The mechanisms associated with reflux episodes in ambulant subjects with gastro-esophageal reflux disease

BACKGROUND

The mechanisms associated with gastro-esophageal reflux (GER) episodes were studied using combined High-resolution Impedance Manometry (HRIM) and pH monitoring in ambulant subjects with different patterns of GERD.

METHODS

Sixteen subjects with mild-moderate esophagitis (Los Angeles (LA) grade A&B) (group A) and 11 subjects with severe esophagitis (LA grade C&D) or Barrett's esophagus (BE) were studied before and after a meal, resting, while walking, and during standardized exercise, using a HRIM and a pH probe.

KEY RESULTS

Post-prandial acid GER episodes were more common in group B (median 10 range (3-18) vs A (6.5 (0-18), p = 0.048). Postprandial acid clearance time was much longer in group B (median 0.71( 0.07-2.66 min) vs A (0.17 (0.04-2.44 min), p = 0.02). Transient lower esophageal sphincter relaxation (TLESR) was the most frequent mechanism associated with GER episodes in both groups. Post-prandial TLESRs with GER were more common in group B (median 17 (9-24) vs A 13.5 (7-34), p = 0.014), particularly during exercise (B 8 (6-9) vs A 6 (5-6.8), p = 0.007). Post-prandially TLESR with acid reflux increased during exercise in both groups (A rest median 2.4 (0-6.4) per hour vs exercise 4.7 (0-17.3), p = 0.005 and B 4 (0.8-9.6) vs 5.3 (2.7-13.3) per hour, p = 0.045).

CONCLUSIONS AND INFERENCES

TLESR was the most common mechanism associated with reflux episodes in all subjects. Acid reflux episodes were more common in subjects with severe esophagitis or BE and esophageal acid clearance was much slower. Post-prandial exercise increased TLESR with acid reflux and GERD patients should be encouraged to avoid exercise immediately after a meal.

The mechanisms associated with reflux episodes in ambulant subjects with gastro-esophageal reflux disease

BACKGROUND

The mechanisms associated with gastro-esophageal reflux (GER) episodes were studied using combined High-resolution Impedance Manometry (HRIM) and pH monitoring in ambulant subjects with different patterns of GERD.

METHODS

Sixteen subjects with mild-moderate esophagitis (Los Angeles (LA) grade A&B) (group A) and 11 subjects with severe esophagitis (LA grade C&D) or Barrett's esophagus (BE) were studied before and after a meal, resting, while walking, and during standardized exercise, using a HRIM and a pH probe.

KEY RESULTS

Post-prandial acid GER episodes were more common in group B (median 10 range (3-18) vs A (6.5 (0-18), p = 0.048). Postprandial acid clearance time was much longer in group B (median 0.71( 0.07-2.66 min) vs A (0.17 (0.04-2.44 min), p = 0.02). Transient lower esophageal sphincter relaxation (TLESR) was the most frequent mechanism associated with GER episodes in both groups. Post-prandial TLESRs with GER were more common in group B (median 17 (9-24) vs A 13.5 (7-34), p = 0.014), particularly during exercise (B 8 (6-9) vs A 6 (5-6.8), p = 0.007). Post-prandially TLESR with acid reflux increased during exercise in both groups (A rest median 2.4 (0-6.4) per hour vs exercise 4.7 (0-17.3), p = 0.005 and B 4 (0.8-9.6) vs 5.3 (2.7-13.3) per hour, p = 0.045).

CONCLUSIONS AND INFERENCES

TLESR was the most common mechanism associated with reflux episodes in all subjects. Acid reflux episodes were more common in subjects with severe esophagitis or BE and esophageal acid clearance was much slower. Post-prandial exercise increased TLESR with acid reflux and GERD patients should be encouraged to avoid exercise immediately after a meal.

Sleep and Nocturnal Gastroesophageal Reflux: An Update

Nocturnal gastroesophageal reflux has been associated with poor sleep quality. Normal physiological adaptations of the aerodigestive system to sleep prolong and intensify nocturnal reflux events. This occurrence leads to sleep disruption, as well as to esophageal, laryngeal, and laryngopharyngeal reflux. Controversy exists on whether OSA and nocturnal reflux are causally linked or merely associated because of shared risk factors. Advances in diagnostic technology have provided new insights into gastroesophageal reflux and the mechanisms of nocturnal reflux during sleep. This update reviews new data on causal links between sleep and gastroesophageal reflux disease.

