Long-term safety of nebulized lidocaine for adults with difficult-to-control chronic cough: a case series

The Therapeutic Landscape in Chronic Cough

In recent years, there has been a substantial increase in the development of antitussive therapies and the first new therapy, gefapixant has been licenced in Europe. This review describes current unlicenced treatments for chronic cough and details treatments currently in development for refractory chronic cough and cough in idiopathic pulmonary fibrosis, as well as compounds previously explored.

Mechanisms and management of cough in interstitial lung disease

INTRODUCTION

Many patients with interstitial lung diseases (ILDs), especially fibrotic ILDs, experience chronic cough. It negatively impacts both physical and psychological well-being. Effective treatment options are limited.

AREAS COVERED

The pathophysiology of chronic cough in IPF is complex and involves multiple mechanisms, including mechanical distortion of airways, parenchyma, and nerve fibers. The pathophysiology of cough in other fibrosing ILDs is poorly understood and involves various pathways. The purpose of this review is to highlight mechanisms of chronic cough and to present therapeutic evidence for its management in the most commonly occurring diffuse fibrosing lung diseases including idiopathic pulmonary fibrosis (IPF), connective tissue disease-related interstitial lung disease (CTD-ILD), sarcoidosis-related ILD (Sc-ILD), chronic hypersensitivity pneumonitis-related ILD (CHP-ILD), and post-COVID-19-related interstitial lung disease (PC-ILD).

EXPERT OPINION

This review guides the management of chronic cough in fibrosing ILDs. In this era of precision medicine, chronic cough management should be individualized in each interstitial lung disease.

Approach to post COVID-19 persistent cough: A narrative review

A large proportion of patients who completely recovered from acute coronavirus disease 2019 (COVID-19) infection later continued to experience symptoms even after recovery, irrespective of the severity of the disease. Various terms with varying duration were used for those who had persistent symptoms, of which cough was the most common. We systematically searched the published literature concerning post-COVID-19 cough, its prevalence, and the potential ways to reduce it in clinical practice. The aim of this review was to provide an overview of existing literature concerning post-COVID-19 cough. Literature shows that augmented cough reflex sensitivity is responsible for persistent cough after acute viral upper respiratory infection (URI). Overall, the heightened cough reflex associated with SARSCoV2 induces neurotropism, neuroinflammation, and neuroimmunomodulation via the vagal sensory nerves. Therapies for post-COVID-19 cough aim at the suppression of cough reflex. For a patient who does not respond to early symptomatic treatment, Inhaled corticosteroids can be given a trial to suppress airway inflammation. More trials of novel cough therapies in patients with post-COVID-19 cough using various outcome measures need to be studied in future research. Several agents are currently available for symptomatic relief. However, non-response or refractory cough continues to preclude adequate symptom relief.

Clinical effects and pharmacokinetics of nebulized lidocaine in healthy horses

Background

Nebulized lidocaine appears promising as a novel corticosteroid-sparing therapeutic for equine asthma, but its safety and pharmacokinetic behavior have yet to be confirmed.

Objective

To describe the effect of nebulized lidocaine on upper airway sensitivity, lung mechanics, and lower respiratory cellular response of healthy horses, as well as delivery of lidocaine to lower airways, and its subsequent absorption, clearance, and duration of detectability.

Animals

Six healthy university- and client-owned horses with normal physical examination and serum amyloid A, and no history of respiratory disease within 6 months.

Methods

Prospective, descriptive study evaluating the immediate effects of 1 mg/kg 4% preservative-free lidocaine following nebulization with the Flexineb^®. Prior to and following nebulization, horses were assessed using upper airway endoscopy, bronchoalveolar lavage, and pulmonary function testing with esophageal balloon/pneumotachography and histamine bronchoprovocation. Additionally, blood and urine were collected at predetermined times following single-dose intravenous and nebulized lidocaine administration for pharmacokinetic analysis.

