Monitoring the lower oesophageal sphincter: sphinctometer or sleeve?

Two methods have been used to study lower oesophageal sphincter (LOS) function in gastro-oesophageal reflux disease: the sleeve sensor and the sphinctometer. Our aim was to directly compare the sleeve and sphinctometer in vivo. Ten asymptomatic volunteers were intubated with a perfused assembly incorporating a sleeve sensor, a solid-state assembly incorporating a sphinctometer and a pH probe. LOS function was recorded pre- and post-prandially. During basal periods sleeve and sphinctometer readings correlated well both within and between subjects (r2 = 0.89 (P < 0.0001)). However, the sphinctometer relaxed less during swallows (median 42 (interquartile range 27-55)% vs 73 (62-81)% (P < 0.001)), transient LOS relaxations (TLOSR) (50 (40-70)% vs 94 (88-100)% (P < 0.001)) and reflux episodes (67 (59-75)% vs 97 (91-100)% (P = 0.02)). Using criteria derived from 10 dry swallows, the expected relaxation of the sphinctometer during TLOSR was defined. The sphinctometer had an overall sensitivity ranging from 43 to 71% for the detection of TLOSR with 11-22 false positive relaxations, depending on the criteria employed. Sensitivity was particularly poor in those with low basal LOS pressure. The sphinctometer has a lower capacity to register LOS relaxations than the sleeve sensor, which limits its value in studying the pathophysiology of reflux disease.     

The effect of glucagon-induced gastric relaxation on TLOSR frequency

This study aimed to determine the effect of glucagon-induced gastric relaxation on the frequency of transient lower oesophageal sphincter relaxations (TLOSRs). Eight normal subjects (four male, age 18-52 y) were studied after a 6-h fast using a combined manometric barostat assembly. The recording was divided into two 1-h sessions: (1) a baseline period with the barostat set at minimal distending pressure (MDP) + 2 mmHg and (2) a period with continuous glucagon or placebo infusion with barostat set at MDP + 2 mmHg. Patients were studied on two different days and randomly received glucagon (4.8 microg kg(-1) bolus followed by 9.6 microg kg(-1) h(-1) infusion) on 1 day and placebo (saline) on another. Lower oesophageal sphincter (LOS) pressure, frequency of TLOSRs, and barostat bag volumes were determined for both placebo and glucagon infusion. Glucagon induced significant fundal relaxation compared with placebo (P < 0.05) and significantly decreased baseline LEOS pressure (P < 0.05). The frequency of TLOSRs was not altered by glucagon infusion compared with placebo. Despite causing substantial proximal stomach relaxation, glucagon did not increase TLOSR frequency. This suggests that the relevant gastric mechanoreceptors responsible for triggering TLOSRs do not respond to passive elongation.     

Gastro-oesophageal reflux of liquids and gas during transient lower oesophageal sphincter relaxations

Some transient lower oesophageal sphincter relaxations (TLOSRs) are accompanied by gastro-oesophageal reflux and others are not. We aimed to investigate what factors determine the occurrence and type of reflux during TLOSRs. In 12 healthy subjects prolonged high-resolution manometry was performed. Reflux was detected using pH-impedance monitoring. A total of 219 TLOSRs were detected; no differences were observed between the duration of TLOSRs with liquid-containing reflux (20.2 +/- 1.0 s), gas reflux (17.0 +/- 1.0 s) and no reflux (19.0 +/- 1.0 s). Trans-sphincteric pressure gradient was similar in TLOSRs with liquid reflux (1.6 +/- 0.1 kPa), gas reflux (1.5 +/- 0.1 kPa) and no reflux (1.7 +/- 0.3 kPa). Prevalence, duration and amplitude of oesophageal pre-contractions and sphincteric after-contractions were not different for TLOSRs with and without reflux. The total number of TLOSRs decreased significantly from 8.2 +/- 0.8 in the first to 5.7 +/- 0.5 in the second and 4.4 +/- 0.6 in the third 70-min recording period. The number of TLOSRs accompanied by liquid-containing reflux decreased from 4.7 +/- 0.9 to 3.0 +/- 0.4 to 1.6 +/- 0.4, while the numbers of TLOSRs with gas reflux remained unchanged (2.1 +/- 0.6-2.1 +/- 0.7-2.2 +/- 0.6). Besides, time after the meal, no differences were observed in the characteristics of TLOSRs with and without gastro-oesophageal reflux. We conclude that factors, other than TLOSR characteristics, are important of whether or not a TLOSR is reflux-related.     

