The effects of an inhaled beta(2)-adrenergic agonist on lower esophageal function: a dose-response study

Gastroesophageal reflux in mechanically ventilated pediatric patients and its relation to ventilator-associated pneumonia

INTRODUCTION

The objective was to determine the frequency of gastroesophageal reflux (GER) in mechanically ventilated pediatric patients and its role as a risk factor for ventilator-associated pneumonia (VAP), which may be enhanced among those patients.

METHODS

The study is a prospective cohort study of mechanically ventilated pediatric patients in the pediatric intensive care unit (PICU) of Ain Shams University Children's Hospital. It was conducted in 24 mechanically ventilated patients (16 of them developed VAP and 8 did not, with mean age of 16.6 +/- 20.5 and 18.6 +/- 22.4 months respectively). Esophageal 24-hour pH-metry beside clinical and laboratory evaluation of their underlying problem and severity of their condition were carried out.

RESULTS

All VAP patients had GER (50% alkaline reflux, 12.5% acidic reflux and 37.5% combined reflux) compared to 75% of non-VAP ones (100% alkaline reflux). The mean total reflux time was significantly longer among VAP (50 minutes) versus non-VAP (3 minutes) patients. There was significant increase in acidic reflux parameters among non-survivors versus survivors (P < 0.001). For VAP mortality, total acidic reflux at a cut-off value of 28.6 minutes is found to be a mortality predictor with a sensitivity of 100% and a specificity of 100%.

CONCLUSIONS

GER is a constant incident in mechanically ventilated pediatric patients, with alkaline reflux being more common than acidic reflux. Both acidic and alkaline refluxes were found to be associated with the development of VAP and total reflux time was found to be a reliable predictor of VAP. Moreover, acidic reflux was found to be more related to mortality than alkaline reflux.

Incidence and treatment results of laryngopharyngeal reflux in chronic obstructive pulmonary disease

Laryngopharyngeal reflux (LPR) is defined as the movement of gastric content towards the larynx and the pharynx and it may cause respiratory symptoms or difficulty in their control. We aimed to find the frequency of LPR in chronic obstructive pulmonary disease (COPD) patients and to investigate its effect on COPD symptoms and the results of its treatment. At baseline 30 (20 male, 10 female, mean age: 65 +/- 10 years) COPD patients completed LPR and COPD symptom questionnaires and 13 (44%) were diagnosed with LPR based on laryngeal examination. Patients with LPR were given 2 months of PPI treatment, after which LPR and COPD symptom questionnaires, laryngeal examinations and pulmonary function tests were repeated. Following the treatment, significant improvements in COPD symptom index, LPR symptom index and laryngeal examination findings were observed in patients with LPR (P < 0.01, P < 0.01, P < 0.0001, respectively). Treatment of LPR resulted in a significant improvement in the symptoms of COPD.

The effects of nebulized albuterol on esophageal function in asthmatic patients

PURPOSE

Albuterol reduces lower esophageal sphincter (LES) pressure in normal volunteers, although the effects of albuterol on esophageal function in asthmatic patients are not known. The aim of this study was to evaluate the effects of nebulized albuterol on lower esophageal function in asthmatic patients. Symptoms and a methacholine challenge test were used to identify asthmatic patients who were then enrolled in a prospective, randomized, placebo-controlled, double-blinded, crossover trial. Changes in esophageal function in response to nebulized albuterol or placebo were evaluated over two sessions spaced 1 week apart.

RESULTS

Albuterol induced a dose-dependent drop in lower esophageal sphincter basal pressure with a threshold dose as low as 2.5 mg. Albuterol did not affect the amplitude of esophageal contractions.

CONCLUSIONS

Nebulized albuterol induces a dose-dependent reduction in LES basal pressure in asthmatic patients. These effects raise the possibility that gastroesophageal reflux may occur after bronchodilator therapy.

Review article: respiratory manifestations of gastro-oesophageal reflux disease

BACKGROUND

Respiratory manifestations represent one of the most prevalent and difficult-to-manage extra-oesophageal syndromes of gastro-oesophageal reflux disease.

AIMS

To review the epidemiology, pathophysiological mechanisms and therapeutic outcomes of reflux-related respiratory disorders.

