Studies of the oesophageal clearance responses to intraluminal acid

Influence of Acid Swallows on the Dynamics of the Upper Esophageal Sphincter

Mechanisms of the upper esophageal sphincter (UES) when exposed to acid are still incompletely understood. The presented work investigated the reaction of the UES to acid exposure during swallowing. Ten healthy individuals swallowed ten 2 ml neutral water boli of pH 7, followed by 10 swallows each of different levels of acidity (pH 1.8, pH 3 and pH 5). Effects were analyzed by high-resolution manometry (HRM) for the primary parameter Restitution Time, as well as Resting Pressures, maximal, minimal pressures and time intervals. Restitution Times measured mean values of 12.67 s (SD ± 7.03 s) for pH 1.8, pH 7 = 8.69 s (SD ± 2.72 s), pH 3 = 7.56 s (SD ± 2.23 s) and pH 5 = 7.29 s (SD ± 2.55 s), showing prolonged Restitution Times in the UES when exposed to strong bolus acidity. This difference was significant towards the neutral bolus, but also to less acidic boli (pH 5: p = 0.006, pH 3: p = 0.009, pH 7: p = 0.038). Considerable differences of mean values were found for Post-Swallow Maximum and Period of Sphincter Activity. Also, Pre-Swallow Maximum values were found to be highest with the strongest acid. Relaxation Times showed a slight trend of prolongation for the highest bolus acidity. Prolonged Restitution Times may represent a reflexive protective mechanism triggered by receptors in the pharyngeal mucosa or the UES preventing regurgitation of acid into the pharynx and larynx, besides representing ongoing attempts of acid clearance. Exposure to high levels of acidity by a swallowed bolus does influence UES functions during swallowing.

Gamma-aminobutyric acid receptor type B agonist baclofen inhibits acid-induced excitation of secondary peristalsis but not heartburn sensation

BACKGROUND AND AIM

Acute esophageal acid infusion promotes distension-induced secondary peristalsis. The gamma-aminobutyric acid receptor type B (GABA-B) receptors activation inhibits secondary peristalsis. This study aimed to test the hypothesis whether acid excitation of secondary peristalsis can be influenced by baclofen.

METHODS

Secondary peristalsis was performed with intra-esophageal slow and rapid air injections in 13 healthy subjects. Direct esophageal infusion of 0.1 N HCl following pretreatment with placebo or baclofen was randomly performed at least 1 week apart. Symptom intensity, distension thresholds, and peristaltic parameters were determined and compared between each study protocol.

RESULTS

The intensity of heartburn symptom in response to esophageal acid infusion was significantly greater with baclofen than the placebo (P = 0.002). The threshold volume of secondary peristalsis during slow air injections in response to acid infusion was significantly greater with baclofen than the placebo (P = 0.001). Baclofen significantly increased the threshold volume of secondary peristalsis during rapid air injections in response to acid infusion (P = 0.001). The frequency of secondary peristalsis in response to acid infusion was significantly decreased by baclofen as compared with the placebo (P = 0.001). Baclofen significantly decreased peristaltic amplitudes in response to acid infusion during rapid air injections (P = 0.007).

CONCLUSIONS

Gamma-aminobutyric acid receptor type B agonist baclofen inhibits acid excitation of secondary peristalsis in human esophagus, which is probably mediated by both muscular and mucosal mechanoreceptors. This work supports the evidence of potential involvement of GABA-B receptors in negative modulation of acid excitation of esophageal perception as well as secondary peristalsis.

Influence of intraluminal acidification on esophageal secondary peristalsis in humans

BACKGROUND

Secondary peristalsis contributes to clearance of retained refluxate or material from the esophagus.

AIM

The goal of our study was to investigate the effects of hydrochloric acid (HCl) on physiological characteristics of esophageal secondary peristalsis in healthy adults.

METHODS

After recording esophageal motility baseline for primary peristalsis, secondary peristalsis was stimulated with slow and rapid air injections in the mid-esophageal in 16 healthy subjects. Normal saline and HCl (0.1 N) were separately infused into the esophagus to test whether they had effects on secondary peristalsis.

