Laryngeal hypersensitivity in chronic cough

Clinical Parameters of the Speech-Language Pathology Assessment of the Chronic Cough: A Scoping Review

OBJECTIVE

to map the clinical parameters used in the speech-language pathology assessment of the chronic cough.

METHODS

a scoping review was performed to answer the clinical question: "What are the clinical parameters included in the speech-language pathology assessment of patients with chronic cough?" Evidence was searched by electronic and manual search. The electronic search included: MEDLINE, Cochrane Library, EMBASE, Web of Science, SCOPUS, and LILACS. Each database had a specific search strategy. The manual search included Journal of Voice, Chest, and Thorax, Brazilian Library of Theses and Dissertations, Open Grey, and Clinical Trials, in addition to scanning the references of the included studies. The extracted data considered information regarding the publication, sample, assessment, and measures used when assessing chronic cough.

RESULTS

the electronic search found 289 studies; the manual search found 1036 studies; 12 were selected for the present study. The most used assessments were: self-assessment (75%), aerodynamic analysis (66.67%), the perceptual auditory judgment of the voice quality (58.33%), acoustic analysis of the voice (41.67%), cough frequency, and cough threshold (41.67%) and electroglottography (25%).

CONCLUSIONS

the subjective instruments were used more frequently, while specific objective instruments, which are recent, were used less frequently. Complementary assessments such as vocal assessment, have been frequently used, also, with no other parameter. A lack of homogeneity was identified in the speech-language pathology assessment and measures of patients with chronic cough, thus, the comparison among studies and clinical analysis is difficult.

Identifying Practice Gaps Among Otolaryngology Providers for the Treatment of Chronic Cough

Objective

Increasing evidence over the last decade suggests that many cases of unexplained chronic cough (UCC) have a neurogenic etiology, with laryngeal hypersensitivity (LH) being identified as a key mechanism. Official guidelines since 2015 have adopted use of neuromodulators and adjuvant speech therapy as a result, but historically implementation of guidelines is slow. Our survey aimed to investigate gaps in diagnosis and management practices of otolaryngology providers in caring for patients with UCC.

Study Design

Cross-sectional study.

Setting

Survey.

Methods

12-item survey was distributed to 110 otolaryngology practitioners experienced in diagnosis and treatment of chronic cough at a regional otolaryngology continuing education conference. Statistical analysis included Kendall's Tau Rank Correlation to measure the ordinal association between responses to questions, and Fisher's exact test to determine if there were associations between responses and years of career experience.

Results

Forty eligible respondents underwent subsequent analysis. There was no association between frequency of identifying LH as a primary etiology and use of neuromodulators (τ = 0.23, P = .10). However, there was a significant correlation between LH and referrals to speech therapy (τ = 0.27, P = .05). Fisher's exact test did not reveal any significant differences among any responses based on practitioner experience.

Conclusion

Our results indicate a possible disparity in treatment of UCC with neuromodulators and the utilization of speech therapy despite guideline recommendations advocating for neuromodulators with adjuvant speech therapy. Further research with larger sample sizes and more specific inquiries is necessary to elucidate this association and control for any regional differences.

Evaluation and management of chronic cough in adults

Background: Chronic cough (CC), a cough that lasts > 8 weeks, has an overall prevalence of 5-11% in adults, peaking between 60 and 80 years of age. Of the 15% of patients who remain undiagnosed or refractory to treatment, two thirds are women. Objective: The objective was to present an updated evidence-based algorithmic approach for evaluating and managing CC, with emphasis on treatment modalities for refractory CC. Methods: A literature search was conducted of medical literature data bases for guidelines, position papers, systematic reviews, and clinical trials from January 2022 to June 2023, on the evaluation and management of CC. Results: The initial assessment should be limited to a detailed history, physical examination, chest radiograph, spirometry, exhaled nitric oxide, blood eosinophil count, and measurement of cough severity and quality of life by using validated instruments. The top diagnoses to consider are asthma, chronic obstructive pulmonary disease, nonasthmatic eosinophilic bronchitis, gastroesophageal reflux disease, and upper airway cough syndrome. Additional studies are only obtained when red flags are present or the patient fails to respond after avoidance of high-risk factors, e.g., smoking and angiotensin-converting enzyme inhibitors, and 4-6 weeks of empiric treatment for the most likely respiratory and gastrointestinal diseases. When diagnostic tests and/or specific directed treatments fail to control CC, low-dose morphine (preferred), gabapentin, pregabalin, and/or cough control therapy are recommended. Non-narcotic purinergic 2×3 (P2×3) receptor antagonists, gafapixant and campilixant, are currently being studied for CC. Conclusion: For the evaluation and management of patients with CC, clinicians should use an algorithmic approach and identify "red flags," reduce high-risk factors, and use empiric treatment for the five top diagnoses before extensive diagnostic testing. Current treatment for refractory cough is limited to symptomatic management.