METHODS

Search of the literature published in English using PubMed database.

RESULTS

There is a discrepancy between the high prevalence of reflux in asthmatics and the limited efficacy of antireflux therapies. Asthma per se may cause reflux. Patients with difficult-to-treat asthma and/or nocturnal symptoms should be screened for reflux. Reflux can induce chronic cough through different mechanisms including micro-aspiration and both local and central reflexes. Cough and reflux may precipitate each other. A meta-analysis found no significant difference between placebo and proton pump inhibitors in the resolution of cough. Encouraging results have been reported, following antireflux surgery in patients selected on the basis of pH-impedance monitoring. Attention has been drawn to obstructive sleep apnoea syndrome.

CONCLUSIONS

The role of gastro-oesophageal reflux disease in the pathogenesis of miscellaneous respiratory disorders has been discussed for decades and established in asthma and cough. However, no major therapeutic advances have been reported recently. Future trials should concentrate on patient selection and the control of efficacy using recently developed technologies, such as pH-impedance monitoring.

Environmental factors in the etiology of gastroesophageal reflux disease

Gastroesophageal reflux disease (GERD) is currently one of the most common health problems in the Western world, affecting up to 20% of the adult population weekly and 50% monthly. It generates substantial suffering among patients as well as significant costs to both patients and society in general. GERD can further result in serious complications such as esophageal strictures, Barrett's esophagus and esophageal adenocarcinoma. This review discusses the current knowledge on risk factors and potential protective factors in the development of GERD.

Regulation of basal tone, relaxation and contraction of the lower oesophageal sphincter. Relevance to drug discovery for oesophageal disorders

The lower oesophageal sphincter (LOS) is a specialized region of the oesophageal circular smooth muscle that allows the passage of a swallowed bolus to the stomach and prevents the reflux of gastric contents into the oesophagus. The anatomical arrangement of the LOS includes semicircular clasp fibres adjacent to the lesser gastric curvature and sling fibres following the greater gastric curvature. Such anatomical arrangement together with an asymmetric intrinsic innervation and distinct proportion of neurotransmitters in both regions produces an asymmetric pressure profile. The LOS tone is myogenic in origin and depends on smooth muscle properties that lead to opening of L-type Ca(2+) channels; however it can be modulated by enteric motor neurons, the parasympathetic and sympathetic extrinsic nervous system and several neurohumoral substances. Nitric oxide synthesized by neuronal NOS is the main inhibitory neurotransmitter involved in LOS relaxation. Different putative neurotransmitters have been proposed to play a role together with NO. So far, only ATP or related purines have shown to be co-transmitters with NO. Acetylcholine and tachykinins are involved in the LOS contraction acting through acetylcholine M(3) and tachykinin NK(2) receptors. Nitric oxide can also be involved in the regulation of LOS contraction. The understanding of the mechanisms that originate and modulate LOS tone, relaxation and contraction and the characterization of neurotransmitters and receptors involved in LOS function are important to develop new pharmacological tools to treat primary oesophageal motor disorders and gastro-oesophageal reflux disease.

Extraesophageal manifestations of gastroesophageal reflux disease

Gastroesophageal reflux disease often presents as heartburn and acid reflux, the so-called "typical" symptoms. However, a subgroup of patients presents a collection of signs and symptoms that are not directly related to esophageal damage. These are known collectively as the extraesophageal manifestations of gastroesophageal reflux disease. Principal among such manifestations are bronchospasm, chronic cough and laryngitis, which are classified as atypical symptoms. These manifestations comprise a heterogeneous group. However, some generalizations can be made regarding all of the subgroups. First, although the correlation between gastroesophageal reflux disease and the extraesophageal manifestations has been well established, a cause-and-effect relationship has yet to be definitively elucidated. In addition, the main proposed pathogenic mechanisms of extraesophageal reflux are direct injury of the extraesophageal tissue (caused by contact with gastric acid) and the esophagobronchial reflex, which is mediated by the vagus nerve. Furthermore, gastroesophageal reflux disease might not be considered in the differential diagnosis of patients presenting only the atypical symptoms. In this article, we review the extraesophageal manifestations of gastroesophageal reflux disease, discussing its epidemiology, pathogenesis, diagnosis and treatment. We focus on the most extensively studied and well-established presentations.