RESULTS

After infusion of HCl, the threshold volume to generate secondary peristalsis was significantly decreased during rapid and slow air infusions (both P < 0.05). The frequency of secondary peristalsis was increased after HCl infusion (90 % [72.5-100 %] versus 85 % [72.5-90 %], P = 0.002). Infusion of HCl significantly increased pressure wave amplitude during rapid and slow air infusions (both P < 0.05). Infusion of saline did not affect any parameters of secondary peristalsis. The occurrence of heartburn was generated in 7 of 16 subjects after infusion of HCl with an increase in visual analogue scale score (12.5).

CONCLUSIONS

Our data show that acute esophageal acid infusion enhances sensitivity of distension-induced secondary peristalsis and enhances secondary peristaltic activity. The study supports the evidence of the presence of acid-sensitive afferents in the modulation of distension-induced secondary peristalsis in humans.

Response of cricopharyngeus muscle to esophageal stimulation by mechanical distension and acid and bile perfusion

OBJECTIVES

The aim of this study was to identify the response of the cricopharyngeus muscle (CPM) to esophageal stimulation by intraluminal mechanical distension and intraluminal acid and bile perfusion.

METHODS

In 3 adult pigs, electromyographic (EMG) activity of the CPM was recorded at baseline and after esophageal stimulation at 3 levels: proximal, middle, and distal. The esophagus was stimulated with 20-mL balloon distension and intraluminal perfusion of 40 mL 0.1N hydrochloric acid, taurocholic acid (pH 1.5), and chenodeoxycholic acid (pH 7.4) at the rate of 40 mL/min. The EMG spike density was defined as peak-to-peak spikes greater than 10 microV averaged over 10-ms intervals.

RESULTS

In all 3 animals, the spike density at baseline was 0. The spike densities increased after proximal and middle distensions to 15.2 +/- 1.5 and 5.1 +/- 1.2 spikes per 10 ms, respectively. No change in CPM EMG activity occurred after distal distension. The spike density following intraluminal perfusion with hydrochloric acid at the distal level was 10.1 +/- 1.1 spikes per 10 ms. No significant change in CPM EMG activity occurred after acid perfusion at the middle and proximal levels. No change in CPM EMG activity occurred after intraluminal esophageal perfusion with either taurocholic acid or chenodeoxycholic acid.

CONCLUSIONS

Proximal esophageal distension, as well as distal intraluminal acid perfusion, appeared to be important mechanisms in generation of CPM activity. Bile acids, on the other hand, failed to evoke such CPM activity. The data suggest that transpyloric refluxate may not be significant enough to evoke the CPM protective sphincteric function, thereby placing supraesophageal structures at risk of bile injury.

The refluxate: The impact of its magnitude, composition and distribution

The pathogenesis of gastrointestinal reflux disease is multifactoral. Integral to the disease process is the refluxate itself. The characteristics and composition of the refluxate are dependent on several physiological variables. The refluxate may contain varying concentrations of acid, pepsin, gas, or contents of duodenal reflux (such as bile acid and pancreatic enzymes). Characteristics such as volume and proximal extent of the refluxate, and the chemical content of this refluxate can strongly influence the risk of symptom perception. Strong acid (pH<4) and duodeno-gastro-oesophageal reflux are also implicated in the development of mucosal damage in the form of oesophagitis, Barrett's metaplasia and oesophageal adenocarcinoma. The manifestation of disease, however, is not entirely reliant on the refluxate, which must be considered in the context of the genetic, environmental and psychological susceptibility of the individual.