Superior Laryngeal Nerve Block Response Rates in 54 Neurogenic Cough Patients

OBJECTIVE

Neurogenic cough related to hypersensitivity of the internal branch of the superior laryngeal nerve (SLN) is often treated with neuromodulating medications, which can cause considerable side effects. An alternative therapy is steroid and local anesthetic injection of the SLN ("SLN block"), initially proposed to benefit those with lateralizing symptoms (tenderness over the thyrohyoid membrane or unilateral cough source). Our objectives are to determine if SLN block produces subjective symptomatic improvements and if repeat injections further improve symptoms, and evaluate clinical factors potentially predictive of response.

METHODS

Retrospective chart review of 54 patients receiving SLN blocks at a tertiary medical academic center from January 2010 to June 2020. Medical history and anticipated predictors of positive response, including stigmata of laryngeal hypersensitivity, were recorded. Outcomes included symptomatic response, number of injections required, and side effects. Response was defined subjectively by asking patients whether the injection was beneficial and objectively by using CSI scores.

RESULTS

Fifty-four patients met the inclusion criteria. Thirty-eight patients (70.4%) endorsed improvement. No variables were identified as positive predictors of response. Thirty-two of the 38 (84.2%) endorsed improvement after one injection. Six of 15 (40%) patients who failed the first injection had positive response to the second. No significant side effects were reported.

CONCLUSION

No localizing symptoms, specific cough features, or aspects of the medical history helped predict response, suggesting that a broader range of patients may be offered the intervention. The majority of patients reported symptomatic improvement and repeat injections may benefit patients with initial nonresponse.

LEVEL OF EVIDENCE

4 Laryngoscope, 133:2647-2653, 2023.

Management of non-pharmacologic therapy for chronic refractory cough: Mechanism, composition, applicable population, and assessment

Chronic cough is common in the clinic and can seriously affect the quality of life of patients. Following the existing guidelines for treatment, refractory chronic cough is defined as a clinical condition in which the cause of the cough remains unclear after comprehensive examination and treatment, or the cause is clear but symptomatic treatment is ineffective. It has been found that non-pharmacologic therapy can effectively improve the quality of life and reduce the frequency of coughing for some patients with refractory chronic cough. Compared with pharmacological therapy, non-pharmacologic therapy has no obvious adverse effects; therefore, non-pharmacologic therapy has good application prospects in the diagnosis and treatment of refractory chronic cough. This paper summarizes the composition, indication, action and mechanism of non-pharmacologic therapy in the diagnosis and treatment of refractory chronic cough and prospects for research on non-pharmacologic therapy.

Standardized Behavioral Treatment Improves Chronic Cough

OBJECTIVES

Neurogenic Laryngeal Hypersensitivity (NLH) refers to a constellation of upper airway symptoms thought to be caused by a disturbance in afferent and/or efferent neural pathways creating an exaggerated hypersensitive laryngeal response. There is evidence to support behavioral therapy as treatment for improving symptoms from laryngeal motor dysfunction to sensory disturbance. This study aims to determine if there is significant symptomatic improvement in patients with NLH who received non-pharmacologic behavioral treatment performed by trained SLPs.

STUDY DESIGN

A retrospective review.

METHODS

A review of all patients with NLH from 2017 to 2020 was performed at a tertiary care voice and swallowing center. Subjects with persistent symptoms despite maximal medical management were considered for inclusion. Newcastle Laryngeal Hypersensitivity Questionnaire (NLHQ) was completed by patients before and after undergoing therapy by one of three trained SLPs. Posttherapy improvement was determined by utilizing the NLHQ's minimal clinically important difference of 1.7 points.

RESULTS

A total of 81 patients were included in this study. Study participants included 61 women and 20 men with an average age of 60.64±14.05 years. There was a statistically significant difference between the pre and post therapy scores amongst all patients when treated by each individual SLP and all three SLPs combined (P < 0.008). There was a clinically significant change in 66% of all patients, 76% of which presented with abnormal NLHQ scores, and 14% who presented with normal NLHQ scores.

