Chronic Cough Due to Gastroesophageal Reflux Disease

Clinical benefit of sequential three-step empirical therapy in the management of chronic cough

BACKGROUND AND OBJECTIVE

A prospective study was conducted to investigate the efficacy of empirical therapy in the management of chronic cough.

METHODS

A three-step empirical therapy protocol was used to treat patients who had a chronic cough and a normal CXR and normal lung function testing. In step one antihistamine decongestants plus bronchodilators were taken, corticosteroids in the second step, and a combination of a proton pump inhibitor and a prokinetic agent in the third step. Cough symptom scores were recorded before and after each step in the protocol.

RESULTS

There were 102 patients recruited; mean age 49 +/- 16 years and with a history of cough of between 2 and 120 months at presentation. The cough resolved in 67.6% (n = 69) of the patients after the first-step therapy; in a further 12.7% (13) after the second-step therapy, and in another 7.8% (8) after the third-step of the treatment protocol. In three patients cough improved after the first-step of therapy but only achieved complete resolution when this treatment was combined with the third-step therapy. Overall, the three-step empirical therapy was successful in 88.2% (n = 90) of the patients. Cough symptom scores decreased from 3.30 +/- 0.75 to 0.30 +/- 0.97 (P < 0.001). The mean duration of treatment was 2.70 +/- 1.52 weeks (range 1-12). Cough was controlled in <4 weeks in 79.4% (n = 81) of patients.

CONCLUSIONS

Three-step empirical therapy seemed to be useful in most patients and has practical application in the management of chronic cough.

Gastroesophageal reflux-associated chronic cough in an adolescent and the diagnostic implications: a case report

A 15-year-old girl was referred with a 2-year history of perennial non-productive cough, which had been preceded by Mycoplasma pneumoniae pneumonia and subsequent asthma. Symptoms were only partially responsive to anti-asthma treatment including an inhaled corticosteroid and a leukotriene receptor antagonist. The patient's BMI was 27.8; she had gained over 10 kg in the previous two years. Typical symptoms of gastroesophageal reflux disease were not evident except for belch. Coughing worsened on eating and rising from bed. Although esophagography failed to disclose reflux esophagitis, esophageal pH monitoring revealed significant acid reflux. Asthma was considered well controlled. Treatment with the proton-pump inhibitor rabeprazole resulted in disappearance of cough. Frequency Scale for the Symptoms of Gastroesophageal reflux disease (FSSG) score, a questionnaire evaluating the symptoms of gastroesophageal reflux disease, was initially high but normalized after treatment. Capsaicin cough sensitivity also diminished with treatment.Chronic cough due to gastroesophageal reflux disease has been considered rare in adolescents, but this condition might be increasing in line with the recent trend in adults. Clinical features of gastroesophageal reflux disease-associated cough typical for adult patients and a specific questionnaire for evaluating gastroesophageal reflux disease validated in adults may also be useful diagnostic clues in adolescents.

Laryngitis: types, causes, and treatments

Inflammatory processes that affect the unified airway can concurrently exert significant influence on the larynx and surrounding mucosal surfaces. Laryngeal inflammation can be present secondary to direct effects of irritants, toxins, and antigens, but can also involve mechanical and infectious effects as well as secondary inflammation from behavioral mechanisms. This review examines laryngeal inflammation in the context of the unified airway and discusses pathophysiologic mechanisms that are central to the development of acute and chronic laryngitis.

Ultrastructural changes in the epithelium in asthma associated with gastroesophageal reflux

Asthma concomitant with gastroesophageal reflux is regarded in the context of systemic multifactorial primary degenerative process, based on discoordination of neurohormonal regulation and systemic metabolic and degenerative changes. Degeneration and atrophy of the structural components of the bronchial tree and gastric wall are the leading phenomenons determining the organ dysfunction.