Modulation of activity in swallowing motor cortex following esophageal acidification: a functional magnetic resonance imaging study

Esophageal acid exposure induces sensory and motility changes in the upper gastrointestinal tract; however, the mechanisms involved and the effects on activity in the brain regions that control swallowing are unknown. The aim of this study was to examine functional changes in the cortical swallowing network as a result of esophageal acidification using functional magnetic resonance imaging (fMRI). Seven healthy volunteers (3 female, age range=20-30 years) were randomized to receive either a 0.1 M hydrochloric acid or (control) saline infusion for 30 min into the distal esophagus. Postinfusion, subjects underwent four 8 min blocks of fMRI over 1 h. These alternated between 1 min swallowing water boluses and 1 min rest. Three-dimensional cluster analysis for group brain activation during swallowing was performed together with repeated-measures ANOVA for differences between acid and saline. After acid infusion, swallowing-induced activation was seen predominantly in postcentral gyrus (p<0.004). ANOVA comparison of acid with saline showed a significant relative reduction in activation during swallowing of the precentral gyrus (M1) BA 4 (p<0.008) in response to acid infusion. No areas of increased cortical activation were identified with acid vs. saline during swallowing. Esophageal acidification inhibits motor and association cortical areas during a swallowing task, probably via changes in vagal afferent or nociceptive input from the esophagus. This mechanism may play a protective role, facilitating acid clearance by reduced descending central motor inhibition of enteric/spinal reflexes, or by preventing further ingestion of injurious agents.

Manometric study of the lower esophageal sphincter and esophagus in subtotal gastrectomy patients

There is controversy in the literature regarding the motor function behavior of the lower esophageal sphincter and esophagus following partial gastrectomy. We studied 26 patients with gastric adenocarcinoma of the distal corpus and/or antrum who underwent radical subtotal gastrectomy with Roux-en-Y reconstruction. There were 15 women (57.69%) and 11 men (42.31%) with a mean age of 57.2 years; 21 were White (80.8%) and five were of African descent (19.2%). Before the surgery and 3 months afterwards, every patient underwent manometric and endoscopic examinations. The lower esophageal sphincter showed reductions in mean respiratory pressure (19.41-15.59 mmHg, P= 0.02) and maximum expiratory pressure (8.13-5.54 mmHg, P= 0.02) without significant alteration in diaphragmatic crura pressure (32.92-30.64 mmHg, P= 0.37). An increase in peristaltic wave amplitude (91.43-124.86 mmHg, P < 0.01) and peristaltic wave conduction velocity (3.29 cm/s to 4.23 cm/s; P= 0.024) were detected in esophageal function. The presence of erosive esophagitis decreased from 10 (38.46%) patients to none (P= 0.002). We concluded that following surgery the lower esophageal sphincter function was impaired, through decreased pressure in the esophageal component without alteration in diaphragmatic crura pressure. On the other hand, there was significant increase in peristaltic wave amplitude and velocity, and improvement of the erosive esophagitis. The authors suggest that subtotal gastrectomy, with gastroesophageal junction preservation, and Roux-en-Y reconstruction should be the preferred operation for distal gastric cancer to minimize esophageal dysfunction and gastroesophageal reflux disease.

Differential relaxation and contractile responses of the human upper esophageal sphincter mediated by interplay of mucosal and deep mechanoreceptor activation

the neural mechanisms of distension-induced esophagoupper esophageal sphincter (UES) reflexes have not been explored in humans. We investigated the modulation of these reflexes by mucosal anesthesia, acid exposure, and GABA(B) receptor activation. In 55 healthy human subjects, UES responses to rapid esophageal air insufflation and slow balloon distension were examined before and after pretreatment with 15 ml of topical esophageal lidocaine, esophageal HCl infusion, and baclofen 40 mg given orally. In response to rapid esophageal distension, UES can variably relax or contract. Following a mucosal blockade by topical lidocaine, the likelihood of a UES relaxation response was reduced by 11% (P < 0.01) and the likelihood of a UES contractile response was increased by 14% (P < 0.001) without alteration in the overall UES response rate. The UES contractile response to rapid esophageal air insufflation was also increased by 8% (P < 0.05) following sensitization by prior mucosal acid exposure. The UES contractile response, elicited by balloon distension, was regionally dependent (P < 0.05) (more frequent and of higher amplitude with proximal esophageal distension), and the response was attenuated by topical lidocaine (P < 0.05). Baclofen (40 mg po) had no effect on these UES reflexes. Abrupt gaseous esophageal distension activates simultaneously both excitatory and inhibitory pathways to the UES. Partial blockade of the mucosal mechanosensitive receptors permits an enhanced UES contractile response mediated by deeper esophageal mechanoreceptors. Activation of acid-sensitive esophageal mucosal chemoreceptors upregulates the UES contractile response, suggestive of a protective mechanism.