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

Abstract  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.     

Transient lower oesophageal sphincter relaxations play an insignificant role in gastro-oesophageal reflux to the proximal oesophagus.

Gastro-oesophageal reflux to the proximal oesophagus may cause atypical symptoms of gastro-oesophageal reflux disease (GORD). The motor abnormalities underlying reflux into the proximal oesophagus are still unclear. The aim of this study was to analyse the oesophageal motility during reflux into the proximal oesophagus in a group of healthy subjects and in patients with atypical symptoms of GORD. We concentrated particularly on lower oesophageal sphincter (LOS) activity and transient lower oesophageal sphincter relaxations (TLOSRs). Ten patients (7M, 3F, age 25-51 years) with mild oesophagitis (Savary-Miller grade I-II) and 10 healthy subjects (6M, 4F, age 23-54 years) underwent a 24-h dual pH-metric and manometric recording, using an electronic portable device. This recorded distal and proximal oesophageal pH values, oesophageal body and LOS motility. GORD patients had more distal and proximal reflux (DR and PR) compared with healthy controls (DR P < 0.001; PR P < 0.05). TLOSRs were the most frequent event during reflux into the distal oesophagus, whereas TLOSR frequency was much lower during reflux to the proximal oesophagus in GORD patients and in healthy controls (P < 0.05 and P < 0.01 vs. distal reflux, respectively). A significant relationship between TLOSRs and distal refluxes was present but no relationship with proximal reflux was detected. We conclude that TLOSRs are much less frequent during reflux to the proximal oesophagus than distal oesophageal reflux in patients with mild GORD suffering from atypical manifestations. The mechanism of acid reflux to the proximal oesophagus is unclear.     

Prolonged recording of oesophageal and lower oesophageal sphincter pressure using a portable water-perfused manometric system

The aim of our study was to investigate the recording fidelity of a water-perfused micromanometric catheter with incorporated sleeve combined with a newly developed portable water-perfused manometric system for pharyngeal, oesophageal and lower oesophageal sphincter (LOS) pressure recording. The system's performance was assessed in prolonged recordings in ambulant gastro-oesophageal reflux disease (GORD) patients. Eighty 24-h studies in GORD patients, carried out with the perfused portable manometric system, were evaluated. Twelve of these recordings were analysed in detail in order to compare oesophageal and LOS motor patterns with those described previously. Paired 2-h manometric recordings of the pharynx, oesophagus, LOS and stomach, using the new system and a conventional perfused stationary manometric system, were performed in eight healthy subjects. With the portable manometric system oesophageal contractions, transient LOS relaxations, swallow-associated prolonged LOS relaxations and LOS pressures were recorded with equal fidelity to the conventional manometric system. Recordings obtained with the portable system showed meal-related and diurnal variations in oesophageal and LOS variables that were similar to these found in studies using conventional equipment. The new manometric system, consisting of a perfused micromanometric catheter with incorporated sleeve and a portable perfusion system, enables prolonged studies on oesophageal and LOS motor patterns in ambulant subjects.     

