of antireflux therapy on thepathogenetic mechanisms of GER. The purpose of thisstudy was to determine in a group of children withsevere reflux disease the effect of omeprazole therapy on motor changes of LES underlying GER as wellas on gastric emptying time. Twenty-two children (medianage: 6.6 years) with GER disease, refractory to combinedranitidine and cisapride administration, entered into an eight-week omeprazole course.Ten subjects with moderate GER disease served ascontrols (median age: 6.0 years). Before and afteromeprazole administration, the following variables were assessed: esophagitis grading, fasting and fedsimultaneous prolonged recording of distal esophagealsphincter pressure (with a sleeve catheter) andintraesophageal pH, LES and esophageal peristalsisamplitude, and gastric emptying time of a mixedsolid-liquid meal (measured with gastric ultrasound). Ascompared to controls, patients showed a higher rate oftransient LES relaxation and LES pressure drift (P <0.01), a reduced amplitude of basal sphincter pressure(P < 0.01) and peristalsis (P < 0.05), and a moreprolonged gastric emptying time (P < 0.05). Afterending omeprazole, there was no significant change inany of the motor abnormalities of the esophagus and ingastric emptying time despite a marked improvement ofsymptoms and esophagitis in all patients. Sixteenpatients were symptomatic when reevaluated on a clinical basis two months after ending therapy. Weconclude that in children with severe GER disease, anabnormally high rate of both transient LES relaxationand LES pressure drift and slow gastric emptying are not affected by omperazole treatment, eventhough esophageal mucosal damage is markedly improved orcured. These abnormalities represent a primary motordisorder and can be implicated in the refractoriness of reflux disease.     

Assessment of the neural defect in a dog with idiopathic megaesophagus

In a dog with megaesophagus, we studied (1) the upper (UES) and lower (LES) esophageal sphincter responses to swallowing, (2) the UES response to intraesophageal balloon distension and acid perfusion, (3) the fasting LES, stomach and upper small bowel motor activity, and (4) the LES response to intraesophageal balloon distension. The findings were compared to those in two normal dogs. In normal dogs, balloon distension (10–40 cc) and acid perfusion (0.1–0.4 N HCl) at 5, 10, and 15 cm distal to the UES produced up to 200% and 100% increases in UES pressure, respectively. Fasting LES activity in these dogs was coupled to the cyclical migrating motor complex (MMC) activity of the stomach and intestine, with phase I, random phase II, and phase III employing 40%, 40%, and 20% of cycle time, respectively. Balloon distension (10–40 cc) at 5, 10, and 15 cm proximal to the LES in phases I, II, and III produced 80–100% relaxation of the sphincter. In the dog with megaesophagus: (1) the UES and LES response to swallowing was normal; (2) balloon distension (10–40 cc) in the upper esophagus produced no significant increase (P>0.05) in UES pressure while acid perfusion (0.1–0.4 N HCl) produced a significant but relatively smaller increase (50%) in UES pressures; (3) phase I MMC activity in this dog was absent or very short in duration (<5% cycle time), the activity mostly alternating between phases II and III (75–80% and 20% cycle time, respectively); and (4) balloon distension in the distal esophagus (up to 80 cc) induced no observable relaxation (<10%) of the LES. Conclusion: The normal UES and LES response to swallowing and the presence of cyclical MMC activity in the LES indicates that the efferent neural pathways, at least to these areas, are intact in the dog with megaesophagus. Absence or decreased response of the UES and LES to intraluminal stimuli suggests that at least the afferent component of the reflex neural pathways is faulty in idiopathic megaesophagus. The location of the defect is yet to be determined.This work was supported by the Medical Research Council of Canada grant MA3353, and the Elsie Watt Foundation.     