Relevance of volume and proximal extent of reflux in gastro-oesophageal reflux disease

In patients with gastro-oesophageal reflux disease (GORD), oesophageal and extraoesophageal symptoms are traditionally attributed to increased contact time between the mucosa and refluxates. However, the volume of reflux may be important by increasing the total amount of highly concentrated damaging substances, either by prolonging distal mucosal exposure or by expanding to more proximal areas. To date, it has not been possible to accurately measure the volume of gastro-oesophageal reflux. Determination of the volume of reflux will help to better understand the pathophysiology of GORD and to evaluate the efficacy of antireflux treatments.

Esophageal Acid clearance: more volume-dependent than motility-dependent in healthy piglets

BACKGROUND/AIMS

The present study investigates manometrically in healthy piglets whether esophageal clearance after distension with different volumes of acid is volume-dependent.

METHODS

Sedated, non-intubated piglets (n = 22) underwent stationary manometry of the esophagus with a 4-probe perfused assembly after successive injection of 1, 2, and 3 mL of saline and acid. Simultaneous pH metering allowed assessment of acid clearance. Wave features and clearance times after saline and acid were compared by paired non-parametric tests and Friedman analysis of variance. The linearity of the relationships between the clearance times and the volumes of acid infused were tested after square root transformations by one-way ANOVA repeated measures. The significance level was set at < 0.05.

RESULTS

The motor response was identical after distension with saline and acid except for the largest amount of acid used, which elicited more waves during the first 5 minutes after infusion. Time elapsed until regaining pH4 was longer after higher amounts of acid, but not significantly, whereas that necessary to regain baseline pH was significantly longer after such challenge. Esophageal motility was practically identical after 1 and 2 mL of acid, but it was slightly less effective in the first minute after the 3 mL challenge. There was a linear correlation between clearance times and volumes of acid infused.

CONCLUSIONS

Up to a certain volume, the motor responses of the healthy esophagus to distension with neutral or acid fluids were similar. Acid clearance was more a function of the amount of acid present than of the motor response elicited by its presence. Only when the amount of acid was large, esophageal motor response was worse than that elicited after equivalent volumes of neutral fluid. The present evidence suggests that long episodes of reflux in pH tracings might reflect large volumes of refluxate as well as disturbed motor function.

Manometric characteristics of the upper esophageal sphincter recorded with a microsleeve

OBJECTIVES

We compared manometric recordings of the upper esophageal sphincter (UES) recorded with a miniature sleeve to those obtained using standard manometry.

METHODS

The UES pressure of eight volunteer subjects was measured by station pull-through (SPT), by rapid pull-through (RPT), and with a microsleeve sensor for 30 min, followed by 15 min of esophageal acid infusion. Deglutitive UES relaxation recorded with a microsleeve and solid state sensor were compared.

RESULTS

The UES pressure recorded with the microsleeve (25+/-9 mm Hg) was significantly less than that by SPT (114+/-18 mm Hg) or RPT (152+/-19 mm Hg), and was unaffected by acid infusion. Periods of low UES pressure were observed during long interswallow intervals (11+/-4, range 6-18 mm Hg). Deglutitive relaxation duration and intrabolus pressure measured with the microsleeve were less than those recorded by the solid state transducer.

CONCLUSIONS

"Normal" UES pressure is heavily dependent on measurement technique; pressures obtained with a miniature sleeve are a fraction of those obtained by SPT or RPT. During periods of relative comfort with minimal swallowing, UES tone is approximately 10 mm Hg, similar to that during sleep. Volume modulation of deglutitive UES relaxation is demonstrable with a microsleeve, albeit with less precision than with a solid-state transducer.