Results

Upper airway sensitivity was unchanged following lidocaine nebulization, and no laryngospasm or excessive salivation was noted. Lidocaine nebulization (1 mg/kg) resulted in a mean epithelial lining fluid concentration of 9.63 ± 5.05 μg/mL, and a bioavailability of 29.7 ± 7.76%. Lidocaine concentrations were higher in epithelial lining fluid than in systemic circulation (C_max 149.23 ± 78.74 μg/L, C_ELF:C_maxplasma 64.4, range 26.5–136.8). Serum and urine lidocaine levels remained detectable for 24 and 48 h, respectively, following nebulization of a single dose. Baseline spirometry, lung resistance and dynamic compliance, remained normal following lidocaine nebulization, with resistance decreasing post-nebulization. Compared to the pre-nebulization group, two additional horses were hyperresponsive following lidocaine nebulization. There was a significant increase in mean airway responsiveness post-lidocaine nebulization, based on lung resistance, but not dynamic compliance. One horse had BAL cytology consistent with airway inflammation both before and after lidocaine treatment.

Conclusions

Nebulized lidocaine was not associated with adverse effects on upper airway sensitivity or BAL cytology. While baseline lung resistance was unchanged, increased airway reactivity to histamine bronchoprovocation in the absence of clinical signs was seen in some horses following nebulization. Further research is necessary to evaluate drug delivery, adverse events, and efficacy in asthmatic horses.

Indian Guidelines on Nebulization Therapy

Inhalational therapy, today, happens to be the mainstay of treatment in obstructive airway diseases (OADs), such as asthma, chronic obstructive pulmonary disease (COPD), and is also in the present, used in a variety of other pulmonary and even non-pulmonary disorders. Hand-held inhalation devices may often be difficult to use, particularly for children, elderly, debilitated or distressed patients. Nebulization therapy emerges as a good option in these cases besides being useful in the home care, emergency room and critical care settings. With so many advancements taking place in nebulizer technology; availability of a plethora of drug formulations for its use, and the widening scope of this therapy; medical practitioners, respiratory therapists, and other health care personnel face the challenge of choosing appropriate inhalation devices and drug formulations, besides their rational application and use in different clinical situations. Adequate maintenance of nebulizer equipment including their disinfection and storage are the other relevant issues requiring guidance. Injudicious and improper use of nebulizers and their poor maintenance can sometimes lead to serious health hazards, nosocomial infections, transmission of infection, and other adverse outcomes. Thus, it is imperative to have a proper national guideline on nebulization practices to bridge the knowledge gaps amongst various health care personnel involved in this practice. It will also serve as an educational and scientific resource for healthcare professionals, as well as promote future research by identifying neglected and ignored areas in this field. Such comprehensive guidelines on this subject have not been available in the country and the only available proper international guidelines were released in 1997 which have not been updated for a noticeably long period of over two decades, though many changes and advancements have taken place in this technology in the recent past. Much of nebulization practices in the present may not be evidence-based and even some of these, the way they are currently used, may be ineffective or even harmful. Recognizing the knowledge deficit and paucity of guidelines on the usage of nebulizers in various settings such as inpatient, out-patient, emergency room, critical care, and domiciliary use in India in a wide variety of indications to standardize nebulization practices and to address many other related issues; National College of Chest Physicians (India), commissioned a National task force consisting of eminent experts in the field of Pulmonary Medicine from different backgrounds and different parts of the country to review the available evidence from the medical literature on the scientific principles and clinical practices of nebulization therapy and to formulate evidence-based guidelines on it. The guideline is based on all possible literature that could be explored with the best available evidence and incorporating expert opinions. To support the guideline with high-quality evidence, a systematic search of the electronic databases was performed to identify the relevant studies, position papers, consensus reports, and recommendations published. Rating of the level of the quality of evidence and the strength of recommendation was done using the GRADE system. Six topics were identified, each given to one group of experts comprising of advisors, chairpersons, convenor and members, and such six groups (A-F) were formed and the consensus recommendations of each group was included as a section in the guidelines (Sections I to VI). The topics included were: A. Introduction, basic principles and technical aspects of nebulization, types of equipment, their choice, use, and maintenance B. Nebulization therapy in obstructive airway diseases C. Nebulization therapy in the intensive care unit D. Use of various drugs (other than bronchodilators and inhaled corticosteroids) by nebulized route and miscellaneous uses of nebulization therapy E. Domiciliary/Home/Maintenance nebulization therapy; public & health care workers education, and F. Nebulization therapy in COVID-19 pandemic and in patients of other contagious viral respiratory infections (included later considering the crisis created due to COVID-19 pandemic). Various issues in different sections have been discussed in the form of questions, followed by point-wise evidence statements based on the existing knowledge, and recommendations have been formulated.