High prevalence of proximal and distal gastroesophageal reflux disease in advanced COPD

BACKGROUND

Gastroesophageal reflux disease (GERD) is common in a variety of chronic respiratory diseases, but little is known about GERD in the setting of COPD. The aims of this study were to determine the prevalence, presentation, and predictors of GERD based on proximal and distal esophageal pH monitoring in patients with severe COPD.

METHODS

Forty-one COPD patients with a mean FEV1 of 24% of predicted underwent dual-probe 24-h esophageal pH monitoring, and 1 patient underwent esophagogastroduodenoscopy.

RESULTS

The prevalence of GERD was 57%. Elevated distal and proximal reflux were present in 41% and 46% of patients undergoing esophageal pH studies, respectively. Fifteen percent of these patients had abnormal proximal reflux despite having normal distal probe results. Most patients with GERD were not receiving acid blockers at the time of their referral, and only one third reported heartburn and/or acid regurgitation during the pH study. Only higher body mass index was predictive of reflux on regression analysis (odds ratio, 1.2; 95% confidence interval, 1.0 to 1.5; p = 0.05).

CONCLUSIONS

GERD is common in advanced COPD. Patients are often asymptomatic and have a relatively high prevalence of isolated abnormal proximal reflux. Dual-probe monitoring is therefore well suited for detecting GERD in patients with advanced COPD.

Omeprazole reduces the response to capsaicin but not to methacholine in asthmatic patients with proximal reflux

OBJECTIVE

To study the relationships between airway responsiveness to methacholine and capsaicin, proximal or distal reflux and the effects of short-term acid inhibition.

MATERIAL AND METHODS

Twenty-nine asthmatics, not taking steroids regularly, underwent respiratory symptom measurements, 24-h dual-probe pH monitoring, and challenges with methacholine and capsaicin. Challenges and symptom measurements were repeated after 12 days' omeprazole treatment (20 mg b.i.d.). The results (median and range) were expressed as PD20 methacholine (mg) and PD5 capsaicin (dose causing five coughs, nmol).

RESULTS

Seventeen patients presented pathological reflux in the distal esophagus, and 17 in the proximal esophagus. At baseline no correlation was found between PD20 or PD5 and reflux. Treatment with omeprazole did not change bronchial responsiveness to methacholine (basal: 0.16 mg, 0.02-1.27; omeprazole: 0.15 mg, 0.02-1.60); omeprazole decreased the tussive response to capsaicin (basal: 0.08 nmol, 0.08-2.46; omeprazole: 0.61 nmol, 0.08-9.84, p<0.001) only in patients with pathological reflux. The decrease was positively correlated with proximal acid exposure (r2=0.70, p<0.001). Omeprazole reduced asthma symptoms in patients with proximal reflux, cough in those with proximal or distal reflux.

CONCLUSIONS

In asthmatics, inhibition of gastric acid secretion does not influence bronchial hyperresponsiveness but decreases tussive sensitivity and this effect is related to proximal reflux.

The relation between gastroesophageal reflux and respiratory symptoms in a population-based study: the Nord-Trøndelag health survey

BACKGROUND

In spite of numerous investigations, the relation between respiratory symptoms and reflux symptoms in the general population remains unclear, since population-based studies are few.

STUDY OBJECTIVES

To investigate the relation between respiratory symptoms and reflux symptoms in the population.

SUBJECT AND METHODS

In a cohort of 65,363 individuals representing 71.2% of the adult population in the Norwegian county of Nord-Trøndelag, 58,596 individuals (89.6%) responded to questions concerning reflux symptoms. The 3,153 persons (5.4%) with severe and recurrent reflux symptoms constituted the case group, and the 40,210 persons (68.6%) without reflux symptoms served as the control group. Odds ratios (ORs) with 95% confidence intervals (CIs) represented relative risks. Potential confounding was tested in multivariable logistic regression analysis.