Esophageal body motor response to reflux events: secondary peristalsis

The esophageal body is a major component of the antireflux mechanism. Disruption of esophageal peristalsis affects both volume clearance and delivery of swallowed saliva to the distal esophageal body. The esophageal body responds to reflux by an increase in primary peristalsis through stimulation of swallowing and secondary peristalsis through esophageal distension. Primary peristalsis is the most common motor event after reflux and accounts for up to 90% of initial and subsequent motor activity. Secondary peristalsis is uncommon but may be important during sleep when swallowing is relatively suppressed. Some patients with reflux disease, particularly those with severe esophagitis, exhibit impaired esophageal responses to reflux. It is likely that this impairment prolongs acid clearance and may also influence the proximal extent of the refluxate within the esophageal body.

Oesophageal motor responses to gastro-oesophageal reflux in healthy controls and reflux patients

AIMS

To compare oesophageal motor responses to gastro-oesophageal reflux (GOR) in 16 healthy controls (group 1) and 25 reflux patients, 15 without (group 2) and 10 with (group 3) oesophagitis.

METHODS

All subjects underwent 24 hour ambulatory oesophageal pH measurements (5 cm above the lower oesophageal sphincter (LOS)) combined with pressure monitoring (5, 10, and 15 cm above the LOS for oesophageal body motility and 27 cm above the LOS for voluntary swallow detection). Contraction patterns (peristaltic, simultaneous, isolated, mixed type, and non-transmitted swallows) and peristaltic contraction wave characteristics (amplitude, duration, and velocity) during GOR were compared in the three groups.

RESULTS

The average number of motor activities per minute was significantly higher in group 1 (p < 0.05). In all groups, the most common motor contraction pattern was peristaltic. The percentage of peristaltic activity per subject was significantly higher in group 1 (p < 0.05). There were no significant differences in other contraction patterns among the three groups (p > 0.05). Of the peristaltic contraction wave characteristics there were no significant differences in any parameters (amplitude, duration, and velocity) among the three groups (p > 0.05). The average pH increment in response to motor activities was significantly higher in group 1 (p < 0.05).

CONCLUSIONS

Motor responses to GOR were found to be predominantly primary peristaltic in all groups. During GOR, reflux patients have less frequent activity, a smaller proportion of activity is peristaltic, and the average pH increment in response to motor activities is reduced compared with controls.

Methodological factors affecting esophageal clearance

To define some methodological factors that could affect the measurement of the esophageal clearance, we used three different protocols, on 41 healthy control subjects. In 20 subjects, we studied the influence of a naso-esophageal probe on the frequency of swallowing. We observed a significant (44 +/- 5%) decrease in the frequency of spontaneous swallows after 15 minutes, with stabilization after this 15 minute period of adaptation. In 11 subjects, we studied the influence of the pH of the esophageal content on esophageal clearance. We found an exponential relationship between the esophageal clearance (C) expressed in minutes and the initial pH of the lumen contents: C = 43.3 exp (-0.54 pH) In 10 other subjects, we studied the influence of the volume of the esophageal contents on esophageal clearance. We found no influence for volumes less than 30 ml and a significant increase of clearance for volumes greater than 30 ml. In summary, this study of the effects of methodological factors on esophageal clearance: Gives new information about the "accommodation phase" of the esophagus after distension by a naso-gastric probe; Allows us to propose a new quantitative method for evaluation of esophageal clearance Shows the small importance of the ingested volume.

Review article: factors protecting the oesophagus against acid-mediated injury

Reflux of gastric acid and pepsins into the lower oesophagus causes symptoms such as heartburn and nausea, and tissue injury leading to erosive oesophagitis and stricture formation. This article reviews the mechanisms involved in protecting the oesophagus against acid-mediated injury, including the role of the lower oesophageal sphincter, secondary oesophageal peristalsis and swallowed saliva. The oesophageal mucosa has inherent abilities to resist acid damage, and recent data from three laboratories suggest a secretory function with local production of bicarbonate and mucus responsive to local acidification. The evidence for these putative oesophageal defence mechanisms is discussed.