Distinct patterns of oesophageal shortening during primary peristalsis, secondary peristalsis and transient lower oesophageal sphincter relaxation

This study characterized oesophageal shortening during secondary peristalsis and transient lower oesophageal sphincter relaxation (TLOSR) in an attempt to determine its contribution to the opening mechanism. Eight healthy subjects (four males, 26 +/- 1 years) had metal clips affixed at 0, +3, and +8 cm relative to the squamocolumnar junction (SCJ), defining two distal oesophageal segments. Axial clip movement was assessed with concurrent videofluoroscopy and manometry during primary peristalsis, secondary peristalsis and TLOSR. Clip-defined oesophageal segment length change was measured at 0.5-s intervals. The magnitude of the most distal segment shortening was least with TLOSR, greatest with primary peristalsis and intermediate with secondary peristalsis. Conversely, maximal overall oesophageal shortening during TLOSR, evidenced by SCJ movement, was similar to that during primary peristalsis. In 3/12 TLOSRs, the moment of LOS opening and gas reflux was optimally imaged; SCJ excursion was 0.3 +/- 0.1 cm prior to LOS opening and 1.4 +/- 0.7 cm immediately after gas reflux. The segmental pattern of oesophageal shortening was distinct during primary peristalsis, secondary peristalsis and TLOSR. During TLOSR, significant elevation of the SCJ occurred only after LOS opening, suggesting that this was a consequence of oesophageal distension induced by gas reflux rather than a component of the opening mechanism.     

The lower oesophageal sphincter

Abstract  The lower oesophageal sphincter (LOS) is a specialized segment of the circular muscle layer of the distal oesophagus, accounting for approximately 90% of the basal pressure at the oesophago-gastric junction. Together with the crural diaphragm, it functions as an antireflux barrier protecting the oesophagus from the caustic gastric content. During swallowing or belching, the LOS muscle must relax briefly in order to allow passage of food or intragastric air. These swallow-induced and prolonged transient lower oesophageal sphincter relaxations (TLOSRs) respectively result from activation of the inhibitory motor innervation of the sphincter. Both in man and animals, the main neurotransmitter released by the inhibitory neurones is nitric oxide. The two typical examples of dysfunction of the LOS are achalasia and gastro-oesophageal reflux disease (GORD). Achalasia is characterized by reduction or even absence of the inhibitory innervation to the LOS, leading to impaired LOS relaxation with dysphagia and stasis of food in the oesophagus. On the contrary, GORD results from failure of the antireflux barrier, with increased exposure of the oesophagus to gastric acid. This leads to symptoms such as heartburn and regurgitation, and in more severe cases to oesophagitis, Barrett's oesophagus and even carcinoma. To date, TLOSRs are recognized as the main underlying mechanism, and may represent an important target for treatment. More insight in the pathogenesis of both diseases will undoubtedly lead to new treatments in the near future.     

Computer analysis of prolonged lower oesophageal sphincter pressure recordings

The aim of the study was to validate a recently developed computer program for the analysis of prolonged recordings of lower oesophageal sphincter pressure. Thirty 1-hour stretches were selected from sets of 24-h pressure signals recorded from the pharynx, oesophagus, lower oesophageal sphincter (LOS) and stomach in 10 ambulant patients with gastrooesophageal reflux disease. Three experienced investigators visually analysed end-expiratory LOS pressures and transient lower oesophageal sphincter relaxations (TLOSRs), using published criteria. A computer program was developed for calculation of an end-expiratory pressure curve and detection of TLOSRs using the same criteria. Although the results showed an maximum deviation from the mean of 11.1% and 14.8% for manually calculated LOS pressures and visually detected TLOSRs, respectively only 62.1% of the detected TLOSRs were detected by all three observers. LOS pressure as measured by the computer closely approximated the mean of the LOS pressures calculated by the three observers. Although the total number of TLOSRs was comparable to that assessed by visual analysis, the computer detected only 46% of the TLOSRs detected by each observer and 56.8% of the TLOSRs detected by all observers. It is concluded that automated calculation of end-expiratory LOS pressure is feasible and yields reliable results, whereas automated detection of TLOSRs could not be satisfactorily accomplished. Our study showed that improvement of computer algorithms for TLOSR detection is desirable. However, the previously described criteria for detection of TLOSRs are insufficiently precise; further refinement of these criteria will be necessary to reduce the large discrepancies between the outcome of detection of TLOSRs by computer and by humans, and to reduce the equally large discrepancies between the results of detection by different human observers.     