Sufentanil EC50 for endotracheal intubation with aerosol inhalation of carbonated lidocaine by ultrasonic atomizer

BACKGROUND

Nebulized lidocaine reduced stress response for endotracheal intubation. However, the impact of novel lidocaine aerosol inhalation for intubation by ultrasonic atomizer was unclear. Hence, we designed aerosol inhalation of lidocaine by ultrasonic atomizer, to seek whether the dosage of sufentanil for intubation could be less or not.

METHODS

Intravenous injection of sufentanil started at 0.5 μg/kg, and sufentanil dosage was increased/decreased (step-size 0.05 μg/kg for sufentanil) using Dixon's up and down method. The observation was terminated after 8 reflexes.

RESULTS

The EC50 and EC95 of sufentanil with lidocaine by ultrasonic atomizer for intubation were found to be 0.232 μg/kg (95% CI: 0.187-0.270 μg/kg) and 0.447 μg/kg (95% CI: 0.364-0.703 μg/kg). 55.88% out of 34 patients showed hemodynamic index change < 20% of baseline during intubation.

CONCLUSION

Aerosol inhalation of lidocaine by ultrasonic atomizer reduced the dosage of sufentanil for endotracheal intubation. Lidocaine inhalation by ultrasonic atomizer for airway anesthesia with minimal dosage of sufentanil could be recommended, particularly in patients who need more stable hemodynamic changes or spontaneous respiration.

TRIAL REGISTRATION

Chinese Registry of Central Trial, ChiCTR-IOR-17014198 . Registered 28 December 2017.

The Prospect for Potent Sodium Voltage-Gated Channel Blockers to Relieve an Excessive Cough

An excessive, irritable, productive or non-productive coughing associated with airway inflammation belongs to pathological cough. Increased activation of airway vagal nociceptors in pathological conditions results from dysregulation of the neural pathway that controls cough. A variety of mediators associated with airway inflammation overstimulate these vagal airway fibers including C-fibers leading to hypersensitivity and hyperreactivity. Because current antitussives have limited efficacy and unwanted side effects there is a continual demand for the development of a novel more effective antitussives for a new efficacious and safe cough treatment. Therefore, inhibiting the activity of these vagal C-fibers represents a rational approach to the development of effective antitussive drugs. This may be achieved by blocking inflammatory mediator receptors or by blocking the generator potential associated with the specific ion channels. Because voltage-gated sodium channels (NaVs) are absolutely required for action potentials initiation and conduction irrespective of the stimulus, NaVs become a promising neural target. There is evidence that NaV1.7, 1.8 and 1.9 subtypes are predominantly expressed in airway cough-triggering nerves. The advantage of blocking these NaVs is suppressing C-fiber irrespective to stimuli, but the disadvantage is that by suppressing the nerves is may also block beneficial sensations and neuronal reflex behavior. The concept is that new antitussive drugs would have the benefit of targeting peripheral airway nociceptors without inhibiting the protective cough reflex.

A Randomized Controlled Trial to Assess the Effect of Lidocaine Administered via Throat Spray and Nebulization in Patients with Refractory Chronic Cough

BACKGROUND

Refractory chronic cough (RCC) is a debilitating condition for which there are no licensed treatments. Lidocaine is a nonselective inhibitor of voltage-gated sodium channels with potential antitussive effects, but randomized placebo-controlled studies evaluating its efficacy in RCC are lacking.

OBJECTIVE

To investigate the efficacy of nebulized lidocaine and lidocaine throat spray versus matched placebos in RCC.

METHODS

This was a randomized, double-blind, double-dummy, placebo-controlled, 3-way crossover study, comparing the effect of single doses of nebulized lidocaine with lidocaine delivered by a throat spray and matched placebo. The primary end point was cough frequency over the 10 hours following treatment. Secondary end points were visual analog scale scores for urge-to-cough and cough severity; an exploratory analysis evaluated hourly cough rates up to 5 hours after treatment.

RESULTS

Twenty-six subjects with RCC were recruited (22 females; mean age, 53.5 ± 12.1 years; FEV₁ %predicted, 105.2 ± 16.8 L; forced vital capacity %predicted, 112.4 ± 18 L). Lidocaine throat spray, but not nebulized lidocaine, significantly reduced 10-hour cough frequency as compared with placebo (throat spray, 22.6 coughs/h; nebulization, 26.9 coughs/h; and placebos, 27.6 coughs/h; P = .04,). Lidocaine throat spray showed the greatest effect on cough compared with placebo in the first hour after administration (31.7 coughs/h vs 74.2 coughs/h; P = .004). Both nebulizer and spray treatments significantly alleviated urge-to-cough and cough severity visual analog scale scores compared with placebo (P < .05). There were no serious adverse events associated with lidocaine therapy.