Effect of topical oesophageal acidification on human salivary and oesophageal alkali secretion

Recent human studies suggest that oesophageal HCO3- secretion, in conjunction with salivary HCO3- secretion and secondary oesophageal peristalsis, is important for the protection of oesophageal mucosa from refluxed gastric contents. This study evaluated simultaneously the responsiveness of oesophageal and salivary HCO3- secretion to oesophageal acidification in eight healthy subjects. A 10 cm segment of oesophagus was perfused at a constant rate of 5 ml/min with a specially designed tube assembly. Saline was used initially, and then 10 mM and 100 mM HCl. The perfusates contained 3H-polyethylene glycol (PEG) as a concentration marker to determine volumes. Corrections were applied for a small degree of contamination by swallowed saliva and refluxed gastric alkali. Oesophageal perfusion with 10 mM HCl did not cause symptoms (nausea and heartburn), but tripled the oesophageal HCO3- output from a baseline of 51 mumol/10 cm/10 min (p = 0.021), while doubling the rate of salivary HCO3- secretion from a median basal value of 140 mumol/10 min (p = 0.021). Oesophageal perfusion with 100 mM HCl was associated with symptoms of nausea and heartburn in all subjects. The median oesophageal HCO3- output increased 32 fold to 1659 mumol/10 cm/10 min (interquartile range 569 to 3373; p = 0.036), and salivary HCO3- secretion approximately tripled from basal values (p = 0.036). In conclusion, oesophageal acidification stimulates both salivary and oesophageal HCO3- secretion, responses which may be protective to the oesophageal epithelium.

Stimulation and characteristics of secondary oesophageal peristalsis in normal subjects

The study evaluates the triggering and characteristics of secondary oesophageal peristalsis in 25 healthy volunteers. Secondary peristalsis was stimulated by rapid intraoesophageal injection of boluses of air and water, and by a five second oesophageal distension with a balloon. Air and water boluses triggered secondary peristalsis that started in the proximal oesophagus regardless of injection site. Response rates were volume dependent with 83% of the 20 ml air boluses triggering secondary peristalsis compared with 2% for the 2 ml water bolus (p < 0.0001). Response rates for air and water were similar for equal bolus volumes and were not influenced by the site of injection. In contrast, balloon distension usually induced a synchronous contraction above the balloon, with secondary peristalsis starting below the balloon after deflation. The peristaltic response rate to balloon distension was also volume dependent and the middle balloon was more effective in triggering secondary peristalsis than either the upper or lower balloons (p < 0.001). Secondary peristaltic amplitude was less than that of primary peristalsis (p < 0.001). Secondary peristaltic velocity with a water bolus was slower (p = 0.001) than that of primary peristalsis. Intravenous atropine significantly reduced secondary peristaltic responses to all stimuli. There was also a significant reduction in pressure wave amplitude for air stimulated secondary peristalsis while those for the water responses were similar. Secondary peristaltic velocity with air and water boluses was not changed by atropine. The reproducibility of testing secondary peristalsis was examined six volunteers and did not show any significant differences on separate test days in response rate and peristaltic amplitude or velocity. It is concluded that in normal subjects, secondary peristalsis can be more reliably triggered by intraoesophageal air or water infusion than balloon distension. Secondary peristaltic amplitude and velocity are stimulus but not site or volume dependent and propagation is partially mediated by cholinergic nerves.

Measurement of bicarbonate output from the intact human oesophagus

Injury of the oesophageal mucosa can result from exposure to refluxed gastric acid and pepsin. Competence of the lower oesophageal sphincter and peristaltic activity serve to reduce contract time between luminal acid and oesophageal mucosa, but intraluminal neutralisation of residual acid by bicarbonate may also be important in preventing oesophageal mucosal injury. Whereas swallowed saliva contains bicarbonate, recent experiments have also demonstrated alkali secretion from the mammalian oesophagus. Bicarbonate secretion from the human oesophagus was therefore examined with an intubation technique and perfusion of the oesophagus with a non-absorbable marker. Saliva, gastric, and oesophageal aspirates were collected and bicarbonate concentrations determined by measurements of pH and pCO2 or by back titration. In 32 normal subjects (17 women, 15 men) median basal oesophageal bicarbonate secretion determined by a pH/pCO2 method was 416 (range 139-1050) mumol/hour/10 cm. In a subgroup of 15 experiments median oesophageal bicarbonate output was 489 (range 157-1033) mumol/hour/10 cm (pH/pCO2 method) compared with a median alkali output of 563 (range 135-799) mumol/hour/10 cm as determined by back titration. The difference was not significant. Salivary contamination of the oesophagus accounted for 25% of all bicarbonate measured within the oesophagus and refluxed gastric bicarbonate accounted for 2.5%. Bicarbonate secretion from the normal human oesophagus may, in combination with swallowed salivary bicarbonate, play a part in preventing oesophageal mucosal damage due to refluxed gastric acid and pepsin.