Validation of criteria for the definition of transient lower esophageal sphincter relaxations using high-resolution manometry

BACKGROUND

Criteria for transient lower esophageal sphincter relaxations (TLESRs) are well-defined for Dentsleeve manometry. As high-resolution manometry (HRM) is now the gold standard to assess esophageal motility, our aim was to propose a consensus definition of TLESRs using HRM.

METHODS

Postprandial esophageal HRM combined with impedance was performed in 10 patients with gastroesophageal reflux disease. Transient lower esophageal sphincter relaxations identification was performed by 17 experts using a Delphi process. Four investigators then characterized TLESR candidates that achieved 100% agreement (TLESR events) and those that achieved less than 25% agreement (non-events) after the third round. Logistic regression and decision tree analysis were used to define optimal diagnostic criteria.

KEY RESULTS

All diagnostic criteria were more frequently encountered in the 57 TLESR events than in the 52 non-events. Crural diaphragm (CD) inhibition and LES relaxation duration >10 seconds had the highest predictive value to identify TLESR. Based on decision tree analysis, reflux on impedance, esophageal shortening, common cavity, upper esophageal sphincter relaxation without swallow and secondary peristalsis were alternate diagnostic criteria.

CONCLUSION & INFERENCES

Using HRM, TLESR might be defined as LES relaxation occurring in absence of swallowing, lasting more than 10 seconds and associated with CD inhibition.

Studies on the regulation of transient lower esophageal sphincter relaxations (TLESRs) by acid in the esophagus and stomach

Transient lower esophageal sphincter relaxation (TLESR) is the major mechanism of gastroesophageal reflux, but the regulation of TLESR by stimuli in the esophagus is incompletely understood. We have recently reported that acid infusion in the esophagus substantially (by 75%) increased the number of meal-induced TLESR in healthy subjects. We concluded that the TLESR reflex triggered by gastric distention with meal was enhanced by the stimulation of esophageal nerves by acid. However, the possibilities that the acid infused into the esophagus acts after passing though lower esophageal sphincter in stomach to enhance TLESR, or that the acid directly initiates TLESR from the esophagus were not addressed. Here, we evaluated the effect of acid infusion into the proximal stomach on meal-induced TLESR (study 1) and the ability of acid infusion into the esophagus to initiate TLESR without prior meal (study 2). We analyzed TLESRs by using high-resolution manometry in healthy subjects in paired randomized studies. In study 1, we found that acid infusion into the proximal stomach did not affect TLESRs induced by standard meal. The number of meal-induced TLESRs following the acid infusion into the proximal stomach was similar to the number of meal-induced TLESRs following the control infusion. In study 2, we found that acid infusion into the esophagus without prior meal did not initiate TLESRs. We conclude that the increase in the meal-induced TLESRs by acid in the esophagus demonstrated in our previous study is not attributable to the action of acid in the stomach or to direct initiation of TLESR from the esophagus by acid. Our studies are consistent with the concept that the stimuli in the esophagus can influence TLESRs. The enhancement of TLESR by acid in the esophagus may contribute to pathogenesis of gastroesophageal reflux in some patients.

Acid infusion into the esophagus increases the number of meal-induced transient lower esophageal sphincter relaxations (TLESRs) in healthy volunteers

BACKGROUND

Transient lower esophageal sphincter relaxation (TLESR) is the major mechanism of gastroesophageal reflux (GER) but the regulation of TLESR by stimuli in the esophagus is incompletely understood. If stimuli in the esophagus can influence TLESR, then such regulation may perpetuate or limit GER. We addressed the hypothesis that acid in the esophagus enhances TLESRs.

METHODS

We evaluated the effect of acid infusion into the distal esophagus on TLESRs evoked by a standard meal in a paired randomized study in healthy subjects. TLESRs were evaluated by using high resolution manometry (HRM).

KEY RESULTS

We found that acid in the esophagus enhanced meal-induced TLESRs. Compared to control infusion the number of TLESRs (median [interquartile range]) was increased during 2 h following the acid infusion (11 [9-14] vs 17 [12.5-20], p < 0.01). The average duration of individual TLESRs was not affected. The time-course analysis revealed that a robust increase in TLESRs occurred already in the first hour when the number of TLESRs nearly doubled (6 [5.5-7.5] vs 11 [7.5-12.5], p < 0.05). In contrast to the enhancement of TLESRs, the number of swallows was not changed.

CONCLUSIONS & INFERENCES

The acid infusion into the esophagus increases the number of meal-induced TLESRs in healthy subjects. Our results provide evidence for the concept that the stimuli in the esophagus can influence TLESRs. The regulation of TLESR by stimuli in the esophagus may contribute to pathogenesis of GER in some patients.