RESULTS

Persons with asthma had reflux to a 60% greater extent than those without asthma after including adjustment for asthma medication (OR, 1.6; 95% CI, 1.4 to 1.9). There was a statistically significant dose-response association between breathlessness and reflux symptoms (p for trend < 0.0001), and the OR of severe breathlessness was 12.0 (95% CI, 9.5 to 15.2). Persons with heavy and wheezy breathing, daily cough, daily productive cough, or chronic cough showed a twofold to threefold statistically significant increase in risk of reflux symptoms. Adjustment for asthma or use of asthma medication did not substantially influence the risk estimates for any of the studied respiratory disorders.

CONCLUSIONS

Reflux symptoms commonly coexist with asthma and other respiratory symptoms on a population-based level, seemingly irrespective of asthma medication.

Barrett's esophagus and medications that relax the lower esophageal sphincter

OBJECTIVES

Medications that may increase gastroesophageal reflux could be risk factors for esophageal adenocarcinoma; however, epidemiologic studies present conflicting results. We evaluated patients with a high-risk condition, Barrett's esophagus, to identify risk factors that may act early in the carcinogenic process.

METHODS

We conducted a nested case-control study within a large integrated health-services organization. Electronic databases were used to identify incident diagnoses of Barrett's esophagus (cases); two controls were matched to each case. Electronic databases provided information on the use of medications that may induce reflux (nitrates, calcium channel blockers, xanthines, benzodiazepines, and beta agonists) and potential confounders. A supplemental mailed questionnaire evaluated additional potential confounders.

RESULTS

We identified 421 cases and selected 842 controls. The association between any medication use and a Barrett's esophagus diagnosis was modified by age; an increased risk was observed only among subjects <70 yr of age (adjusted odds ratio [OR] = 2.6; 95% confidence interval [CI] 1.5-4.6). A Barrett's esophagus diagnosis was associated with asthma medication use (OR 5.8; 95% CI 2.2, 14.9), but not with the other medications studied. Subgroup analyses suggested that medication use was not independently associated with reflux symptoms and that adjustment for asthma symptoms substantially reduced the association between medication use and a Barrett's esophagus diagnosis.

CONCLUSION

The use of medications that may induce reflux was associated with a Barrett's esophagus diagnosis among younger persons. This association was only observed with asthma medications; the analyses suggested the possibility of confounding by indication, whereby reflux may cause both asthma and Barrett's esophagus.

Differential diagnosis of chest symptoms in the athlete

Chest pain is a common complaint of athletes in all age groups. In athletes, chest pain is often attributed to "chest tightness," and treatment for bronchospasm is considered. However, the causes of the pain are wide and varied, and the pain is referable to the many organ systems that localize to the thorax. Therefore, when treatment with bronchodilators fails, it becomes important to consider other nonasthmatic causes of the pain. These causes can be organized by system and are explained in this article. Cardiac causes are the most feared and, fortunately, are very rare in the adolescent setting. With a thorough knowledge of etiologies of chest pain, the physician can often make a diagnosis with only a history and a physical exam.

Chronic Cough Due to Gastroesophageal Reflux Disease

OBJECTIVES

To critically review and summarize the literature on cough and gastroesophageal reflux disease (GERD), and to make evidence-based recommendations regarding the diagnosis and treatment of chronic cough due to GERD.

DESIGN/METHODOLOGY

Ovid MEDLINE literature review (through March 2004) for all studies published in the English language and selected articles published in other languages such as French since 1963 using the medical subject heading terms "cough," "gastroesophageal reflux," and "gastroesophageal reflux disease."

RESULTS

GERD, singly or in combination with other conditions, is one of the most common causes of chronic cough. In patients with normal chest radiographic findings, GERD most likely causes cough by stimulation of an esophageal-bronchial reflex. When GERD causes cough, there may be no GI symptoms up to 75% of the time. While 24-h esophageal pH monitoring is the most sensitive and specific test in linking GERD and cough in a cause-effect relationship, it has its limitations. In addition, there is no general agreement on how to best interpret the test, and it cannot detect non-acid reflux events. Therefore, when patients fit the clinical profile that has a high likelihood of predicting that GERD is the cause of cough, antireflux medical therapy should be empirically instituted. While some patients improve with minimal medical therapy, others require more intensive regimens. When empiric treatment fails, it cannot be assumed that GERD has been ruled out as a cause of chronic cough. Rather, an objective investigation for GERD is then recommended because the empiric therapy may not have been intensive enough or medical therapy may have failed. Surgery may be efficacious when intensive medical therapy has failed in selected patients who have undergone an extensive objective GERD evaluation.