Common causes and current guidelines

Chronic cough is a common and disabling symptom. Recent guidelines have attempted to provide direction in the clinical management of cough in both primary and secondary care. They have also provided a critical review of the available literature and identified gaps in current knowledge. Despite this they have been criticized for a reliance on a low quality evidence base. In this review, we summarize the current consensus on the clinical management of chronic cough and attempt to rationalize this based on recent evidence. We have also provided an overview of the likely pathophysiological mechanisms responsible for cough and highlighted areas, where knowledge deficits exist and suggest directions for future research. Such progress will be critical in the search for new and effective treatments for cough.

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.

Acidification of the oesophagus acutely increases the cough sensitivity in patients with gastro-oesophageal reflux and chronic cough

Gastro-oesophageal reflux disease (GORD) is one of the most common causes of chronic cough; however, the mechanisms by which GOR initiates coughing are incompletely understood. We address the hypothesis that acidification of oesophagus acutely increases the cough reflex sensitivity in patients with GORD and chronic cough. Nine patients with GORD with chronic cough and 16 patients with GORD without cough were recruited. In a randomized double blind study, saline and acid (HCl, 0.1 mol L(-1)) were separately infused into oesophagus via naso-oesophageal catheter. Cough reflex sensitivity to inhaled capsaicin was determined immediately after completion of each infusion. Infusion of acid into oesophagus increased capsaicin cough reflex sensitivity in patients with GORD and chronic cough. In contrast, acid had no effect on the cough sensitivity in patients with GORD without cough. In a separate study, acid infusion into oesophagus did not affect the cough sensitivity in 18 healthy subjects. We conclude that acid in the oesophagus acutely increases the cough reflex sensitivity to capsaicin in patients with GORD and chronic cough. This phenomenon may contribute to the pathogenesis of cough due to GORD.

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.

Gastroesophageal reflux disease and chronic cough

Gastroesophageal reflux disease (GERD) is a common cause of unexplained chronic cough. This article reviews important clinical considerations regarding association, diagnosis, and treatment of GERD in the setting of chronic unexplained cough.

Therapy Insight: treatment of gastroesophageal reflux in adults with chronic cough

Gastroesophageal reflux (GER) is the second most common cause of chronic cough in immunocompetent patients who are nonsmokers, not on angiotensin-converting-enzyme inhibitors and have normal chest radiographs. Identification of GER in chronic cough patients can be difficult; most patients with GER-related cough have no esophageal symptoms and no esophageal test is adequate to make this diagnosis. Post-hoc analysis of four prospective intervention trials has identified a clinical patient profile that can predict the presence of GER-related cough 91% of the time. Clinical practice guidelines from the American College of Chest Physicians and the British Thoracic Society recommend initiating an initial empiric GER therapy trial, with esophageal testing being reserved for nonresponders. The empiric trial should include conservative measures and PPIs twice daily for 3 months. Selected patients who have dysphagia might benefit from the addition of a prokinetic agent. Esophageal manometry and pH testing with impedance monitoring (if available) should be performed in nonresponders while they are on therapy. It can take more than 50 days for cough to respond to medical GER therapy. Surgical fundoplication might be helpful in very carefully selected patients. Careful evaluation and treatment resolves cough in approximately 80% of patients with GER-related cough.

Chronic cough: the allergist's perspective

Cough is a common presenting symptom of many patients managed by allergists. For patients with chronic cough who are nonsmokers, have normal spirometry, and are not being treated with an ACE inhibitor, diagnosis usually focuses on differentiation between postnasal drip syndrome, asthma, gastroesophageal reflux disease, and nonasthmatic eosinophilic bronchitis, alone or in combination. Patients with severe COPD or GERD should be referred to appropriate specialists for those conditions. The management of conditions commonly treated by allergists (e.g., allergic rhinitis, asthma, sinusitis) follows the recommendations of current guidelines and/or practice parameters.