Effect of baclofen on oesophageal motility and transient lower oesophageal sphincter relaxations in GORD patients: a 48-h manometric study

Abstract  Little is known about prolonged effect of baclofen on oesophageal and lower oesophageal sphincter (LOS) motility. We aimed at investigating the oesophageal motility in gastro-oesophageal reflux disease (GORD) patients 24 h before and after the administration of multiple doses of baclofen. Twenty-one GORD patients underwent a 48-h manometry recording the swallows, the oesophageal and the LOS motility. During the second 24-h period, patients received baclofen 10 mg or placebo four times per day in a double-blind randomized fashion. Baclofen increased the LOS basal tone in comparison with baseline ( P  = 0.02), with a concomitant reduction in the number of transient LOS relaxations (TLOSRs) ( P  = 0.01). Moreover, baclofen induced a decrease of the swallows ( P  = 0.02) and of primary oesophageal body waves ( P  = 0.04) with no changes in the amplitude. Multiple doses of baclofen determine a reduction in the number of TLOSRs and an increase in the LOS tone throughout the 24 h. The concomitant decreased number of swallows and of primary peristalsis could depend on the well-known lower amount of reflux episodes induced by the drug. The potential therapeutic effect of baclofen could be expressed not only postprandially, but also in the fasting state when reflux episodes are present as well.     

Influence of different intragastric stimuli on triggering of transient lower oesophageal sphincter relaxation in the dog

Gastro-oesophageal reflux in the dog is mainly caused by transient lower oesophageal sphincter relaxation (TLOSR), the major stimulus for which is distension of the stomach. The possibility that liquid and/or acid sensors in the proximal stomach reduce the incidence and/or shorten the duration of TLOSR was addressed in the present study. Manometric recordings of the pharynx, oesophagus, lower oesophageal sphincter and stomach were made in awake dogs equipped with an oesophagostomy. TLOSRs were induced by insufflation of air or infusion of liquid nutrients with varying pH. Intragastric distension with air provoked TLOSRs with a significantly shorter duration than those seen after distension with liquid (4.3 +/- 0.5 vs 9.6 +/- 0.3 sec; P < 0.05). There were fewer TLOSRs at high intragastric pH (pH 5.0: 3.1 +/- 0.5/90 min) than at low pH (pH 1.5: 5.5 +/- 0.9/90 min, P < 0.05). Successfully propagated peristalsis following a TLOSR was more common after stimulation with liquid than with air. It can be concluded that there are H(+)-sensing mechanisms in the stomach which stimulate triggering of TLOSR. In addition, the reduced duration of TLOSR during air insufflation shows that the physical state of the distending stimulus can affect the patterning of TLOSR.     

Elicitation of transient lower oesophageal sphincter relaxations in response to gastric distension and meal ingestion

The aim of this study was to compare the effect of graded gastric barostat distension and meal-induced fundic relaxation on the elicitation of transient lower oesophageal sphincter relaxation (TLOSR). In 15 healthy subjects, stepwise fundic distension and oesophageal manometry were performed simultaneously. Next, the effect of meal ingestion on proximal stomach volume and lower oesophageal sphincter function was studied. During stepwise barostat distension of the proximal stomach, a significant linear correlation between intragastric pressure (r = 0.91; P < 0.01) and the TLOSR rate during inflation and subsequent deflation (r = 0.96; P < 0.01) was found. A similar relationship was found for volume. In addition, after meal ingestion, the TLOSR rate increased significantly from 1.40 +/- 3 to 5.4 +/- 1.5 h-1 (P < 0.01) and 5.2 +/- 1.7 h-1 (P < 0.01), respectively, during the first and second 30-min postprandially. However, at similar calculated intragastric volumes, barostat distension led to a significantly higher TLOSR rate than the meal. Similarly, distension-induced increase in gastric wall tension, estimated from the measured bag pressure and volume using Laplace's law, was associated with significantly higher TLOSR rates (P < 0.01). In conclusion, the rate of TLOSRs in healthy volunteers is directly related to the degree of proximal gastric distension and pressure-controlled barostat distension is a more potent trigger of TLOSRs than a meal. The latter finding suggests that tension receptor activation is an important stimulus for TLOSRs.     