Chronic persistent cough and clearance of esophageal acid

Unexplained chronic persistent cough has been shown to be associated with increased episodes of otherwise asymptomatic gastroesophageal reflux; however, normal subjects without cough also exhibit some reflux. We postulate that the prompt clearance of refluxed acid from the esophagus may play an important role in the prevention of cough, and we sought to determine if patients with chronic cough have impaired clearance. Thirty patients with unexplained chronic cough underwent 24-h ambulatory esophageal pH monitoring. Compared to 12 matched control subjects, patients experienced significantly more episodes (all values expressed as median [range]) of reflux per 24 h (88.3 [5.0 to 338.0] vs 5.7 [0 to 13.0]; p < 0.0001) and had impaired clearance of esophageal acid as measured by the duration of individual reflux episodes (3.0 [0.1 to 20.5] min per reflux vs 0.7 [0 to 2.5] min per reflux; p < 0.01). We conclude that patients with chronic persistent cough have impaired clearance of esophageal acid.

A wave of inhibition precedes primary peristaltic contractions in the human esophagus

Animal studies have shown that primary esophageal peristalsis is preceded by a wave of inhibition spreading rapidly down the esophagus and lasting longer in more distal segments. In humans, its presence in the esophageal body cannot be demonstrated manometrically because of the absence of tone. To study deglutitive inhibition in humans, an artificial high-pressure zone was created by inflating an intraesophageal balloon to a critical level. The pressure changes at the interface between the balloon and the esophageal wall at various levels along the esophagus were measured. In this artificial high-pressure zone, deglutition induced a relaxation beginning simultaneously at various levels of the esophagus but lasting progressively longer in progressively more distal segments. Latency from onset of deglutition to onset of relaxation at 13 cm and 8 cm above the lower esophageal sphincter and at the lower esophageal sphincter was 0.06 +/- 0.19 seconds, 0.10 +/- 0.31 seconds, and 0.89 +/- 0.53 seconds, respectively; latency to contraction was 4.45 +/- 0.54 seconds, 6.04 +/- 0.79 seconds, and 9.14 +/- 1.04 seconds, respectively. This is the first direct evidence that deglutition produces in the human esophagus a wave of inhibition that precedes the primary peristaltic contraction.

Interaction of gastroesophageal reflux and esophageal motility. Evaluation by ambulatory 24-hour manometry and pH-metry

The present study addresses the question of whether esophageal motility shortly before, during, and after gastroesophageal reflux (GER) is different in patients with GER disease and healthy controls. Twenty-four-hour continuous recordings of intraesophageal pressures and pH were performed in 12 unselected patients with clinically proven GER disease and in 11 volunteers using a new ambulatory and digital recording device. All GER episodes in each studied subject were classified according to their associated motility pattern shortly before (induction period) and during (response period) GER. More GER episodes were analyzed in patients than in volunteers (median: 41 vs 26, P less than 0.05), and a total of 917 GER episodes (593 in patients, 324 in volunteers) was recorded. During the induction period patients more often had irregular esophageal contractions (median: 23% vs 13%, P less than 0.05) and less often had a peristaltic sequence (median: 6% vs 21%) than normals. No difference between patients and controls existed when comparing the frequency of negative pressure peaks or common cavity phenomena shortly before GER. During the response period peristaltic motility in patients was decreased (median: 10% vs 47%, P less than 0.05). We conclude that: (1) GER events in GER patients are more often associated with irregular esophageal contractions than in healthy controls; (2) GER patients present with a diminished, if any, esophageal peristalsis during GER; and (3) combined ambulatory manometry and pH-metry provides clinically useful information on the individual pathogenesis of GER disease, which is superior to the information retrieved by pH-metry alone.