[Results of laparoscopic fundoplication in gastroesophageal reflux disease with atypical manifestations]

INTRODUCTION

Gastroesophageal reflux disease (GERD) may present with typical (heartburn and regurgitation) and atypical symptoms (cough, asthma, non-cardiac chest pain). Laparoscopic fundoplication has been performed for approximately 10 years, with results similar to or better than those obtained with open antireflux procedures. The aim of this study was to evaluate the clinical and functional results of laparoscopic fundoplication in patients with GERD and atypical symptoms.

PATIENTS AND METHOD

There were 158 consecutive patients with GERD who underwent a 360 degrees laparoscopic fundoplication (January 1999 to March 2006) and 27 patients had atypical symptoms. All patients underwent preoperative manometry and 24 hour pH-metry and 78% underwent the same tests postoperatively (at 6 months). Data from hospital records were analyzed and a clinical telephone survey was conducted.

RESULTS

There was no mortality and no conversions were required. The median length of follow-up was 21 months. All atypical symptoms (cough, chest pain, asthma, dysphonia and hoarseness) were significantly reduced (p < 0.05). There was no relationship between symptom persistence in five patients and pathologic acid reflux, except in one patient. Eighty-nine percent of the patients responded to the telephone survey; of these, 79% had no symptoms. The median satisfaction score was 9 (from 0 to 10).

CONCLUSIONS

Laparoscopic fundoplication for GERD with atypical symptoms is a safe procedure with good results (clinical and functional) in trained groups patients. Moreover a high satisfaction rate is obtained.

Extra-esophageal manifestations of gastroesophageal reflux

Gastroesophageal reflux disease (GERD) is a common medical condition affecting approximately 35-40% of the adult population in the western world. The role of GERD in causing extra-esophageal symptoms including laryngitis, asthma, cough, chest pain, and dental erosions is increasingly recognized with renewed interest among gastroenterologists and other specialists. Direct injury by mucosal contact, and vagally mediated reflex from distal esophageal acid exposure are the two possible mechanisms by which reflux-related extra-esophageal tissue injuries may occur. Several investigational techniques may be used to diagnose gastroesophageal reflux; however, because of the poor sensitivity of endoscopy and pH monitoring, and the poor specificity of laryngoscopy, empiric therapy with proton-pump inhibitors (PPI) is now considered the initial diagnostic step in patients suspected of having GERD-related symptoms. In those who improve with such therapy, it is likely that GERD may be the cause of the extra-esophageal presentation. In those who are unresponsive to such therapy, other diagnostic testing such as impedance/pH monitoring may be reasonable in order to exclude continued acid or weakly acid reflux. However, PPI-unresponsive patients usually have causes other than GERD for the extra-esophageal symptoms and signs.

The utility of ambulatory pH monitoring in patients presenting with chronic cough and asthma

OBJECTIVE

To evaluate the prevalence of gastroesophageal reflux disease (GERD) in patients presenting with asthma and chronic cough.

PATIENTS AND METHODS

The charts of 358 consecutive patients who were referred for ambulatory gastroesophageal pH monitoring to the Lung Centre in Vancouver, British Columbia, were reviewed, and the data of 108 (30%) patients with asthma and 134 (37%) patients with chronic cough were analyzed. The maintenance treatment for GERD was discontinued before patients underwent the pH monitoring study. One hundred eighteen (33%) patients were excluded.

RESULTS

Reflux episodes identified reflux events as the percentage of time where the pH was less than four. For asthma patients, 70 (64.8%) had distal total reflux, 50 (46.3%) had distal upright reflux, 41 (38.3%) had distal supine reflux and 73 (67.6%) had other distal refluxes. Proximal total reflux in asthmatic patients was present in 56 (52%), proximal upright reflux in 55 (51%) and proximal supine reflux in 56 (52%) patients. For chronic cough patients, 70 (52.6%) had distal total reflux, 59 (44.4%) had distal upright reflux, 45 (34.4%) had distal supine reflux and 75 (56%) patients had other distal refluxes. In chronic cough patients, proximal total reflux was present in 70 (52%), proximal upright reflux in 80 (60%) and proximal supine reflux in 59 (44%). Presenting respiratory and/or reflux symptoms were absent in approximately 25% of patients with asthma and reflux, and in approximately 50% of patients with chronic cough and reflux. During pH monitoring, symptoms did not differ significantly between those with and without distal reflux in both study groups, except for more significant heartburn in patients with chronic cough and reflux (RR 2.0).