CONCLUSIONS

Accurately diagnosing and successfully treating chronic cough due to GERD can be a major challenge.

Beyond heartburn: a systematic review of the extra-oesophageal spectrum of reflux-induced disease

BACKGROUND

Gastro-oesophageal reflux disease (GORD) is a chronic condition affecting up to one-quarter of the Western population. GORD is characterized by heartburn and acid regurgitation, but is reported to be associated with a spectrum of extra-oesophageal symptoms.

OBJECTIVE

The aim of this systematic review was to critically evaluate postulated extra-oesophageal symptoms of GORD.

METHODS

Extra-oesophageal symptoms were identified from population-based studies evaluating their association with GORD (either defined as heartburn and/or acid regurgitation, or diagnosed in general practice). The response of these symptoms to acid-suppressive therapy was investigated using randomized, double-blind, placebo-controlled studies. Pathogenic mechanisms were evaluated using clinical and preclinical studies.

RESULTS

An association between GORD and symptoms or a diagnosis of chest pain/angina, cough, sinusitis and gall-bladder disease was evident from three eligible population-based studies of GORD. Randomized placebo-controlled studies (n=20) showed that acid-suppressive therapy provides symptomatic relief of chest pain, asthma and, potentially, chronic cough and laryngitis. Mechanistic models, based on direct physical damage by refluxate or vagally mediated reflexes, support a causal role for GORD in chest pain and respiratory symptoms, but not in gall-bladder disease.

CONCLUSION

GORD is likely to play a causal role in chest pain and possibly asthma, chronic cough and laryngitis. Further investigation is desirable, particularly for other potential extra-oesophageal manifestations of GORD such as chronic obstructive pulmonary disease, sinusitis, bronchitis and otitis. Acid-suppressive therapy is likely to benefit patients with non-cardiac chest pain, but further placebo-controlled studies are needed for other symptoms comprising the extra-oesophageal spectrum of GORD.

Gastroesophageal reflux disease in children with asthma: treatment implications

An association between asthma and gastroesophageal reflux disease (GERD) has long been recognized both mechanistically and epidemiologically. The clinical relevance of this interplay continues to be explored, with special interest given to the role of GERD in the worsening of asthma. The effect of GERD is most frequently contemplated in patients with asthma that is difficult to control. Medical and surgical anti-reflux trials attempting to alter asthma symptoms have reported mixed but generally underwhelming results, although asthma symptom scores are generally improved following effective treatment of GERD. Many of the pharmaceutical studies can be criticised for having too short a duration or for likely incomplete acid suppression. Few trials have specifically studied pediatric populations. Because GERD is a common condition, particularly in young children, the role reflux plays in the worsening of asthma symptoms and the potential benefit on asthma of anti-reflux therapy warrants further exploration. Whether or not treating symptomatic GERD reduces the symptoms and severity of asthma in children, GERD coexisting with asthma should be aggressively treated. GERD symptoms in most patients with or without asthma can be controlled medically with continuous use of proton pump inhibitors such as omeprazole and lansoprazole and to a lesser extent by histamine H(2) receptor antagonists such as famotidine and cimetidine.

Gastro-oesophageal reflux and bronchial asthma: current status and future directions

In recent years there have been several reports suggesting an association between bronchial asthma and gastro-oesophageal reflux; however a cause and effect relationship has not been proven yet. Confirmation of such a relationship is likely to have far reaching implications on the management of asthma. Reliable assessment of this issue is hampered by the presence of various lacunae in most of the published studies. Hence it is essential to carefully examine the strength of data suggesting a link between asthma and reflux. This article critically analyses currently available literature on the subject (including published reviews, meta-analyses, and randomised clinical trials in the English language) and summarises valid conclusions that can be drawn; it also proposes a framework for future studies to resolve the issue.