Mechanism of UES relaxation initiated by gastric air distension

The aim of this study was to determine the mechanism of initiation of transient upper esophageal sphincter relaxation (TUESR) caused by gastric air distension. Cats (n = 31) were decerebrated, EMG electrodes were placed on the cricopharyngeus, a gastric fistula was formed, and a strain gauge was sewn on the lower esophageal sphincter (n = 8). Injection of air (114 ± 13 ml) in the stomach caused TUESR (n = 18) and transient lower esophageal sphincter relaxation (TLESR, n = 6), and this effect was not significantly (P > 0.05) affected by thoracotomy. Free air or bagged air (n = 6) activated TLESR, but only free air activated TUESR. Closure of the gastroesophageal junction blocked TUESR (9/9), but not TLESR (4/4), caused by air inflation of the stomach. Venting air from distal esophagus during air inflation of the stomach prevented TUESR (n = 12) but did not prevent air escape from the stomach to the esophagus (n = 4). Rapid injection of air on the esophageal mucosa always caused TUESR (9/9) but did not always (7/9) cause an increase in esophageal pressure. The time delay between the TUESR and the rapid air pulse was significantly more variable (P < 0.05) than the time delay between the rapid air pulse and the rise in esophageal pressure. We concluded that the TUESR caused by gastric air distension is dependent on air escape from the stomach, which stimulates receptors in the esophagus, but is not dependent on distension of the stomach or esophagus, or the TLESR. Therefore, the TUESR caused by gastric air distension is initiated by stimulation of receptors in the esophageal mucosa.

Impedance-high resolution manometry analysis of patients with nonerosive reflux disease

BACKGROUND & AIMS

Transient lower esophageal sphincter relaxations (TLESRs) contribute to episodes of reflux. Few studies have assessed the frequencies or compositions of TLESRs and reflux episodes in patients with reflux disease. We used combined high-resolution manometry and impedance monitoring to analyze reflux episodes and esophageal motility in these patients, compared with those of healthy individuals.

METHODS

We evaluated the frequency of TLESRs and the relationship between the reflux pattern and esophageal pressures during TLESRs in 14 patients with nonerosive reflux disease (NERD) and 11 controls. Study participants underwent combined high-resolution manometry and impedance monitoring before and 60 minutes after a solid and liquid meal. The diagnosis of NERD was confirmed by a 24-hour pH impedance test.

RESULTS

The frequency of TLESRs did not differ between patients with NERD and controls. In patients with NERD, TLESRs were associated more often with reflux episodes than in controls (93% ± 6% vs 66% ± 19%; P < .05). Patients with NERD had a higher percentage of pure liquid reflux episodes (33% ± 15% vs 10% ± 2%; P < .05), whereas controls had a higher percentage of mixed reflux episodes (45% ± 16% vs 67% ± 17% in patients with NERD; P < .05). Patients with NERD also had a higher percentage of reflux (liquid and mixed) associated with common cavities (74% ± 18% vs 50% ± 20% in controls; P < .05).

CONCLUSIONS

In contrast to previous studies, we found that TLESRs are associated more often with reflux in patients with NERD than control subjects; this association increases when only liquid and mixed refluxes are considered. These findings indicate that factors involved in the occurrence of reflux in patients with NERD during TLESRs are different from those in healthy subjects.

The spectrum of achalasia: lessons from studies of pathophysiology and high-resolution manometry

High-resolution manometry and recently described analysis algorithms, summarized in the Chicago Classification, have increased the recognition of achalasia. It has become apparent that the cardinal feature of achalasia, impaired lower esophageal sphincter relaxation, can occur in several disease phenotypes: without peristalsis, with premature (spastic) distal esophageal contractions, with panesophageal pressurization, or with peristalsis. Any of these phenotypes could indicate achalasia; however, without a disease-specific biomarker, no manometric pattern is absolutely specific. Laboratory studies indicate that achalasia is an autoimmune disease in which esophageal myenteric neurons are attacked in a cell-mediated and antibody-mediated immune response against an uncertain antigen. This autoimmune response could be related to infection of genetically predisposed subjects with herpes simplex virus 1, although there is substantial heterogeneity among patients. At one end of the spectrum is complete aganglionosis in patients with end-stage or fulminant disease. At the opposite extreme is type III (spastic) achalasia, which has no demonstrated neuronal loss but only impaired inhibitory postganglionic neuron function; it is often associated with accentuated contractility and could be mediated by cytokine-induced alterations in gene expression. Distinct from these extremes is progressive plexopathy, which likely arises from achalasia with preserved peristalsis and then develops into type II achalasia and then type I achalasia. Variations in its extent and rate of progression are likely related to the intensity of the cytotoxic T-cell assault on the myenteric plexus. Moving forward, we need to integrate the knowledge we have gained into treatment paradigms that are specific for individual phenotypes of achalasia and away from the one-size-fits-all approach.