CONCLUSIONS

The data of the present study support the observation that there is a high prevalence of GERD in patients with asthma or chronic cough. The use of different pH parameters for detecting acid reflux during 24 h ambulatory pH monitoring, such as proximal esophageal acid measurement, should be considered as part of the routine interpretation of such testing. A low threshold for diagnosing GERD in patients with asthma or chronic cough is essential, because respiratory and/or reflux symptoms can be absent or atypical in some of these patients.

Taming chronic cough

OBJECTIVE

To review the available evidence on treating chronic cough to relay a thoughtful, evidence-based approach for the diagnosis and treatment of chronic cough.

DATA SOURCES

MEDLINE, PubMed, EMBASE, and CINAHL were searched using the following keywords: cough, asthma, gastroesophageal reflux, sinusitis, rhinitis (allergic, seasonal), postnasal drip, vocal cord dysfunction, lung disease (interstitial), bronchiectasis, and bronchoscopy.

STUDY SELECTION

Studies were selected based on their relevance to the diagnosis and treatment of chronic cough. Because of a lack of randomized prospective studies, nonrandomized and retrospective studies were considered, with their strengths and limitations noted.

RESULTS

Few randomized controlled trials have addressed the diagnosis and treatment of chronic cough. There are several prospective noncontrolled trials for adults with chronic cough that found a high percentage of cough resolution when using an approach that focused on the diagnosis and treatment of the most common causes: asthma, gastroesophageal reflux disease, and upper airway cough syndrome. Preliminary studies in children support an approach that distinguishes between a wet and dry cough, as well as an in-depth investigation of any specific symptoms that point to an underlying chronic illness.

CONCLUSION

Allergists, as experts in treating upper airway and lower airway disorders, are uniquely poised to diagnose and treat chronic cough.

Defining the relationship between gastroesophageal reflux and cough: probabilities, possibilities and limitations

The common co-existence of cough and gastroesophageal reflux disease (GORD) is well established. However, ascertaining cause and effect is more difficult for many reasons that include occurrence by chance of two common symptoms, the changing definition of GORD, equipment limitations and the lack of randomised controlled trials. Given these difficulties, it is not surprising that there is disparity of opinion between respiratory and gastroenterology society guidelines on the link between GORD and chronic cough. This commentary explores of these issues.

Improved diagnosis of gastro-oesophageal reflux in patients with unexplained chronic cough

BACKGROUND

Symptoms, oesophageal pHmetry and proton pump inhibitor treatment are used for diagnosing gastro-oesophageal reflux-related cough. Weakly acidic reflux is now increasingly associated with reflux symptoms such as regurgitation or chest pain.

AIM

To study the association between weakly acidic reflux and cough in a selected, large group of patients with unexplained chronic cough.

METHODS

A total of 100 patients with chronic cough (77 'off' and 23 'on' a proton pump inhibitor) were studied using impedance-pHmetry for reflux detection and manometry for objective cough monitoring. Symptom Association Probability (SAP) Analysis characterized the reflux-cough association.

RESULTS

Acid reflux could be a potential mechanism for cough in 45 patients (with either heartburn, high acid exposure or +SAP for acid reflux). Weakly acidic reflux could be a potential mechanism for cough in 24 patients (with either increased oesophageal volume exposure, increased number of weakly acidic reflux or +SAP for weakly acidic reflux). Reflux could not be identified as a potential mechanism for cough in 31 patients.