CONCLUSIONS

A standardized behavioral treatment protocol for patients with symptoms consistent with NLH is effective in improving symptoms in a large majority of patients. When following a standardized protocol SLPs can obtain similar results for their patients.

Acute, Recurrent, and Chronic Laryngopharyngeal Reflux: The IFOS Classification

OBJECTIVE

To investigate the clinical patterns and disease evolution of laryngopharyngeal reflux (LPR) patients.

METHODS

Patients with LPR diagnosed by hypopharyngeal-esophageal impedance-pH monitoring were prospectively followed in three medical centers. Symptoms and findings were assessed with reflux symptom score (RSS) and reflux sign assessment (RSA). Patients were treated with 3-to 9-month diet and combination of proton pump inhibitors, alginate or magaldrate. Patients were followed for 3 years to determine the clinical evolution of symptoms over time. LPR that did not recur was defined as acute. Recurrent LPR consisted of reflux with one or several recurrences yearly despite successful treatment. Chronic LPR was reflux with a chronic course of symptoms. Predictive indicators of clinical evolution were investigated.

RESULTS

One hundred forty patients and 82 healthy individuals completed the evaluations. Among patients, 41 (29.3%), 57 (40.7%), and 42 (30.0%) had acute, recurrent, or chronic LPR respectively. Baseline quality of life-RSS (QoL-RSS) and RSS total scores were significantly higher in chronic LPR patients. The post-treatment decrease of QoL-RSS and RSS of acute LPR patients were significantly faster as compared to recurrent and chronic patients. QoL-RSS >5 reported adequate sensitivity (94.2) and specificity (75.3). QoL-RSS thresholds defined acute (QoL-RSS = 6-25), recurrent (QoL-RSS = 26-38), and chronic (QoL-RSS > 38) LPR.

CONCLUSION

Baseline QoL-RSS may predict the clinical course of LPR patients: acute, recurrent, or chronic. A novel classification system that groups patients according to the longevity, severity, and therapeutic response of symptoms was proposed: the International Federation of Otorhinolaryngological Societies Classification of LPR.

LEVEL OF EVIDENCE

3 Laryngoscope, 133:1073-1080, 2023.

Laryngopharyngeal Reflux: Evolution and Predictive Value of Symptoms and pH-Impedance Features on Clinical Evolution

OBJECTIVES

To investigate the features of patients with laryngopharyngeal reflux (LPR) who did not respond to medical treatment.

STUDY DESIGN

Prospective uncontrolled study.

SETTING

Multicenter study.

METHODS

Patients with LPR at 24-hour HEMII-pH monitoring (hypopharyngeal-esophageal multichannel intraluminal impedance-pH) were prospectively recruited from 3 European university centers. Patients were treated with 3- to 6-month medication (proton pump inhibitor and alginate) and categorized as mild to moderate responders, high responders, or nonresponders according to Reflux Symptom Score (RSS) changes at 6 months posttreatment. The predictive value of the following outcomes was studied: epidemiologic data, HEMII-pH, gastrointestinal endoscopy findings, baseline RSS and Reflux Sign Assessment, and early therapeutic response (6-week RSS).

RESULTS

A total of 148 patients completed the evaluations, accounting for 40 mild to moderate responders (20%-60% RSS changes), 76 high responders (>60% RSS changes), and 32 nonresponders. Nonresponders presented more often with hiatal hernia and lower esophageal sphincter insufficiency when compared with mild to moderate and high responders (P = .032). Baseline otolaryngologic, digestive, and respiratory RSS and the number of pharyngeal reflux events at the HEMII-pH were predictive of the 6-month therapeutic response (P < .05). The early therapeutic response (6 weeks posttreatment) was predictive of the 6-month treatment response.

CONCLUSION

Hiatal hernia and baseline and 6-week RSS were the most predictive indicators of therapeutic effectiveness in patients with LPR.

Burden and impact of chronic cough in UK primary care: a dataset analysis

OBJECTIVE

Chronic cough (CC) is a debilitating respiratory symptom, now increasingly recognised as a discrete disease entity. This study evaluated the burden of CC in a primary care setting.

DESIGN

Cross-sectional, retrospective cohort study.