Gastroesophageal reflux: a potential asthma trigger

Gastroesophageal reflux (GER) is a potential trigger of asthma. Approximately 77% of asthmatics report heartburn. GER is a risk factor for asthma-related hospitalization and oral steroid burst use. Asthmatics may be predisposed to GER development because of a high prevalence of hiatal hernia and autonomic dysregulation and an increased pressure gradient between the abdominal cavity and the thorax, over-riding the lower esophageal sphincter pressure barrier. Asthma medications may potentiate GER. Potential mechanisms of esophageal acid-induced bronchoconstriction include a vagally mediated reflex, local axonal reflexes, heightened bronchial reactivity, and microaspiration, all resulting in neurogenic inflammation. Anti-reflux therapy improves asthma symptoms in approximately 70% of asthmatics with GER. A 3-month empiric trial of twice-daily proton pump inhibitor given 30 to 60 minutes before breakfast and dinner can identify asthmatics who have GER as a trigger of their asthma.

Clinical presentation, diagnosis, and management of gastroesophageal reflux disease

GERD is ubiquitous throughout the adult population in the United States. It commonly adversely affects quality of life and occasionally causes life-threatening complications. The new and emerging medical and endoscopic therapies for GERD and the new management strategies for BE should dramatically reduce the clinical toll of this disease on society.

Mechanisms of gastroesophageal reflux in critically ill mechanically ventilated patients

BACKGROUND & AIMS

Gastroesophageal reflux is a major problem in mechanically ventilated patients and may lead to pulmonary aspiration and erosive esophagitis. Transient lower esophageal sphincter relaxations are the most common mechanism underlying reflux in nonventilated patients. The mechanisms that underlie reflux in critically ill ventilated patients have not been studied. The aim of this study was to determine the mechanisms underlying gastroesophageal reflux in mechanically ventilated patients in the intensive care unit.

METHODS

In 15 mechanically ventilated intensive care unit patients, esophageal motility, pH, and intraluminal impedance (11/15 patients) were recorded for 1 hour before and 5 hours during continuous nasogastric feeding.

RESULTS

Basal lower esophageal sphincter pressure was uniformly low (2.2 +/- 0.4 mmHg). The median (interquartile range) acid exposure (pH <4) was 39.4% (0%-100%) fasting and 32% (7.5%-94.2%) fed. Acid reflux occurred in 10 patients, but slow drifts in esophageal pH were also an important contributor to acid exposure. If esophageal pH decreased to pH <4, it tended to remain so for prolonged periods. A total of 46 acid reflux events were identified. Most (55%) occurred because of absent lower esophageal sphincter pressure alone; 45% occurred during straining or coughing.

CONCLUSIONS

Gastroesophageal reflux in mechanically ventilated patients is predominantly due to very low or absent lower esophageal sphincter pressure, often with a superimposed cough or strain. These data suggest that measures that increase basal LES pressure may be useful to prevent reflux in ventilated patients.

Clinical manifestations and complications of gastroesophageal reflux disease (GERD)

Gastroesophageal reflux-induced diseases are among the most common disorders and are associated with classical oesophageal manifestations of gastroesophageal reflux disease (GERD) including a range of symptoms such as heartburn, acid regurgitation and chest pain, and also organic manifestations such as oesophagitis, oesophageal strictures and ulcerations, Barrett's oesophagus and oesophageal adenocarcinoma. Recognition of its impact on other organ systems, extra-oesophageal reflux diseases, such as the ear, nose and throat (ENT) region and the bronchopulmonary system, as well as its contribution to symptoms such as chest pain and sleep disturbances, is also increasing. This paper addresses the symptoms, diseases and complications in which the abnormal reflux of gastric content to the oesophagus and adjacent organ systems is believed to be a frequent contributory factor.

The prevalence of gastroesophageal reflux disease in adult asthmatics

BACKGROUND

Asthma and gastroesophageal reflux disease (GERD) often coexist. However, the results of the studies investigating the prevalence of GERD among patients with asthma vary greatly.

STUDY OBJECTIVE

To investigate the prevalence of GERD in adult patients with asthma.

SUBJECTS AND METHODS

The basic study population consisted of 2,225 asthmatic patients who were treated in six specialist-headed hospitals during 1 year. From the common computer-based discharge register, every 14th patient was randomly selected for the study. Ninety of the 149 contacted patients (60%) agreed to participate in the study. Twenty-four-hour esophageal pH monitoring was performed on all patients.