CONCLUSION

A positive association between cough and weakly acidic reflux was found in a significant subgroup of patients with unexplained chronic cough. Impedance-pH-manometry identified patients in whom cough can be related to reflux that would have been disregarded using the standard diagnostic criteria for acid reflux.

Prevalence and clinical manifestations of gastro-oesophageal reflux-associated chronic cough in the Japanese population

Gastro-oesophageal reflux (GOR) is one of the most common causes of chronic cough in Western countries, responsible for 10 to 40% of cases. In Japan, however, GOR-associated chronic cough (GOR-CC) has been rarely reported and its clinical manifestation including frequency of concomitant reflux laryngitis is poorly known. We have analyzed prevalence and clinical characteristics of patients who were diagnosed as having GOR-CC among adult patients with chronic cough (>or= 8 weeks) who visited our asthma and cough clinic over a period of 19 months. Diagnosis of GOR-CC was based on the response of coughing to a proton-pump inhibitor (lansoprazole) and/or positive results of 24 h ambulatory esophageal pH monitoring. Laryngeal involvement was based on symptoms or objective diagnosis by specialists.GOR-associated chronic cough was diagnosed in 7.1% (8 of 112) of chronic cough patients. In addition to the demographic data which were consistent with the characteristics of patients with GOR-CC in the Western populations, including gender (6 females), age (mean +/- SE, 56.9 +/- 5.8 years), duration of cough (9.9 +/- 3.3 months), lack of gastrointestinal symptoms (3 of 8) and complication with other causes of cough (5 of 8), we found the standard range of body mass index (23.9 +/- 1.5 kg/m2) and high incidence of concomitant reflux laryngitis (5 of 8) in the present 8 patients. Among 4 patients who could stop treatment with temporal resolution of cough, cough recurred in 3 patients, 1 week to 8 months after the discontinuation. In conclusion, GOR-CC is a less frequent cause of chronic cough in Japan than in Western countries. Signs or symptoms of laryngitis may be important as clues to suspicion of GOR-CC.

Chronic cough from the patient's perspective

OBJECTIVE

To identify the factors that patients consider most concerning about their cough.

PATIENTS AND METHODS

All consecutive patients who presented with a complaint of chronic cough between November 1, 2000, and February 28, 2001, were prospectively surveyed for cough-related complaints using an 18-item symptom-complaint questionnaire. We analyzed frequencies of responses and response patterns to specific items on the questionnaire. We also examined whether the responses to individual items related to the patient's age, sex, and duration of cough.

RESULTS

Of the 146 consecutive patients referred for evaluation of chronic cough, 136 were eligible for inclusion in the study. These patients cited feelings of frustration, irritability, or anger (43%), frequent physician visits and testing (41%), and sleep disturbances (38%) as the most prevalent major problems. The responses to individual items on the questionnaire were not related to patients' age, sex, and cough duration. Anxiety about underlying serious illness continued to be a concern for most patients.

CONCLUSIONS

Frustration, anger, or anxiety was the most frequent major problem cited by patients. Frequent physician visits and testing was the unexpected second most frequent major problem. These findings are important because most chronic cough guidelines are based on clinical efficacy and cost-effectiveness considerations rather than on patient satisfaction. Future studies regarding chronic cough evaluation should take into account patient satisfaction and perceived burden of disease as outcome variables.