CONCLUSIONS

Lidocaine throat spray was effective in reducing cough frequency in patients with RCC. Voltage-gated sodium channel inhibitors applied to pharynx have potential as therapies for RCC.

Management of chronic refractory cough in adults

Cough is a common respiratory symptom that is considered to be chronic when it lasts more than eight weeks. When severe, chronic cough may significantly impact an individual's quality of life, and such patients are frequently referred for specialist evaluation. Current international guidelines provide algorithms for the management of chronic cough: in most cases, treatment of the underlying disease is sufficient to improve or resolve cough symptoms. Severe chronic cough may significantly affect patients' quality of life and necessitate frequent referral for specialist evaluations. In this narrative review, we summarize non-pharmacologic and pharmacologic management of adult patients with chronic cough of known cause that persists after proper treatment (chronic refractory cough, CRC) or chronic cough of unknown cause in adult patients. If chronic cough persists even after treatment of the underlying disease, or if the chronic cough is not attributable to any cause, then a symptomatic approach with neuromodulators may be considered, with gabapentin as the first choice, and opioids or macrolides as alternatives. Speech pathology treatment and/or neuromodulators should be discussed with patients and alternative options carefully considered, taking into account risk/benefit. Novel promising drugs are under investigation (e.g. P2×3 inhibitors), but additional studies are needed in this field. Speech pathology can be combined with a neuromodulator to give an enhanced treatment response of longer duration suggesting that non-pharmacologic treatment may play a key role in the management of CRC.

Looking ahead to novel therapies for chronic cough. Part 1 - peripheral sensory nerve targeted treatments

INTRODUCTION

Due to a relatively high prevalence and negative impact on quality of life chronic cough (CC) is a challenge for both patients and clinicians. There is ongoing research to address the unmet need and develop more effective antitussive treatment options. This is the first part of a series of two reviews of new antitussive medications. Medical databases (Medline, Embase and SCOPUS) and trial registries (ClinicalTrials.gov and EudraCT) were searched for studies on antitussive drugs targeting peripheral sensory nerves.

AREAS COVERED

This review presents current knowledge of peripheral receptors that are not only involved in evoking the cough reflex, but are also potentially responsible for more sustained neural alterations. Blockage of the receptors and ion channels is discussed in terms of its potential antitussive effect.

EXPERT OPINION

Although better understanding of CC mechanisms has facilitated the development of novel treatments including P2X2/3 receptor inhibitors (e.g. gefapixant), there remain several gaps in the knowledge about the mechanisms and treatment of CC. These include the lack of tests to diagnose cough hypersensitivity syndrome and predictors of response to specific treatments. Further research into cough phenotypes and endotypes will yield important insights and a personalized approach to cough management.

Mechanisms and Rationale for Targeted Therapies in Refractory and Unexplained Chronic Cough

Chronic cough, defined as a cough lasting > 8 weeks, is a common medical condition that exerts a substantial physical, mental, and social burden on patients. A subset of patients with chronic cough are troubled with a cough that persists despite optimal treatment of presumed associated common and uncommon conditions (refractory chronic cough; RCC) or in which no diagnosable cause for cough can be identified despite extensive assessment (unexplained chronic cough; UCC). Many of these patients exhibit clinical features of cough hypersensitivity, including laryngeal paresthesia, hypertussia, and allotussia. Over-the-counter cough remedies are ineffective and can lead to intolerable side effects when used for RCC/UCC, and the lack of approved treatments indicated for these conditions reflects a major unmet need. An increased understanding of the anatomy and neurophysiology of protective and pathologic cough has fostered a robust clinical development pipeline of several targeted therapies for RCC/UCC. This manuscript reviews the mechanisms presumed to underly RCC/UCC together with the rationale and clinical evidence for several targeted therapies currently under clinical investigation, including transient receptor potential channel antagonists, P2X3-receptor antagonists, voltage-gated sodium channel blockers, neuromodulators, and neurokinin-1-receptor antagonists. Finally, we provide an overview of targets that have been investigated in preclinical models of cough and other airway diseases that may hold future promise for clinical studies in RCC/UCC. Development of targeted therapies with different sites of action may foster a precision medicine approach to treat this heterogeneous, underserved patient population.