An experimental model for the study of transient lower oesophageal sphincter relaxation and motor function of the proximal stomach in humans

A simple and reliable experimental model would be useful in human research on new drugs which target transient lower oesophageal sphincter (LOS) relaxation. The aim was to investigate the effect of repeated distensions on the rate of transient LOS relaxation, LOS pressure and motor function of the proximal stomach. Twelve healthy subjects were studied with a multilumen manometric assembly incorporating a sleeve sensor for the LOS and a bag positioned in the proximal stomach and connected to a barostat. Intrabag volume was set at 75% of the threshold for gastric discomfort and maintained for two 30-min distension periods separated by a 45-min washout with the bag deflated. The studies lasted 145 +/- 2 min. The rate of transient LOS relaxations was similar during the two distensions, 3.5;2-4 vs 3;2.5-4 (median;interquartile range) and so was LOS pressure. Baseline intrabag pressure, as a measure of gastric tone, and the number of pressure waves, as a measure of phasic contractions, were also similar, 11.3;9.3-12.3 mmHg vs 10.8;9.3-12.5 mmHg and 16;13-28 mmHg vs 19;15-29 mmHg, respectively. Our model allows to perform 1-day studies which can assess two experimental conditions on transient LOS relaxations and motor function of the proximal stomach within an acceptable time span.     

Reproducibility of meal-induced transient lower oesophageal sphincter relaxations in patients with gastro-oesophageal reflux disease

AIM: To calculate the number of subjects required in trials investigating drugs reducing the number of transient lower oesophageal sphincter relaxations (TLOSRs), the inter- and intra-individual variability of TLOSRs were determined, using meal ingestion as a trigger of TLOSRs and reflux. METHODS: A total of 23 gastro-oesophageal reflux disease (GORD) patients with no to grade B oesophagitis and a hiatal hernia < or =3 cm underwent oesophageal manometry and pHmetry 1 h before and 3 h after ingestion of a solid meal on two separate days approximately 4 weeks apart. Reflux episodes and the underlying mechanisms and the number of TLOSRs were evaluated. RESULTS: The number of TLOSRs, reflux episodes and % time with pH < 4 after meal ingestion did not differ significantly between the two sessions. The intra-individual variation of TLOSRs in the 3 h postprandial period (24.4) was smaller compared with the inter-individual variation (47.5). Transient lower oesophageal sphincter relaxations were the predominant cause of reflux accounting for 61 +/- 7 and 70 +/- 5% of the reflux episodes in visits 1 and 2, respectively. CONCLUSIONS: These data for the first time provide information on the variability of TLOSRs and reflux evoked by meal ingestion, which is of crucial importance for the design and power calculations of future clinical studies evaluating the efficacy of new drugs targeting TLOSRs.     

Quantification of the oesophageal peristaltic reflex in man

Abstract The peristaltic reflex represents the basis of peristalsis and has two components, ascending contraction above and descending relaxation below the site of distension. Studies of the two components of the reflex in the human oesophagus performed by concurrent monitoring of oesophageal body and lower oesophageal sphincter (LOS) motility are lacking. We investigated the peristaltic reflex in eight healthy volunteers (aged 19–25 years; five male, three female) by two series of eight graded (3–10 mL) balloon distensions performed 11 cm above the LOS, monitoring motor activity in the oesophageal body both above and below the balloon and in the LOS (sleeve sensor). During balloon distension both ascending contraction, as assessed by contractile activity above the balloon, and descending relaxation, as assessed by LOS relaxation, increased linearly with increasing inflation volumes (r = 0.6 and r = 0.8, respectively, both P < 0.0001). The threshold for descending relaxation was lower than that for ascending contraction. The contractile response of the body below the balloon was always lower than above the balloon and occurred with a higher (P < 0.05) frequency at 6 and 7 mL compared to 3, 4 and 10 mL. After balloon deflation an oesophageal contraction, usually accompanied by an LOS contraction, occurred with increasing frequency as the balloon volume increased. Our experimental model allows detailed assessment of the two components of the peristaltic reflex in the human oesophagus in vivo and should prove useful in future studies on the physiology and pathophysiology of this reflex.     