Acid-sensitive vagal sensory pathways and cough

Acid is an important mediator in the pathogenesis of cough. Inhalation of exogenous acid triggers cough and endogenous acid may contribute to cough in respiratory diseases. Acid directly stimulates vagal bronchopulmonary sensory nerves that regulate the cough reflex. Consistent with their putative role in defence against aspiration and inhaled irritants, Adelta-fibre nociceptors in the large airways are most efficiently stimulated by rapid acidification. In contrast, acid-sensitive properties of the C-fibre nociceptors allow for continuous monitoring of pH which is likely important in inflammation. Acid is also the single most important mediator in the pathogenesis of cough due to gastro-oesophageal reflux (GOR). The cough pathways can be sensitized by the sensory inputs from the oesophagus. This sensitization is likely mediated by a subset of the vagal oesophageal sensory nerves distinguished by discriminative responsiveness to noxious stimuli (nociceptors). The receptors underlying acid sensitivity of vagal sensory nerves are incompletely understood. The role of TRPV1 has been established but the roles of acid-sensing ion channels (ASIC) and other receptors await more definitive investigation. Here, we provide a brief overview of the cough-related acid-sensitive sensory pathways and discuss the mechanisms of acid sensitivity.

Cough throughout life: children, adults and the senile

We review cough from premature birth, mature neonatal life, in childhood and adult life, and in old age. There is a regrettable lack of definitive studies, but many clues in the literature. The cough reflex seems weak in premature infants, but develops with maturity. It is pronounced in childhood, but there seem to be no studies comparing its strength then with that in adulthood. In old age the cough may weaken, as indicated by the prevalence of aspiration pneumonia. These changes are presumably related to the development and degeneration of the afferent and central nervous pathways for cough, which may be reflected in the changes in laryngeal muscle function with age. There is much evidence that age influences the development of the respiratory system in general, and of the immune system which would affect the degree, frequency and clinical issues of cough. Other factors that limit our understanding of the changes in cough with age include the reporting of cough by parents in infants and carers in old age and the use of different diagnostic criteria throughout life. Age-related variation in cough sensitivity seems to be well established, but its quantitation and mechanisms require much further research.

Interpreting the histopathology of chronic cough: a prospective, controlled, comparative study

HYPOTHESIS

Trauma from chronic coughing produces airway inflammation similar to diseases causing cough.

DESIGN

Prospective, cross-sectional, controlled, clinicopathologic correlation study in four groups: group 1, cough from intrapulmonary diseases; group 2, cough from extrapulmonary diseases; group 3, cough that was unexplained; and group 4, nonsmoking, asymptomatic control subjects.

METHODS

Patients with chronic cough underwent a standardized workup including endobronchial biopsies before treatment. Causes were determined by a favorable response to therapy. Bronchial biopsy samples from control subjects were obtained from surgical specimens.

RESULTS

There were 24 adult subjects (13 women and 11 men) with mean cough duration of 8.6 +/- 7.4 years (+/- SD). Thirteen patients had cough due to a specific disease: intrapulmonary diseases in 5 patients, and extrapulmonary diseases in 8 patients. Eleven patients had unexplained cough. Compared to control subjects, there was minimal-to-moderate chronic inflammation in all coughers (p < or = 0.0004), in group 1 (p < or = 0.039), group 2 (p = 0.061), and group 3 (p < or = 0.025) diseases that were not correlated with cough duration. There was no difference in type of inflammation, cough duration, or smoking history between groups, nor were there histologic differences between subjects with explained causes of cough compared with unexplained cough.

CONCLUSIONS

Our findings suggest that airway inflammation associated with chronic cough, assessed on morphologic appearance and inflammatory cell counting in hematoxylin-eosin-prepared samples, may be due to the trauma of coughing, and the inflammation may be similar to that seen with diseases putatively thought to cause chronic cough. Investigators must be cautious when attributing pathogenic importance to observed inflammatory changes in airways of coughing subjects.