Achalasia in the elderly

Clinical and manometric data from 13 elderly subjects with idiopathic achalasia (mean age 79±2 years) were compared with findings from younger subjects with the same disease (n=79) to see if aging altered the presentation and outcome of this motor disorder. Fewer elderly subjects complained of chest pain (27% vs 53%), and the pain was significantly less severe (P<0.01). Other presenting features (including sex, duration of symptoms, and presence and severity of dysphagia) did not differ between the groups. Across all patients, age weakly and inversely correlated with residual postdeglutitive lower esophageal sphincter (LES) pressure (R=–0.34), and residual pressure was significantly lower in the older subjects (8.0±1.3 mm Hg vs 11.9±0.8 mm Hg;P=0.02). No differences in basal LES pressure or esophageal-body contraction amplitudes were present between the groups. Initial success with pneumatic dilation was similar in the two subject groups, but the number of older subjects available for analysis was too small to draw strong conclusions. These results indicate that aging decreases the elevation of LES residual pressure that occurs with achalasia. As elderly achalasia patients also present with less chest pain, the findings may be interrelated.Supported in part by grant AMO7130 from the United States Public Health Service. Dr. Todorczuk is supported by an educational grant from Smith, Kline, and French.     

Prevention of Deleterious Effects of Reperfusion Injury Using One-Week High-Dose Allopurinol

Allopurinol has been widely used to reduce the severity of the reperfusion injury. However, conflicting data have been reported regarding the dosage, the duration of the timing, and the administrative regimen of the drug. The aim of this study was, therefore, to evaluate the effects of short versus long periods of allopurinol pretreatment on the anastomotic healing of intestines, directly after being subjected to ischemia–reperfusion (IR) stress. Furthermore, the effects of an allopurinol pretreatment on the survival rate following IR stress, was also assessed. One hundred thirty-seven male Wistar rats with a median weight of 235 (range, 180–275) g used in the study. In group I (control group, N = 20) superior mesenteric artery (SMA) and collateral vessels were isolated but not occluded. In group II, the profound IR group (PIR, N = 42), the SMA was occluded immediately distal to the aorta with collateral interruption using an atraumatic arterial clip for 30 min. In group III [two days of allopurinol (ALL) pretreatment group, 2ALL, N = 38], allopurinol (100 mg/kg body wt) was given intraperitoneally on a daily basis for two days prior to the experiment. In group IV (seven days of allopurinol pretreatment group, 7ALL, N = 37), the same pretreatment and the allopurinol schedule was performed for seven days before surgery. All animals underwent 3 cm of ileal resection and primary anastomosis, 10 cm proximal to ileocecal valve. Within each group, animals were anesthetized either on the third or seventh postoperative days. Abdominal wound healing, intraabdominal adhesions, anastomotic complications, anastomotic bursting pressure measurements, and bursting site were recorded as were the histopathologic evaluation. No rats in group I, 20 rats in group II, 18 rats in group III, and 7 rats in group IV died (P = 0.0003). Anastomotic dehiscence was found in one of 20 group I, in 11 of 22 in group II, in 9 of 20 in group III, and in 3 of 30 in group IV (P = 0.0003). On the third and seventh days, the median bursting pressures of the anastomosis were determined: 42 and 235 mm Hg in group I, 17 and 105 mm in Hg in group II, 22 and 183 mm Hg in group III, and 36 and 214 mm Hg in group IV (P < 0.0001). The burst occurred at the anastomoses in all animals tested on the third postoperative day, one in group I, six in group II, four in group III and one in group IV on the seventh postoperative day (P < 0.01). All deleterious effects of reperfusion injury on intestinal anastomosis healing, including survival rates and the histopathological parameters, were significantly prevented by seven days, but not two days, of high-dose allopurinol pretreatment.     