RESULTS

GERD was found in 32 of the patients (36%). Eight of these patients (25%) were free from classical reflux symptoms. Forty-seven of the 90 patients (52%) presented with typical reflux symptoms. Twenty-four of these patients (51%) were found to have abnormal acidic reflux.

CONCLUSIONS

According to the current study, one third of adult patients with asthma have GERD. These patients often do not have typical reflux symptoms. However, the presence of typical reflux symptoms in an asthmatic patient does not seem to guarantee the presence of abnormal acidic reflux.

Responses of human clasp and sling fibers to neuromimetics

BACKGROUND AND AIMS

It has previously been demonstrated that clasp and sling fibers at the human gastroesophageal junction respond differently to acetylcholine (Ach). The present study was undertaken to investigate the differences between the physiological and pharmacological properties of the two types of muscle fiber.

METHODS

Recordings were made of the isometric tension of human sling and clasp fibers in response to Ach, dopamine (DA), phenylephrine (Phe), and isoprenaline (Iso). These specimens were obtained from 18 patients who were operated on for esophageal cancer.

RESULTS

Both Ach and Phe increased the tension of the two types of muscle; the values in the Ach group being 3-4-fold greater than those in the Phe group, while Iso decreased the tension of both types of muscle strip. The tension of the sling fibers was reduced by DA at lower concentration, and then increased gradually as the concentration was increased. In contrast, the tension of the clasp fibers did not obviously change when the concentration of DA was lower, but a slow elevation of tension was seen with the increase in DA concentration.

CONCLUSIONS

The sensitivities and maximum responses to each agent differed between the clasp fibers and sling fibers. This suggests that the two kinds of fiber have different roles in establishing tension in the lower esophageal sphincter, with implications for the medical and surgical treatment of disorders in this region.

Clinical implications of gastroesophageal reflux disease and swallowing dysfunction in COPD

The intimate anatomical and physiologic relationship between the upper airway and esophagus consists of complex interactions between various muscles and nerves with both voluntary and involuntary patterns of control. Alterations in this harmonic relationship can lead to swallowing abnormalities ranging from dysphagia to gross aspiration, gastroesophageal reflux disease (GERD) and chronic cough. There is a paucity of data regarding pathologic alterations in the upper airway-esophageal relationship in patients with COPD. The association between GERD and respiratory symptoms is well recognized in the setting of asthma; however, the nature of this relationship remains controversial. The association of GERD and COPD is even less clear. A review of the limited data on GERD and swallowing abnormalities in patients with COPD indicate that prevalence of GERD and esophageal disorders in patients with COPD is higher than in the normal population. However, its contribution to respiratory symptoms, bronchodilator use and pulmonary function in patients with COPD remains unknown. Although dysphagia and swallowing dysfunction on videofluoroscopic swallow evaluation are common in patients with COPD, their role as exacerbators of COPD remains to be elucidated. Further clinical research is necessary to evaluate the role of GERD and swallowing dysfunction in both stable and acute exacerbation of COPD.

Extraesophageal manifestations of GERD

The association between gastroesophageal reflux disease (GERD) and extraesophageal disease is often referred to as extraesophageal reflux (EER). This article reviews EER, discussing epidemiology, pathogenesis, diagnosis, and treatment with a focus on the most studied and convincing EER disorders-asthma, cough, and laryngitis. Although EER comprises a heterogeneous group of disorders, some general characterizations can be made, as follows. First, although GERD's association with extraesophageal diseases is well-established, definitive evidence of causation has been more elusive, rendering epidemiological data scarce. Secondly, regarding the pathogenesis of EER, 2 basic models have been proposed: direct injury to extraesophageal tissue by acid and pepsin exposure or injury mediated through an esophageal reflex mechanism. Third, because heartburn and regurgitation are often absent in patients with EER, GERD may not be suspected. Even when GERD is suspected, the diagnosis may be difficult to confirm. Although endoscopy and barium esophagram remain important tools for detecting esophageal complications, they may fail to establish the presence of GERD. Even when GERD is diagnosed by endoscopy or barium esophagram, causation between GERD and extraesophageal symptoms cannot be determined. Esophageal pH is the most sensitive tool for detecting GERD, and it plays an important role in EER. However, even pH testing cannot establish GERD's causative relationship to extraesophageal symptoms. In this regard, effective treatment of GERD resulting in significant improvement or remission of the extraesophageal symptoms provides the best evidence for GERD's pathogenic role. Finally, EER generally requires more prolonged and aggressive antisecretory therapy than typical GERD requires.