SETTING

Discover dataset from North West London, which links coded data from primary and secondary care. The index date depicted CC persisting for ≥8 weeks and was taken as a surrogate for date of CC diagnosis.

PARTICIPANTS

Data were extracted for individuals aged ≥18 years with a cough persisting ≥8 weeks or cough remedy prescription, between Jan 2015 and Sep 2019.

MAIN OUTCOME MEASURES

Demographic characteristics, comorbidities and service utilisation cost, including investigations performed and treatments prescribed were determined.

RESULTS

CC was identified in 43 453 patients from a total cohort of 2 109 430 (2%). Median (IQR) age was 64 years (41-87). Among the cohort, 31% had no recorded comorbidities, 26% had been given a diagnosis of asthma, 17% chronic obstructive pulmonary disease, 12% rhinitis and 15% reflux. Prevalence of CC was greater in women (57%) and highest in the 65-74 year age range. There was an increase in the number of all investigations performed in the 12 months before and after the index date of CC diagnosis, and in particular for primary care chest X-ray and spirometry which increased from 6535 to 12 880 and from 5791 to 8720, respectively. This was accompanied by an increase in CC-associated healthcare utilisation costs.

CONCLUSION

One-third of individuals had CC in the absence of associated comorbidities, highlighting the importance of recognising CC as a condition in its own right. Overall outpatient costs increased in the year after the CC index date for all comorbidities, but varied significantly with age. Linked primary-care datasets may enable earlier detection of individuals with CC for specialist clinic referral and targeted treatment.

Laryngeal hypersensitivity and abnormal cough response during mannitol bronchoprovocation challenge

BACKGROUND AND OBJECTIVE

Inhalational challenge with dry mannitol powder may potentially induce cough by two mechanisms: airway bronchoconstriction or laryngeal irritation. This prospective observational study investigated laryngeal and bronchial components of cough induced by mannitol challenge.

METHODS

We recruited consecutive patients referred for clinical mannitol challenge. The Newcastle Laryngeal Hypersensitivity Questionnaire (LHQ) was administered. Throughout testing, coughs were audio-recorded to derive a cough frequency index per time and dose of mannitol. Relationships between cough indices, laryngeal hypersensitivity and bronchial hyperresponsiveness (BHR) were examined. Participants were classified by cough characteristics with k-means cluster analysis.

RESULTS

Of 90 patients who underwent challenge, 83 completed both the questionnaire and challenge. Cough frequency was greater in patients with abnormal laryngeal hypersensitivity (p = 0.042), but not in those with BHR. There was a moderate negative correlation between coughs per minute and laryngeal hypersensitivity score (r = -0.315, p = 0.004), with lower LHQ scores being abnormal. Cluster analysis identified an older, female-predominant cluster with higher cough frequency and laryngeal hypersensitivity, and a younger, gender-balanced cluster with lower cough frequency and normal laryngeal sensitivity.

CONCLUSION

Cough frequency during mannitol challenge in our cohort reflected laryngeal hypersensitivity rather than BHR. Laryngeal hypersensitivity was more often present among older female patients. With the incorporation of cough indices, mannitol challenge may be useful to test for laryngeal hypersensitivity as well as BHR.

Revised Korean Cough Guidelines, 2020: Recommendations and Summary Statements

Cough is the most common respiratory symptom that can have various causes. It is a major clinical problem that can reduce a patient's quality of life. Thus, clinical guidelines for the treatment of cough were established in 2014 by the cough guideline committee under the Korean Academy of Tuberculosis and Respiratory Diseases. From October 2018 to July 2020, cough guidelines were revised by members of the committee based on the first guidelines. The purpose of these guidelines is to help clinicians efficiently diagnose and treat patients with cough. This article highlights the recommendations and summary of the revised Korean cough guidelines. It includes a revised algorithm for the evaluation of acute, subacute, and chronic cough. For a chronic cough, upper airway cough syndrome (UACS), cough variant asthma (CVA), and gastroesophageal reflux disease (GERD) should be considered in differential diagnoses. If UACS is suspected, first-generation antihistamines and nasal decongestants can be used empirically. In cases with CVA, inhaled corticosteroids are recommended to improve cough. In patients with suspected chronic cough due to symptomatic GERD, proton pump inhibitors are recommended. Chronic bronchitis, bronchiectasis, bronchiolitis, lung cancer, aspiration, intake of angiotensin-converting enzyme inhibitor, intake of dipeptidyl peptidase-4 inhibitor, habitual cough, psychogenic cough, interstitial lung disease, environmental and occupational factors, tuberculosis, obstructive sleep apnea, peritoneal dialysis, and unexplained cough can also be considered as causes of a chronic cough. Chronic cough due to laryngeal dysfunction syndrome has been newly added to the guidelines.

