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.     

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.     

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.     

Effects of wine on lower oesophageal sphincter pressure and oesophageal pH*

Abstract Eleven volunteers received 300 ml white wine, an ethanol solution and tap water to compare the effects of these beverages on lower oesophageal sphincter pressure and gastro-oesophageal reflux. A continuous measurement of sphincter pressure and oesophageal pH was performed one hour before and after ingestion. A significant increase in fraction of time pH<4 (P < 0.01 vs ethanol, P < 0.001 vs water) coincident with a significant decrease in sphincter pressure (P < 0.01) was observed after the intake of wine, The duration of transient sphincter relaxations (P < 0.05) as well as the duration of reflux episodes (P < 0.001) were significantly prolonged, its frequencies were not significantly enhanced. Reflux occurred almost exclusively during complete sphincter relaxations after the intake of ethanol and water, whereas an increase in ‘stress reflux’ and the occurrence of ‘free reflux’ was observed after ingestion of wine (P < 0.001). It is concluded that this change in reflux pattern is related to the depressive effect of wine on lower oesophageal sphincter pressure. Pure ethanol is not responsible for the effects of wine.     

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.     

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.     

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.     

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.     

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.     

Comparison of two techniques for lower oesophageal sphincter manometry: sleeve and sphinctometer

We have compared the sphinctometer with the water-perfused sleeve (gold standard) for measurement of lower oesophageal sphincter (LOS) characteristics by simultaneous recording. LOS pressure and transient LOS relaxations (TLOSR) measured by sleeve and sphinctometer in 11 healthy volunteers showed identical patterns. However, output of the sphinctometer was significantly (P < 0.01) lower than output of the sleeve. A total of 249 TLOSR were recorded. Of these, 176 TLOSR were identified by both sleeve and sphinctometer, 50 TLOSR were identified by sleeve alone and 23 TLOSR by sphinctometer alone. Due to the lower pressure output of the sphinctometer, 29 LOS relaxations did not reach criteria to qualify as TLOSRs. When TLOSR criteria were adjusted for sphinctometer pressure measurements, the number of TLOSRs identified by both sleeve and sphinctometer increased from 176 to 205. In conclusion, in healthy volunteers the sphinctometer registers TLOSR with results comparable with sleeve recording. However at low LOS pressures, the number of TLOSR is underscored by the sphinctometer.     

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.     

Characterization of intraluminal impedance patterns associated with gas reflux in healthy volunteers

Abstract  Multichannel intraluminal impedance (MII) recording allows assessment of flow through the oesophagus and differentiation between liquid and gas contents. Existing MII criteria for recognition of gas gastro-oesophageal reflux (GOR) have not been validated during known gas GOR in humans. Aims: (i) Characterize MII patterns of known gas GOR and optimize criteria. (ii) Clarify interrelationships between magnitude of maximal impedance change, luminal diameter and electrode-mucosa contact. Ten healthy volunteers (six male, 21–37 years) were studied using an oesophageal MII-manometry catheter. After catheter placement, subjects were asked to drink 600 mL of carbonated soft drink. Recordings were made for 20 min and the protocol repeated. Reported belches confirmed manometrically (triggered by transient lower oesophageal sphincter relaxations) were included for analysis. Those episodes were compared against commonly used criteria. Another five subjects (three male, 26–52 years) underwent simultaneous MII and videofluoroscopy using the same protocol. Videofluoroscopic images were analyzed for luminal diameter and the presence of electrode–mucosa contact. All analyzed gas GOR episodes ( n  = 88) were associated with a pattern of impedance rise which was either retrograde (62.5%), synchronous (19.3%) or antegrade (18.2%). Depending on the exact criteria used, sensitivity ranged from 33% to 75%. A multivariate regression model including luminal diameter and the presence of electrode-mucosa contact as independent factors accounted for 53% of all variation in impedance changes. In conclusion, a significant number of gas GOR episodes does not meet criteria for their recognition. New criteria are proposed to include specific antegrade patterns of impedance rise. Luminal diameter and the extent of contact between the oesophageal mucosa and MII-electrodes influence the magnitude and patterning of impedance change.     

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.     

Relationships between air swallowing, intragastric air, belching and gastro-oesophageal reflux

BACKGROUND: With each swallow a certain amount of air is transported to the stomach. The stomach protects itself against excessive distention by swallowed air through belching (gas reflux). The mechanism of belching (transient lower oesophageal sphincter relaxation) is also one of the mechanisms underlying gastro-oesophageal reflux. AIM: To investigate whether swallowing of air leads to an increase in size of the intragastric air bubble and to gastro-oesophageal reflux. METHODS: Multichannel intraluminal impedance measurement was used to quantify the incidence of swallowing of air in 20 healthy volunteers before and after a meal. Radiography was used to measure the size of the intragastric air bubble. Gastro-oesophageal reflux was assessed by concurrent impedance and pH measurement. RESULTS: The rate of air swallowing was correlated to the size of the intragastric air bubble postprandially and to the rate of gaseous gastro-oesophageal reflux. The number of air swallows and the size of the intragastric air bubble did not correlate with the number of liquid acid and non-acid reflux episodes. CONCLUSIONS: In healthy subjects, air swallowing promotes belching but does not facilitate acid reflux.     