Fasting and postprandial mechanisms of gastroesophageal reflux in children with gastroesophageal reflux disease

In order to define the mechanisms of gastroesophageal reflux (GER) in children, we performed simultaneous intraluminal, esophageal motility and pH studies in 24 children with symptomatic reflux and abnormal prolonged pH probe study, ten (group A) without endoscopic and histologic esophagitis, 14 (group B) with endoscopic and histologic esophagitis. Median (ranges) age (years) was 5.0 (6 months-10 years) and 3.0 (6 months-12 years), respectively. Recordings were done for 1 hr before and 1 hr after feeding apple juice (15 ml/kg; pH 4.0). All episodes of GER in group A patients and 77.1% in group B patients were accounted for by abrupt transient lower esophageal sphincter (LES) relaxation (TLESR); 22.9% of reflux events in group B patients occurred during gradual drifts of LES pressure (LESP) to undetectable levels. Esophageal refluxate exposure (mean percentage time with esophageal pH<4.0) the rate of TLESR (number of episodes/hr), and the percentage of TLESRs associated with reflux significantly increased in the fed period both in group A (18.5±5.4%, 6.2±2.65, 87.1%) and in group B (29.7±6.5 7.8±3.05, 84.9%) as compared to the fasting state (group A: 10.8±3.9, 3.9±3.17, 46.1%; group B: 16.1±2.6, 4.14±3.06, 55.17%) (p<0.01). The rate of LESP drifts (number of episodes/hr) was also significantly higher postprandially (4.85±1.24 vs 1.8±0.9,p<0.01); furthermore there was a postfeeding increase of the LESP drift percentage associated with reflux (79.41% vs 46.15%,p<0.01). Residual pressure of TLESRs associated with reflux was significantly lower than that of TLESRs without GER in both groups of patients, during fasting (group A:p<0.01; group B:p<0.05) and fed state (p<0.05), whereas duration of relaxation and LESP in the 1-min period before each TLESR did not discriminate TLESRs associated with reflux from those without reflux. In children with GER disease, TLESR is the most common mechanism of reflux, but gradual LESP drift is associated with more severe disease; the postprandial increase in the esophageal acid exposure is mainly due to increased rate of TLESRs and LESP drifts; degree of sphincter inhibition during TLESRs is a critical factor for the induction of reflux.Presented in part at the 91st Annual Meeting of the American Gastroenterological Association, San Antonio, Texas, May 12–18, 1990.     

A test of gastroesophageal sphincter competence

Gastroesophageal manometrics, using continuously perfused polyvinyl tubes, and acid reflux (pH test) were studied prospectively in 13 patients with, and 14, without symptoms and/or signs of gastroesophageal reflux. Pressures were recorded simultaneously from stomach, gastroesophageal sphincter and distal esophagus at rest and during gradual abdominal compression to 80 mm Hg. Neither the mean resting pressures nor the mean increase in gastric or sphincter pressures, during abdominal compression, were significantly different (P>0.10). Sphincteric yield pressures did not separate the 2 groups. However, the mean esophageal pressure rise was significantly greater (P<0.001) in the symptomatic patients (34±4.5 vs 9.9±3.2 mm Hg). The mean pressure in the stomach, sphincter and esophagus became almost identical in the symptomatic patients—a common cavity occurred between stomach and esophagus. Two symptomatic patients had negative pH but positive common cavity tests. No asymptomatic patient had evidence of either reflux or a positive common cavity test.Supported by the Denver Veterans Administration Hospital Training Grant in Gastroenterology, TR 110, and by the National Institute of Health Training Grant in Gastroenterology, AM 5122.     

胆碱能神经对反流性食管炎食管动力的影响

目的研究内源性胆碱能神经在反流性食管炎食管动力机制异常中的作用.方法经下食管括约肌切开制备反流性食管炎的猫模型,用连续水灌注测压系统检测正常猫及反流性食管炎的猫食管体部动力;用分光光度法分别测定正常猫及反流性食管炎的猫食管中段、远段肌组织中的乙酰胆碱转移酶和乙酰胆碱酯酶活力.结果反流性食管炎组食管远段平均收缩波幅度明显低于正常对照组(P＜0.0001),食管远段传导速度低于正常对照组(P＜0.05);反流性食管炎时食管中段及远段肌组织中乙酰胆碱转移酶活力均低于正常对照组的中段及远段(P＜0.05及P＜0.0001),以远段更明显(P＜0.0001).反流性食管炎组食管中段及远段肌组织中的乙酰胆碱酯酶活力与对照组比较差异均无显著性(P＞0.05).结论反流性食管炎可导致食管远段动力低下,内源性胆碱能神经功能异常是其重要机制之一.     