Laryngopharyngeal reflux: The microbiota theory

Laryngopharyngeal reflux (LPR) is a prevalent disease associated with non-specific symptoms and findings. Many gray areas persist in the pathogenesis of LPR, the diagnosis and the treatment. Symptoms are poorly correlated with fiberoptic signs or hypopharyngeal-esophageal multichannel intraluminal impedance-pH monitoring findings. The therapeutic response remains uncertain with some resistant patients to medical or surgical treatment. The development of LPR-symptoms and findings may be related to the refluxate of a myriad of gastroduodenal enzymes, which may modify the laryngopharyngeal and oral microbiome leading to mucosa maintenance and recovery impairments. The diet of patient is important because it may impact the microbiome composition and some foods are known to increase the number of hypopharyngeal reflux events. The number of hypopharyngeal reflux events may be increased by autonomic nerve dysfunction that may have an important role in the persistence of LPR-symptoms.

Evidence of Possible Irritable Larynx Syndrome in Obstructive Sleep Apnea: An Epidemiologic Approach

OBJECTIVE

"Irritable larynx syndrome" (ILS) often refers to a constellation of laryngeal-based symptoms including chronic cough (CC), diurnal dyspnea, and dysphonia. In patients with OSA, we examined: (1) the frequency, severity, comorbidity, risks and triggers of each problem, (2) whether these symptoms were compatible with stereotypic ILS and (3) the role of CPAP in their expression.

STUDY DESIGN

Cross-sectional, descriptive epidemiology study.

SETTING

Sleep-Wake Center at University of Utah Health Care, Salt Lake City, UT.

SUBJECTS AND METHODS

Ninety-four individuals with OSA (53 men, 41 women; mean age 54.7 ± 12.8 yrs.) underwent an extensive telephone interview that addressed study objectives.

RESULTS

Long-term CC, daytime breathing and voice problems were common, especially among women despite less severe OSA. Women, more than men, reported all three chronic conditions alone or in combination: CC (44% vs 11.3%), diurnal dyspnea (41.5% vs 13.2%) and voice disorders (41.5% vs 13.2%). Symptoms were not associated with age, BMI or Apnea Hypopnea Index after adjusting for sex. Although evidence supporting stereotypic ILS symptomatology was inconsistent, those participants with a voice disorder were 3.3 (95% CI = 1.8-6.0) times more likely to report CC and 2.4 (95% CI = 1.3-4.4) times more likely to experience diurnal dyspnea. Esophageal reflux, post-nasal drip, and frequent sinus infections were significantly associated with all three conditions. Triggers that provoked or made symptoms worse varied by condition and sex. Nightly, humidified CPAP use was associated with fewer symptoms overall and improved quality of life.

CONCLUSIONS

Symptoms suggestive of possible ILS are common in OSA, especially among women, and lessened by nightly CPAP use.

Assessing laryngeal function and hypersensitivity

The larynx is one of the most highly innervated organs in humans, adapted to simultaneously deliver several key respiratory functions including airway protection, swallowing and phonation. In some individuals the larynx can adopt a state that could be considered 'dysfunctional' or maladaptive; resulting in or contributing to a range of clinical disorders such as chronic refractory cough, inducible laryngeal obstruction (previously termed paradoxical vocal fold movement or vocal cord dysfunction), muscle tension dysphonia and globus pharyngeus. These disorders appear to display significant overlap in clinical symptomology and in many cases have features of concomitant or allied sensory dysfunction; often described as laryngeal hypersensitivity. The recognition and accurate assessment of both laryngeal dysfunction±hypersensitivity is important to ensure accurate diagnosis and effective delivery of targeted treatment and therapeutic monitoring. Accordingly, there is increasing in the methodologies proposed to assess laryngeal function. These range from simple questionnaires to targeted investigation(s), assessing both sensory function and the laryngeal motor response, under both resting and provoked situations. This review provides a brief overview of the current state of knowledge in the field of laryngeal dysfunction and hypersensitivity assessment.