Correlation between gastric pH and gastro-oesophageal reflux contents: ambulatory pH-impedance monitoring results

Gastro-oesophageal reflux events should be related to gastric contents. The goal of this study was to determine the relationship between gastric pH and the nature of reflux events. Ambulatory oesophageal pH-impedance and gastric pH monitoring was performed in 41 patients [29 off and 12 on proton pump inhibitor (PPI) therapy] and 12 controls. The mean gastric pH was measured within 2 min around the reflux episodes, 10 cm below the cardia. Acid reflux events occurred more frequently at gastric pH <4 (89%) than non-acid reflux events (63%, P < 0.0001). Acid reflux events extended more frequently 15 cm above the lower oesophageal sphincter (LOS; 34%) than non-acid reflux episodes (24%, P = 0.005). Gastric pH was significantly lower during interprandial reflux events than during postprandial ones in the three groups (P < 0.001). A positive correlation was found between gastric pH and the nadir oesophageal pH during reflux events in the three groups: this correlation was more significant in patients on PPI therapy. We conclude that most acid and non-acid reflux episodes occur at acid gastric pH, as measured 10 cm below the LOS. This measure does not appear a good predictor of the pH of reflux events.     

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.     

Mechanisms underlying duodeno-gastric reflux in man

BACKGROUND: Recent studies suggest that duodeno-gastro-oesophageal reflux (DGER) contributes to the occurrence of reflux oesophagitis and Barrett's oesophagus. The mechanisms underlying duodeno-gastric reflux (DGR), a prerequisite for DGER, are poorly understood. AIMS: To study the occurrence of DGR in relation to interdigestive and postprandial gastroduodenal motility. SUBJECTS AND METHODS: Ten healthy subjects underwent stationary gastroduodenal manometry with simultaneous duodenal and antral Bilitec recording 4 h before and 5 h after ingestion of a liquid meal. Eight volunteers underwent the same study, with administration of erythromycin postprandially. RESULTS: During the interdigestive phase II, all volunteers had short DGR episodes. Postprandially, DGR occurred in all subjects, on average 39 +/- 28 min after the start of the meal, and was cleared from the stomach after 242 +/- 23 min. Induction of increased antral motility and of a premature phase III, by administration of erythromycin, was associated with faster gastric DGR clearance. However, there was no direct temporal relationship between erythromycin-induced gastric phase III and erythromycin-induced DGR clearance. CONCLUSION: In healthy subjects, duodenogastric reflux occurs sporadically in the interdigestive state and is a normal phenomenon in the postprandial period. Erythromycin induces faster clearance of DGR from the stomach, which depends on enhanced antral contractile activity rather than premature phase III.     

Mechanisms of gastroesophageal reflux in children with sequelae of birth asphyxia

Patterns of childhood gastroesophageal reflux (GER) have been studied extensively; however, the mechanisms underlying its occurrence in neurologically impaired children (NIC) are poorly understood. Concurrent esophageal manometry and pH monitoring was conducted in 10 un-operated children (7 male; mean age: 59.5 months) with sequelae birth asphyxia and esophagitis. Reflux episodes were scored when esophageal pH decreased to <4 for at least 5s. When the rate of decrease of lower esophageal sphincter (LES) pressure was >1mmHg/s, the decrease of LES pressure was defined as LES relaxation. The time relationship of the pharyngeal manometric swallowing signal to LES relaxation onset was then evaluated in order to distinguish between LES relaxations associated with swallowing (type II or III, associated with one or more swallows, respectively) and those that occurred independently of swallowing (type I). Results: Esophageal manometry and pH monitoring were conducted for a mean duration of 91.5min. Basal LES pressure averaged (+/-SD) 9.2+/-4.8mmHg; in 4 of 10 patients (40%) the LES pressure was largely undetectable, varying between 0 and 2mmHg. Mean LES pressure was inversely correlated with age (r=0.7, P=0.02). The total number of reflux episodes/h averaged 32.1+/-12.1 LES pressure reached 0mmHg in 98% of reflux episodes. Type I LES relaxations were present in 3.15+/-1.1 reflux episodes/h, whereas type II LES relaxation occurred in 2.3+/-2.4 episodes/h. Acid reflux episodes appeared during absent basal LES tone periods, without phasic LES relaxations, in 74%. Conclusions: Absent basal LES tone is the main mechanism of GER in a subgroup of NIC, especially in older children. Transient LES relaxation, the most common known event associated with acid reflux in neurologically normal children, seems to precede a minority of reflux events in NIC.     

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.