Relationship between the mechanism of gastro-oesophageal reflux and oesophageal acid exposure in patients with reflux disease

Abstract  This study investigated the relationship between the oesophageal acid exposure time and the underlying manometric motor events in patients with gastro-oesophageal reflux disease (GORD). In 31 patients, 3-hour oesophageal motility and pH were measured after a test meal. Ten patients underwent 24-hour ambulatory manometry and pH recording. In the 3-hour postprandial study, of 367 reflux episodes 79% was associated with a transient lower oesophageal sphincter relaxation (TLOSR), 14% with absent basal lower oesophageal sphincter (LOS) pressure and the remaining 7% with other mechanisms, representing 62, 28 and 10% of the acid exposure time, respectively. Acid reflux duration per motor mechanism was longer for absent basal LOS pressure than for TLOSR (189 ± 23 s and 41 ± 5 s, respectively, P  < 0.001). In the 24-hour ambulatory study, the contribution of TLOSRs to reflux frequency vs acid exposure time were 65 vs 54% interprandially and 74 vs 53% after the meal. During the night, absence of basal LOS pressure accounted for 36% of reflux events representing 71% of acid exposure time. In conclusion, the duration of oesophageal acid exposure following a TLOSR is shorter than reflux during absent basal LOS pressure. TLOSRs are, the major contributor to oesophageal acid exposure during the day. At night, however, reflux during absent basal LOS pressure is the major contributor to acid exposure.     

Multiple rapid swallowing in idiopathic achalasia: evidence for patients' heterogeneity.

In order to evaluate the function of inhibitory neural pathways in achalasia, we compared the response of the oesophageal body and lower oesophageal sphincter (LOS) to single swallows (SS) and multiple rapid swallowing (MRS) in 20 consecutive patients with untreated idiopathic achalasia (10 men, aged 23-81 years) and in 20 control patients without dysphagia (nine men, aged 31-73 years), using sleeve manometry; 277 SS and 85 MRS were analysed. In the control group, MRS inhibited motor activity in the oesophageal body and induced a slightly lower (P < 0.05) nadir LOS pressure compared with SS. In the achalasia patients, MRS induced a variable response: eight patients had simultaneous motor activity during all MRS although onset was delayed compared with SS [median (interquartile range), 3.5 s (1.7-6.1) vs 1.4 s (0.8-3.9); P < 0.05], whereas eight patients showed motor inhibition which occurred during all MRS in four of them, and the remaining four had no motor activity both after SS and during MRS. Overall MRS did not decrease nadir LOS pressure compared with SS [12 mmHg (5-20) vs 16 mmHg (7-22); P > 0.1]; however, it induced complete LOS relaxation in three of the patients. MRS gives further evidence of functional heterogeneity among achalasia patients.     