Nebulized Lidocaine in the Treatment of Refractory Postoperative Laryngospasm: A Case Report

Intraoperative laryngospasm occurs in <1% of cases. Recurrent laryngospasm is rarer. Some risk factors include shared airway and pediatric surgery, secretions, pungent volatile anesthetics, and patient factors, such as smoking and asthma. Conventional management includes the application of positive airway pressure, jaw thrust, the removal of any offending stimuli, deepening anesthesia, or administering muscle relaxants. Nebulized lidocaine is used to anesthetize the vocal cords before awake fiberoptic intubation. This case highlights the novel use of nebulized lidocaine to successfully treat refractory postoperative laryngospasm in a fully conscious adult patient after conventional measures were unsuccessful.

Chronic Cough in Adults: Make the Diagnosis and Make a Difference

Chronic cough is common and impactful, frustrating both patients and clinicians. An empirical trial of therapy is often done with inhaled corticosteroids, but this practice should be replaced with attempting to make an accurate diagnosis. The three most common causes are upper airway cough syndrome, asthma, and gastroesophageal reflux disease (GERD), but there are often multiple causes involved. Minimal investigations after history, physical exam, travel history, and drug history include a chest radiograph and spirometry. Empirical trial of therapy with inhaled corticosteroids is reasonable if there is evidence of eosinophilic inflammation. Empiric therapy for GERD may also be reasonable in those with symptoms. Red flags should especially be considered an urgency to make the correct diagnosis.

Etiology and treatment of cough in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive disease of dysregulated wound healing leading to unremitting scarring and loss of lung function. The predominant symptoms are dyspnea on exertion and a persistent dry cough. For patients with IPF, cough is more than just bothersome; it has a significant negative impact on quality of life and is a marker of disease severity and progression. The etiology of cough in IPF is unclear but may be due to architectural distortion of the lungs, increased sensitivity of the cough reflex, airway inflammation, or changes in mucus production and clearance. There also may be an overlap between IPF cough and cough due to other common etiologies such as asthma, gastroesophageal reflux disease, upper airway cough syndrome, and medications. There are no approved therapies to specifically treat IPF cough, and recently approved medications for IPF have not been evaluated in cough. Few clinical trials have focused on treatments for IPF cough. To date, there is only one randomized, placebo control therapeutic study for IPF cough with thalidomide, which significantly reduced IPF cough and improved quality of life. Two additional cohort studies report that interferon-α and prednisolone also decrease IPF cough. However, no medication is approved to treat IPF cough. Currently, the mainstay of therapy for IPF cough is standard cough suppressants, which have limited efficacy and often intolerable side effects. Future studies are needed to determine an effective therapy to alleviate this particularly debilitating symptom and improve overall quality of life for patients suffering with IPF.

Antitussive effect of carcainium chloride in patients with chronic cough and idiopathic interstitial pneumonias: A pilot study

BACKGROUND

Cough is a common presenting symptom in patients with idiopathic interstitial pneumonia (IIP); it is often disabling, and lacks effective treatment. Studies in animals suggest that carcainium chloride, a quaternary derivative of the local anesthetic lidocaine, is able to inhibit experimentally induced cough by a mechanism of action distinct from that of lidocaine.

OBJECTIVE

To determine the effectiveness of aerosolised carcainium chloride (VRP700) in controlling cough in patients with IIP.

METHODS

Eight female patients (mean age 71 years) with IIP were investigated in a double blind, randomised, placebo controlled crossover, adaptive contingency study design (EudraCT Number 2010-021350-19). The study consisted of a screening visit to assess the eligibility of patients, and two separated (48-72 h) study days. On the two study days, patients were randomised to receive either nebulized VRP700 (1.0 mg/kg) on the first study visit followed by nebulised placebo (sodium chloride 0.9%) on the second visit, or placebo on the first visit followed by VRP700 on the second visit. The primary endpoint was cough frequency over a 4-h assessment period; secondary endpoints were subjective cough-related level of discomfort as assessed by a visual analogue scale (VAS) and the subjective response to treatment as assessed by a quality of life question. Safety (ECG, spirometry, urine and blood tests) and adverse events occurring during the trial were also investigated.