Hypertensive lower esophageal sphincter: what does it mean?

The hypertensive lower esophageal sphincter (LES) (mean LES pressure greater than 45 mm Hg; LES relaxation greater than 75%; normal peristalsis) is a poorly characterized motility disorder associated with chest pain and dysphagia. Therefore, we carried out a multidisciplinary study to assess esophageal pressures and function in 15 symptomatic hypertensive LES patients (3 men, 12 women; mean age, 53 years). On-line computer analysis showed a significant (p less than 0.05) increase in LES pressure (55.5 versus 14.9 mm Hg) and residual pressure (6.8 versus 1.1 mm Hg) as well as a decrease in percentage of LES relaxation (87 versus 93%) in patients compared with age-matched controls. All patients had normal peristalsis but 7 of 15 had nutcracker esophagus (mean distal amplitude, 216 mm Hg). No patient had evidence of impaired liquid transport on barium esophagram. The emptying of solids as assessed by radionuclide scans was normal in 14 of 15 patients. Of the 12 patients who completed both psychological inventories, nine had elevated scores on scales assessing anxiety and somatization. The heterogenous nature of this disorder is illustrated by a patient with a changeable narrowing in the distal esophagus associated with the transient impaction of a marshmallow. Dysphagia but not chest pain improved after pneumatic dilatation. We conclude that the hypertensive LES is a heterogenous disorder. Despite abnormal LES parameters, most patients have normal esophageal function, and frequent psychological abnormalities may contribute to their report of symptoms. A minority have abnormal esophageal transit.     

Lower esophageal sphincter pressure as an index of gastroesophageal acid reflux

The purpose of this study was to determine the relationship of lower esophageal sphincter (LES) pressure and the volume of acid placed into the stomach required to induce gastroesophageal reflux in man. LES pressure was recorded continuously and by station pull-through by three radially oriented catheters in both symptomatic and asymptomatic subjects during the graded infusions of 0.1 N HCl acid into the stomach. Sumptomatic subjects had a mean LES pressure of 7.5±0.7 mm Hg and refluxed at a volume of 140.0±21.0 ml. Fifty-five percent of asymptomatic subjects refluxed at a mean volume of 380.0±24.7 ml, and had a mean LES pressure of 13.8±0.4 mm Hg. Asymptomatic nonrefluxers at a volume of 500 ml of 0.1 HCL acid had a mean LES pressure of 18.9±1.1 mm Hg. The mean LES pressure and acid volumes showed statistical significance between the three groups (P<0.01). There was an excellent overall correlation between LES pressure and acid volume required to produce reflux in all subjects (r=0.91,P<0.001). Following reflux, asymptomatic but not symptomatic subjects showed a significant increase in LES pressure. These studies suggest that: (1) LES pressure does provide an accurate index of the gastroesophageal antireflux mechanism, provided that acid volume is considered; and (2) asymptomatic subjects showing acid reflux have higher LES pressures, reflux at higher volumes, and develop an LES contractile response after the reflux episode.This work was supported by a grant from the Smith Kline & French Laboratories, Philadelphia, Pennsylvania.     

Identification of Diaphragmatic Crural Component of Gastroesophageal Barrier in the Rat

Manometric assessment of the diaphragmaticcontribution to the human gastroesophageal barrier isdifficult because it overlaps with that of the loweresophageal sphincter. Our aim was to investigate the barrier components in the rat in which thegastroesophageal junction is widely separated from thehiatus. Rats under anesthesia (N = 119) and after musclerelaxation (N = 14) underwent stationary andpull-through perfusion manometry. Inspiratorytransdiaphragmatic pressure gradient was 5.79 ±1.69 mm Hg and lower esophageal sphincter pressure was14.76 ± 8.63 mm Hg. A 13.78 ± 3.13-mmintraabdominal segment of the esophagus was interposed craniallybetween the sphincter and a group of phasic oscillationswith frequency identical to the respiratory rate andpressure of 13.81 ± 6.54 mm Hg, which disappeared after muscle relaxation. Both components of thegastroesophageal barrier in the rat are widely separatedby a long intraabdominal esophagus. This arrangementallows investigation of the behavior of both components under challengingconditions.     