Chronic cough: an update

Cough persisting beyond 8 weeks (ie, chronic cough) is one of the most common reasons for an outpatient visit. A protracted cough can negatively affect one's quality of life by causing anxiety, physical discomfort, social isolation, and personal embarrassment. Herein, the anatomy and physiology of the cough reflex are reviewed. Upper airway cough syndrome, asthma, eosinophilic bronchitis, and gastroesophageal reflux disease account for most chronic cough after excluding smoking, angiotensin-converting enzyme inhibitor use, and chronic bronchitis. Many patients have more than one reason for chronic cough. Treating the underlying cause(s) resolves cough in most instances. There are some coughs that seem refractory despite an extensive work-up. The possibility of a hypersensitive cough reflex response has been proposed to explain these cases. Several clinical algorithms to evaluate chronic cough are presented.

Transient lower oesophageal sphincter relaxation in achalasia: everything but LOS relaxation

In conducting clinical high-resolution oesophageal pressure topography (HROPT) studies we observed that after subjects sat upright between series of supine and upright test swallows, they frequently had a transient lower oesophageal sphincter relaxation (TLOSR). When achalasia patients were studied in the same protocol, they exhibited a similar HROPT event leading to the hypothesis that achalasics had incomplete TLOSRs. We reviewed clinical HROPT studies of 94 consecutive non-achalasics and 25 achalasics. Studies were analyzed for a TLOSR-like event during the study and, when observed, that TLOSR-like event was characterized for the degree and duration of distal oesophageal shortening, the degree of LOS relaxation, associated crural diaphragm (CD) inhibition, oesophageal pressurization and upper oesophageal sphincter (UOS) relaxation. About 64/94 (68%) non-achalasics and 15/24 (63%) of achalasics had a pressure topography event after the posture change characterized by a prolonged period of distal oesophageal shortening and/or LOS relaxation. Events among the non-achalasics and achalasics were similar in terms of magnitude and duration of shortening and all were associated with CD inhibition. Similar proportions had associated non-deglutitive UOS relaxations. The only consistent differences were the absence of associated LOS relaxation and the absence of HROPT evidence of reflux among the achalasics leading us to conclude that their events were incomplete TLOSRs. Achalasic patients exhibit a selective defect in the TLOSR response suggesting preservation of all sensory, central and efferent aspects of the requisite neural substrate with the notable exception of LOS relaxation, a function of inhibitory (nitrergic) myenteric plexus neurons.

Terminating motor events for TLESR are influenced by the presence and distribution of refluxate

Transient lower esophageal sphincter relaxation (TLESR) is frequently associated with reflux events and terminates with a primary or secondary peristaltic wave. However, it is unclear whether the presence and properties of the refluxate affect TLESR-termination events. The aims of this study were to determine the pattern of terminating esophageal motor activity after TLESR in healthy subjects and factors affecting the type of terminating motor event. Fifteen healthy subjects (7 men, age 18-56) were studied. High-resolution manometry and impedance/pH monitoring were performed simultaneously in supine position for 2 h after subjects took a 1,000-kcal meal (Awake Study). This procedure was repeated during the night under polysomnographic recording for 6-8 h after consuming a 1,000-kcal meal (Sleep Study). We categorized three types of TLESR-terminating motor events, primary peristalsis (PP), full secondary contraction (FSC), which propagated the entire esophagus, and partial secondary contractions (PSC), which started distal to the upper esophageal sphincter. Overall, 289 TLESR events were found. The percentages of TLESR events terminated by PP, FSC, and PSC were 22%, 14%, and 64%, respectively. TLESR events terminated by PP were less likely to be accompanied by reflux events. TLESR events terminated by FSC were significantly more likely to have evidence for proximal esophageal reflux and esophago-pharyngeal reflux. Findings were similar in awake and sleep states. We concluded that, in healthy recumbent subjects, the most common TLESR-termination event is a secondary contraction, rather than PP. Presence and distribution of the refluxate is a major influence on the type of terminating contraction.