Medication-induced oesophageal disorders

Medication-induced oesophageal distress and injury have become increasingly common conditions. First, smooth muscle relaxants may worsen or produce symptoms of pre-existing gastro-oesophageal reflux disease; notable examples include certain calcium antagonists (nifedipine), nitrates, sildenafil, nicotine, theophylline, and substances with antimuscarinic potential. Second, drugs with local toxicity may produce de novo damage including inflammation, strictures, ulcers, and bleeding. Notorious examples are alendronate, certain antibiotics including tetracyclines and clindamycin, all NSAIDs/aspirin, quinidine, potassium chloride, and ferrous sulfate. Cyclooxygenase-2 inhibitors may be devoid of such toxicity, but may damage the mucosa by interfering with regenerative cell proliferation. The galenic formulation can modulate the risk of oesophageal injury. For this reason, medicines containing the same potentially toxic ingredient may be less exchangeable than commonly thought. Diagnostic gold standard is endoscopy. The best treatment is removal of the offending drug and supportive care. Prevention requires a re-appraisal of the drug's indication and adherence to guidelines of optimal drug intake including ingestion in an upright position and swallowing with enough fluid. The clinical relevance of drug-induced oesophageal injury and the feasibility of therapeutic alternatives are individually addressed.

Recent clinical investigations examining the association of asthma and gastroesophageal reflux

For more than a decade, investigations have examined the association between asthma and gastroesophageal reflux (GER), and have demonstrated that the presence of esophageal acid events is associated with respiratory symptoms. The most current research shows that GER is prevalent in patients with asthma, that esophageal acid may alter bronchial hyperresponsiveness, and that medical or surgical GER therapy may improve asthma outcome in selected asthma patients. Further research will build on our current knowledge base and, hopefully, enable us to better identify those patients with asthma who will most benefit from reflux therapy.

The role of proton pump inhibitors in the management of gastroesophageal reflux disease-related asthma and chronic cough

Gastroesophageal reflux disease (GERD) occurs in at least one third of patients with asthma and is recognized as a potential trigger for asthma symptoms. The results of studies conducted in patients with both asthma and GERD, in which proton pump inhibitor (PPI) therapy is used to evaluate its effect on asthma outcome, are inconsistent, and many of these studies suffer from different design flaws. However, it does appear that PPI treatment may improve nocturnal asthma symptoms in patients who also have GERD. Moreover, both daytime asthmatic symptoms and pulmonary function seem to improve in some patients with PPI treatment. There is evidence that more severe GERD might predict a more favorable asthma outcome with PPI therapy. For effective management of GERD-related asthma, PPIs should be used at a dose double that of the standard dose for a minimum of 2 to 3 months. Although GERD is also known to be an important cause of chronic cough, there have been only 2 placebo-controlled trials investigating the efficacy of PPI on GERD-related chronic cough. Results of both of these trials suggest that PPI treatment relieves GERD-related chronic cough. As with GERD-related asthma, it would seem reasonable to use a double-standard dose of a PPI for a minimum of 2 to 3 months in the management of GERD-related chronic cough. However, larger, adequately planned studies are needed to confirm the role of PPIs in the management of GERD-related asthma and chronic cough.

Esophageal motor disorders

Refinements continue in the measurement, display, and interpretation of pressure events that serve as signatures of esophageal motor disorders, and esophageal manometry retains its position as the diagnostic gold standard. The focus of attention remains with achalasia, not because of pathophysiologic developments or changing prevalence, but in response to the growing interest in minimally invasive surgery and its success. Some controversy remains regarding the role of preoperative motility assessments in patients undergoing antireflux surgery, as peristaltic features do not solely predict outcome. The disconnect between motor dysfunction and symptoms continues to promote careful consideration of sensory dysfunction as a component of esophageal motor disorders.