Analysis of the volume of fluid (VOF) method for the simulation of the mucus clearance process with CFD

The clearance of mucus through coughing is a complex, multiphase process, which is affected principally by mucus viscosity and airflow velocity; however, it is also critically affected by the thickness of the two layers of mucus-the serous and gel layers-and oscillation level. The present study examines the effects of the latter parameters more closely. To do so, the mucus clearance process is simulated with a transient 3D volume of fluid (VOF) multiphase model in ANSYS Fluent. The model includes mucus' bilayer properties and a wide range of boundary conditions were tested. The model was analysed in both a straight tube and a realistic trachea. Ultimately, the model was able to both capture air-mucus interface wave evolution and predict the overall behaviour of the clearance process. The results were consistent with experimental clearance data and numerical airflow simulations, which indicates our methodology is appropriate for future studies. Ultimately, the mere presence of the serous layer was found to increase mucus clearance by more than 15 percent. An oscillating flow enhanced clearance by up to 5 percent. Interestingly, interface wave steepness was found to be inversely correlated with mucus thickness, but directly with mucus velocity, which suggests it will be an interesting parameter for further study.

Cough in exercise and athletes

In the general population, particularly in individuals with asthma, cough is a common symptom, often reported after exertion, although regular exercise may be associated with a reduction in the prevalence of cough. In athletes, exercise-induced cough is also a particularly frequent symptom. The main etiologies of cough in athletes are somewhat similar to non-athletes, including asthma/airway hyperresponsiveness, upper airways disorders such as allergic or non-allergic rhinitis, and exercise-induced laryngeal obstruction, although these conditions are more frequently observed in athletes. In these last, this symptom can also be related to the high ventilation and heat exchange experienced during exercise, particularly during exposure to cold/dry air or pollutants. However, gastroesophageal reflux, a common cause of cough in the general population, despite being highly prevalent in athletes, has not been reported as a main cause of cough in athletes. Cough may impair quality of life, sleep and exercise performance in the general population and probably also in athletes, although there are few data on this. The causes of cough should be documented through a systematic evaluation, the treatment adapted according to identified or most probable cough etiology and pattern of presentation, while respecting sports anti-doping regulations. More research is needed on exercise-induced persistent cough in the athlete to determine its pathophysiology, optimal management and consequences.

Comorbid "treatable traits" in difficult asthma: Current evidence and clinical evaluation

The care of patients with difficult-to-control asthma ("difficult asthma") is challenging and costly. Despite high-intensity asthma treatment, these patients experience poor asthma control and face the greatest risk of asthma morbidity and mortality. Poor asthma control is often driven by severe asthma biology, which has appropriately been the focus of intense research and phenotype-driven therapies. However, it is increasingly apparent that extra-pulmonary comorbidities also contribute substantially to poor asthma control and a heightened disease burden. These comorbidities have been proposed as "treatable traits" in chronic airways disease, adding impetus to their evaluation and management in difficult asthma. In this review, eight major asthma-related comorbidities are discussed: rhinitis, chronic rhinosinusitis, gastroesophageal reflux, obstructive sleep apnoea, vocal cord dysfunction, obesity, dysfunctional breathing and anxiety/depression. We describe the prevalence, impact and treatment effects of these comorbidities in the difficult asthma population, emphasizing gaps in the current literature. We examine the associations between individual comorbidities and highlight the potential for comorbidity clusters to exert combined effects on asthma outcomes. We conclude by outlining a pragmatic clinical approach to assess comorbidities in difficult asthma.

Glottis effects on the cough clearance process simulated with a CFD dynamic mesh and Eulerian wall film model

In this study, we have reproduced the cough clearance process with an Eulerian wall film model. The simulated domain is based on realistic geometry from the literature, which has been improved by adding the glottis and epiglottis. The vocal fold movement has been included due to the dynamic mesh method, considering different abduction and adduction angles and velocities. The proposed methodology captures the deformation of the flexible tissue, considers non-Newtonian properties for the mucus, and enables us to reproduce a single cough or a cough epoch. The cough efficiency (CE) has been used to quantify the overall performance of the cough, considering many different boundary conditions, for the analysis of the glottis effect. It was observed that a viscous shear force is the main mechanism in the cough clearance process, while the glottis closure time and the epiglottis position do not have a significant effect on the CE. The cough assistance devices improve the CE, and the enhancement rate grows logarithmically with the operating pressure. The cough can achieve an effective mucus clearance process, even with a fixed glottis. Nevertheless, the glottis closure substantially improves the CE results.