Upper sphincter function during transient lower oesophageal sphincter relaxation (tLOSR); it is mainly about microburps

Transient lower oesophageal sphincter relaxations (tLOSRs) are both a dominant mechanism of reflux and an element of the belch reflex. This study aimed to analyse the interplay between reflux and upper oesophageal sphincter (UOS) activity during meal-induced tLOSRs. Fifteen normal subjects were studied with a solid-state high-resolution manometry assembly positioned to record from the hypopharynx to the stomach and a catheter pH electrode 5 cm above the LOS. Subjects ate a 1000-calorie high-fat meal and were monitored for 120 min in a sitting posture. The relationship among tLOSRs, common cavities, pressure changes within the oesophagus and UOS contractile activity were analysed. A total of 218 tLOSRs occurred among the 15 subjects. The majority (79%) were coupled with UOS relaxation and 84% (145/173) of these occurred in association with a common cavity. Upper oesophageal sphincter relaxation was usually preceded by a pressure change in the oesophagus; however, some relaxations (16%) occurred without a discernable increase in pressure or before the pressure increase began. Acid reflux did not appear to play a role in determining UOS response to tLOSRs. The majority of post-prandial tLOSRs were associated with brief periods of UOS relaxation, likely permissive of gas venting (microburps). Intraoesophageal pressure changes likely modulate this UOS response; however, an anticipatory characteristic was evident in some subjects. Whether or not GORD patients with extra-oesophageal symptoms exhibit an exaggeration of the UOS relaxation response during reflux is yet to be determined.     

Motor events underlying gastro-oesophageal reflux in ambulant patients with reflux oesophagitis

Abstract Information on the mechanism of gastro-oesophageal reflux in patients with reflux disease is limited largely to studies in resting recumbent subjects. Evidence exists that both posture and physical activity may influence reflux. The aim of this study was to investigate reflux mechanisms in ambulant patients with reflux oesophagitis. Concurrent ambulatory oesophageal manometry and pH monitoring were performed in 11 ambulant patients with erosive oesophagitis. Lower oesophageal sphincter (LOS) pressure was monitored with a perfused sleeve sensor. Recordings were made for 90 min before and 180 min after a meal. At set times patients sat in a chair or walked. LOS pressure was ≤2 mmHg at the time of reflux for 98% of reflux episodes. Transient LOS relaxation was the most common pattern overall and the predominant pattern in seven patients, whilst persistently absent basal LOS pressure was the most common pattern in four patients. The pattern of LOS pressure was not altered by the presence of hiatus hernia or by walking. Straining occurred at the onset of 31% of acid reflux episodes but often followed the development of an oesophageal common cavity. The occurrence of straining was not influenced by walking. In ambulant patients with reflux oesophagitis: (1) LOS pressure is almost always absent at the time of reflux, usually because of transient LOS relaxation, (2) persistently absent basal LOS pressure is an important mechanism of reflux in a few patients, (3) straining may help to induce acid reflux in a variable proportion of occasions and may in some instances be a response to gas reflux, and (4) walking does not influence the occurrence of reflux or its mechanisms.     

Mechanisms of gastro-oesophageal reflux in the lateral decubitus positions

Gastro-oesophageal reflux is more common in the right than in the left lateral position but the reasons why are not well understood. We have therefore studied the mechanisms underlying reflux in the lateral decubitus positions in patients with reflux disease. Fifteen patients with symptomatic reflux and excessive oesophageal acid exposure were studied (nine male, age 25-63 years). Each was intubated with a perfused manometric assembly, incorporating a Dent sleeve, and a pH probe. Following a 30-min basal period, a 400-kCal meal was infused into the stomach and patients were studied for 60 min in each lateral position. Following infusion of the meal, lower oesophageal sphincter (LOS) pressure fell and transient LOS relaxation (TLOSR) frequency increased. Acid reflux episodes were more common in the postprandial period (fasting 0 (0-6) h, first postprandial hour 1 (0-9) h, P = 0.0002, second postprandial hour 1 (0-22) h, P = 0.02) and occurred more than twice as often in the right lateral position (right 3 (0-22) h, left 0 (0-10) h, P = 0.01). However, TLOSRs, swallow-related relaxations and low basal LOS pressures were equally common in both lateral positions. In patients with reflux disease, postprandial reflux is twice as common in the right lateral position. This does not relate to differences in gastro-oesophageal junctional pressure, suggesting that other aspects of barrier function or differences in the intragastric distribution of chyme may be important.