RESULTS

In all patients both VRP700 and placebo decreased cough frequency; however, mean decreases in cough frequency after treatment with VRP700 were significantly (P < 0.001) higher than with placebo. Similarly, mean reductions in VAS score were significantly (P < 0.001) higher after treatment with VRP 700 compared with placebo. All but one patient indicated that they felt better after receiving VRP700. No adverse events were reported during the study, nor were any changes in ECG variables, spirometry, urine and blood tests noted.

CONCLUSION

The results of this exploratory study indicate that nebulised VRP700 improved cough and quality of life in hospitalised IIP patients with no significant side effects. A larger trial is warranted to assess these promising results.

Treatment Recommendations for Respiratory Symptoms in Cancer Patients: Clinical Guidelines from the Japanese Society for Palliative Medicine

BACKGROUND

Respiratory symptoms, dyspnea, cough, and death rattle, are common and distressing in advanced cancer patients. Palliation of respiratory symptoms is important to improve quality of life in cancer patients and their families/caregivers. Currently published clinical guidelines for the management of these respiratory symptoms in cancer patients did not cover the topics comprehensively or were not based on formal process for the development of clinical guidelines.

METHODS

The Japanese Society for Palliative Medicine (JSPM) decided to develop comprehensive clinical guidelines for the management of respiratory symptoms in cancer patients following the formal guideline developing process.

RESULTS

This article provides a summary of the recommendations with the rationales, as well as a short summary of the developing process, of the JSPM respiratory symptom management guidelines. We established 26 recommendations and all recommendations are based on the best available evidences and expert consensus.

DISCUSSION

More future clinical researches and continuous guideline updates are required to improve the quality of respiratory symptom management in cancer patients.

Associations between laryngeal and cough dysfunction in motor neuron disease with bulbar involvement

True vocal fold (TVF) dysfunction may lead to cough ineffectiveness. In individuals with motor neuron disease (MND), cough impairment in the context of dysphagia increases risk for aspiration and respiratory failure. This study characterizes differences and associations between TVF kinematics and airflow during cough in individuals with bulbar MND. Sequential glottal angles associated with TVF movements during volitional cough were analyzed from laryngeal video endoscopy examinations of adults with bulbar MND (n = 12) and healthy controls (n = 12) and compared with simultaneously collected cough-related airflow measures. Significant group differences were observed with airflow and TVF measures: volume acceleration (p ≤ 0.001) and post-compression abduction TVF angle average velocity (p = 0.002) were lower and expiratory phase rise time (p = 0.001) was higher in the MND group. Reductions in maximum TVF angle during post-compression abduction in the MND group approached significance (p = 0.09). All subjects demonstrated complete TVF and supraglottic closure during the compression phase of cough, except for incomplete supraglottic closure in 2/12 MND participants. A strong positive relationship between post-compression maximum TVF abduction angle and peak expiratory cough flow was observed in the MND group, though it was not statistically significant (r = 0.55; p = 0.098). Reductions in the speed and extent of TVF abduction are seen during the expulsion phase of cough in individuals with MND. This may contribute to cough impairment and morbidity.

Update: the search for the human cough receptor

Despite the best efforts of basic and applied science, the identity of the human "cough receptor" remains elusive. The attraction of identifying a single "catch all" cough receptor is obvious, although such an objective is unlikely to be realised given the concept of "cough hypersensitivity," which is now considered the most clinically relevant description of what underlies problem coughing. One means of progressing this area is to join the thinking and experimental effort of basic science and clinical research in an effective manner. Some of the best examples of cooperative and translational research over the years together with an update on the most recent work will be discussed in this article.

Chronic cough: an update

Cough persisting beyond 8 weeks (ie, chronic cough) is one of the most common reasons for an outpatient visit. A protracted cough can negatively affect one's quality of life by causing anxiety, physical discomfort, social isolation, and personal embarrassment. Herein, the anatomy and physiology of the cough reflex are reviewed. Upper airway cough syndrome, asthma, eosinophilic bronchitis, and gastroesophageal reflux disease account for most chronic cough after excluding smoking, angiotensin-converting enzyme inhibitor use, and chronic bronchitis. Many patients have more than one reason for chronic cough. Treating the underlying cause(s) resolves cough in most instances. There are some coughs that seem refractory despite an extensive work-up. The possibility of a hypersensitive cough reflex response has been proposed to explain these cases. Several clinical algorithms to evaluate chronic cough are presented.