Laryngeal Dysfunction: Assessment and Management for the Clinician

The larynx is one of the most highly innervated organs in humans and serves a number of vitally important, complex, and highly evolved biological functions. On a day-to-day basis, the larynx functions autonomously, addressing several roles including airway protection, swallowing, and phonation. In some situations the larynx appears to adopt a functional state that could be considered maladaptive or "dysfunctional." This laryngeal dysfunction can underpin and account for a number of respiratory symptoms that otherwise appear incongruous with a clinical disease state and/or contribute to the development of symptoms that appear "refractory" to treatment. These include conditions associated with a heightened tendency for inappropriate laryngeal closure (e.g., inducible laryngeal obstruction), voice disturbance, and chronic cough. Recognition of laryngeal dysfunction is important to deliver targeted treatment and failure to recognize the condition can lead to repeated use of inappropriate treatment. Diagnosis is not straightforward, however, and many patients appear to present with symptoms attributable to laryngeal dysfunction, but in whom the diagnosis has been overlooked in clinical work-up for some time. This review provides an overview of the current state of knowledge in the field of laryngeal dysfunction, with a focus on pragmatic clinical assessment and management.

Cough in exercise and athletes

Cough is the most common respiratory symptom reported by athletes and can significantly impact on health status, ability to train and athletic performance. The presence of cough in an athlete is typically taken to indicate exercise-induced bronchoconstriction (EIB), yet in many athletes with chronic cough there is no objective evidence of airway hyper-responsiveness (AHR) or heightened airway inflammation. Moreover, cough in athletes often fails to respond to a therapeutic asthma strategy, thus further work is urgently needed to progress our understanding of the pathophysiology of exercise-associated cough in this unique population. This article provides an overview of the current state of knowledge of exercise-associated cough in athletes. The article summarises our understanding of pathophysiological basis of cough in this context and provides a pragmatic clinical approach to this problem.

Somatic cough syndrome or psychogenic cough-what is the difference?

The term psychogenic cough has been used to describe cough without obvious medical etiology, which is refractory to medical management and considered to have a psychiatric or psychological basis. However there are limitations in the research into psychogenic cough with limited empirical data on how to define the condition or differentially diagnose it from other forms of chronic cough. The term somatic cough syndrome was introduced by the American College of Chest physicians in 2015 during their revision of the 2006 guideline on psychogenic cough. Psychomorbidity can be present in chronic cough arising from a variety of etiologies and can impact on symptom perception and clinical management of the condition. Psychological symptoms can also improve after effective treatment of the chronic cough. The recently published American College of Chest Physicians cough guidelines recommended replacing the term psychogenic cough with the term somatic cough syndrome in order to be consistent with the Diagnostic Statistical Manual of Mental Disorders, 5^th edition (DSM-5) where the term psychogenic is no longer used. This paper outlines the current evidence regarding psychogenic cough, proposes a model for conceptualising psychological issues in chronic cough and discusses strategies for clinical management of psychological issues in patients with chronic cough.

Advances in mechanisms and management of chronic cough: The Ninth London International Cough Symposium 2016

At the Ninth London International Cough Symposium held in June 2016, advances in chronic cough were presented. Chronic cough has been labelled as a cough hypersensitivity syndrome (CHS) with neuroinflammatory mechanisms likely to be the underlying mechanisms. The concept is that there is a stage of peripheral sensitisation induced by inflammatory factors setting up the scene for a central component that can be visualised by functional magnetic resonance imaging. There has also been progress in assessing CHS patients in the clinic in terms of measuring cough, with an increasing interest in assessing different types of cough associated with respiratory diseases such as asthma, COPD, bronchiectasis and pulmonary fibrosis. There is an emerging area of new antitussives in the form of neuromodulators. These advances have been paralleled by improvements in the management of patients with chronic cough. However, more work is needed but the future looks promising.

Evidence-based Evaluation and Management of Chronic Cough

Chronic cough is common and has a significant impact on the wellbeing of patients and the use and cost of health care services. Traditionally the approach to chronic cough in patients who are nonsmokers and are not taking an angiotensin-converting enzyme inhibitor has focused on the diagnosis and management of the upper airway cough syndrome, asthma, and reflux disease. The evaluation of patients with chronic cough frequently involves trials of empiric therapy for these 3 conditions. Chronic cough may be perpetuated by abnormalities of the cough reflex and sensitization of its afferent and central components.