Clinical applications of induced sputum

The development of standardized methods for sputum induction has improved the quality and reproducibility of sputum samples. This technique has been used to optimize samples in the investigation of pulmonary tuberculosis and lung cancer, but its clinical application as a noninvasive measure of airway inflammation has highlighted the enormous potential of this technique. Sputum induction has allowed researchers to characterize the inflammatory profiles of a variety of airway diseases including asthma, COPD, and chronic cough. To date, the identification of sputum eosinophilia has the greatest clinical value as this predicts a favorable response to corticosteroids and can therefore guide treatment. In asthma and COPD management, protocols aimed at normalizing the sputum eosinophil count have markedly reduced exacerbations without an overall increase in therapy. Currently, no other noninvasive measure of airway inflammation has demonstrated a benefit in reducing exacerbations. The value of sputum induction and analysis is not restricted to the recognition of sputum eosinophilia but also may be used to direct novel antineutrophilic therapies. Thus, it is time for sputum induction to move from the research laboratory to the clinic.

An empiric integrative approach to the management of cough: ACCP evidence-based clinical practice guidelines

OBJECTIVE

Review the literature to provide a comprehensive approach, including algorithms for the clinician to follow in evaluating and treating the patient with acute, subacute, and chronic cough.

METHODS

We searched MEDLINE (through May 2004) for studies published in the English language since 1980 on human subjects using the medical subject heading terms "cough," "treatment of cough," and "empiric treatment of cough." We selected case series and prospective descriptive clinical trials. We also obtained any references from these studies that were pertinent to the topic.

RESULTS

The relative frequency of the disorders (alone and in combination) that can cause cough as well as the sensitivity and specificity of many but not all diagnostic tests in predicting the cause of cough are known. An effective approach to successfully manage chronic cough is to sequentially evaluate and treat for the common causes of cough using a combination of selected diagnostic tests and empiric therapy. Sequential and additive therapy is often crucial because more than one cause of cough is frequently present.

CONCLUSION

Algorithms that provide a "road map" that the clinician can follow are useful and are presented for acute, subacute, and chronic cough.

Overview of common causes of chronic cough: ACCP evidence-based clinical practice guidelines

OBJECTIVE

To review the literature on the most common causes of chronic cough.

METHODS

MEDLINE was searched (through May 2004) for studies published in the English language since 1980 on human subjects using the medical subject heading terms "cough," "causes of cough," and "etiology of cough." Case series and prospective descriptive clinical trials were selected for review. Also obtained were any references from these studies that were pertinent to the topic

RESULTS

Upper airway cough syndrome (UACS) due to a variety of rhinosinus conditions, previously referred to as postnasal drip syndrome, asthma, nonasthmatic eosinophilic bronchitis (NAEB), and gastroesophageal reflux disease (GERD) are the most common causes of chronic cough. Each of these diagnoses may be present alone or in combination and may be clinically silent apart from the cough itself.

CONCLUSION

In the absence of evidence for the presence of another disorder, an approach focused on detecting the presence of UACS, asthma, NAEB, or GERD, alone or in combination, is likely to have a far higher yield than routinely searching for relatively uncommon or obscure diagnoses.

Effect of d-Pseudoephedrine on Cough Reflex and Its Mode of Action in Guinea Pigs

d-Pseudoephedrine (PSE) is one of the main ingredients of Ephedrae herba. Although PSE is widely applied for patients with a common cold and upper respiratory inflammation as a decongestant, the effects of PSE on cough have never been reported. In this study, we investigated the antitussive effects of intraperitoneal injection of PSE on the cough reflex induced by microinjection of citric acid into the larynx of guinea pigs. PSE decreased the number of cough reflexes dose-dependently (-18.3 +/- 5.0% at 20 mg/kg, P<0.05; -41.1 +/- 7.2% at 60 mg/kg, P<0.01). Furthermore, PSE (60 mg/kg) increased the threshold intensity for inducing fictive cough by electrical micro-stimulation of the nucleus tractus solitarius (+72.7 +/- 8.4%, P<0.01). On the afferent discharge of the superior laryngeal nerve, PSE suppressed the increases of amplitude and frequency when stimulated by citric acid at laryngeal mucosa. These results demonstrate that PSE possesses an antitussive effect that might be derived from both central and peripheral actions.