Lower esophageal sphincter pressures in patients of bronchial asthma and its correlation with spirometric parameters: a case-control study

Objectives: The cause–effect relationship between bronchial asthma and gastro-esophageal reflux (GER) is known, but studies have not been able to confirm the improvement of lung function with anti-acid therapy. Hypotensive lower esophageal sphincter (LES) may lead to both acid and non-acid reflux, resulting in asthma symptoms and decreased lung function. The objectives of our study were, firstly, to compare basal LES pressure between adult patients of asthma and normal controls and, secondly, to correlate the basal LES pressure with spirometric parameters in these patients. Methods: Thirty patients, aged between 18 and 65 years, diagnosed as cases of bronchial asthma and 27 healthy controls were included in the study. All the participants were subjected to esophageal manometry after overnight fasting and basal LES pressures were recorded. Then, spirometry was done 2?h after meal and pre- and post-bronchodilator FEV₁, FVC, PEFR were obtained for the asthma group. Results and conclusions: There is significant difference between basal LES pressure in patients of bronchial asthma and control population (8.70?±?2.67?mmHg versus 16.64?±?5.52, p?<?0.0001). 66.67% of the asthma patients have reduced LES pressures (<10?mmHg). The correlation coefficient between basal LES pressure and prebronchodilator FEV₁% predicted is 0.596 (p?<?0.0001, 95% CI 0.3002–0.7872). Obstructive airway impairment in adult patients of bronchial asthma is associated with hypotensive LES. GER, due to hypotensive LES may contribute to deterioration of spirometric parameters in asthma patients.     

Mechanisms of nocturnal gastroesophageal reflux events in obstructive sleep apnea

Purpose  

Obstructive sleep apnea (OSA) is associated with increased nocturnal gastroesophageal reflux (nocturnal GER) events and symptoms. Treatment of OSA with continuous positive airway pressure (CPAP) reduces nocturnal GER in patients with OSA. This study sought to determine the: (1) relationship of nocturnal GER events with apnea/hypopnea and arousal, (2) effect of upper airway obstruction on the barrier function of the lower esophageal sphincter (LES), (3) mechanism of LES failure for each nocturnal GER event and (4) effect of CPAP on LES function during sleep.     

Significantly Reduced Acid Detection at 10 Centimeters Compared to 5 Centimeters above Lower Esophageal Sphincter in Patients with Acid Reflux

Ambulatory pH monitoring of the esophagus is carried out by positioning a pH sensor 5 cm above the lower esophageal sphincter (LES). There are several techniques to locate the LES, and each method has a different margin of error. This work used dual pH sensors to monitor simultaneously at two different levels (5 and 10 cm above the LES) in order to establish the possible magnitude of error that could arise from inaccurate placement of a pH probe. Thirty-four patients with symptoms of gastroesophageal reflux (GER) were studied. They were grouped as 20 patients with pathological reflux (GER group) and 14 patients with physiological reflux, based on a reflux score derived by Johnson and DeMeester for distal esophageal pH monitoring. When the reflux scores were compared, the difference between the two monitoring levels was statistically significant in the GER group ( p < 0.001) but not in the physiological reflux group ( p = 0.09). In the GER group, the difference in the Johnson and DeMeester score accounted for a change in clinical diagnosis in nine of the 20 patients if the pH probe was placed at 10 cm above the upper margin of LES. Proximal reflux episodes (10 cm above LES) were preceded by distal reflux episodes (5 cm above LES) in 97% (878/901) of cases. Accurate probe placement is essential in the diagnosis of GER.