Peter V. Dicpinigaitis

Diagnosis and management of cough executive summary: ACCP evidence-based clinical practice guidelines

Recognition of the importance of cough in clinical medicine was the impetus for the original evidence-based consensus panel report on “Managing Cough as a Defense Mechanism and as a Symptom,” published in 1998,1 and this updated revision. Compared to the original cough consensus statement, this revision (1) more narrowly focuses the guidelines on the diagnosis and treatment of cough, the symptom, in adult and pediatric populations, and minimizes the discussion of cough as a defense mechanism; (2) improves on the rigor of the evidence-based review and describes the methodology in a separate section; (3) updates and expands, when appropriate, all previous sections; and (4) adds new sections with topics that were not previously covered. These new sections include nonasthmatic eosinophilic bronchitis (NAEB); acute bronchitis; nonbronchiectatic suppurative airway diseases; cough due to aspiration secondary to oral/pharyngeal dysphagia; environmental/occupational causes of cough; tuberculosis (TB) and other infections; cough in the dialysis patient; uncommon causes of cough; unexplained cough, previously referred to as idiopathic cough; an empiric integrative approach to the management of cough; assessing cough severity and efficacy of therapy in clinical research; potential future therapies; and future directions for research.

ERS guidelines on the assessment of cough

### Cough 1) All basic scientific articles should refer to cough as a three-phase motor act. For the purposes of acoustic recordings in clinical studies, however, cough should be described as a forced expulsive manoeuvre or manoeuvres against a closed glottis that are associated with a characteristic sound or sounds. 2) All scientific articles should include a clear definition of what the authors have used as their definition of cough. ### Capsaicin and citric acid inhalation cough challenge 1) The methodology for the performance of inhalation cough challenge should be standardised so as to facilitate universal interpretation and comparison of data generated by different laboratories. 2) Comprehensive normal ranges need to be developed using the standardised methodology advocated in the present document. 3) The single-breath concentration–response method using a flow-limited dosimeter is recommended for most experimental protocols. 4) Both C2 and C5 should be recorded. 5) Since there is wide inter-individual variation, cough challenge data have no intrinsic significance, but may usefully be used to follow change in cough reflex sensitivity in an individual. ### Cough induced by inhalation of aqueous solutions 1) Aerosolised aqueous solutions represent a useful experimental tool in cough research. 2) The cough challenge with ultrasonic distilled water (fog) is difficult to standardise since it is highly dependent upon nebuliser output. 3) Consideration should be given to potential adverse events, such as bronchoconstriction and cross-infection. ### Cough monitors 1) No cough monitor is currently the gold standard. 2) Monitors should be developed that are ambulatory, are capable of being digitally processed and permit prolonged (24-h) recording. 3) There is little to commend any particular method of quantifying cough over any other. ### Assessment of quality of life of patients with chronic cough 1) Cough can have profound effects on health status, which can be assessed by cough-specific health status questionnaires. 2) Cough visual analogue scale (VAS, 0–100 mm) should be used to assess cough severity in patients with chronic cough. 3) Patients with chronic cough should be assessed with cough-specific quality-of-life questionnaires in clinical studies. ### Animal models of cough 1) The most useful animal model of cough is …

The diagnosis and management of chronic cough

Fig. 1.— Overview of the evaluation of chronic cough in an adult. ACE-I: angiotensin converting enzyme inhibitor; PEF: peak expiratory flow; PNDS: post-nasal drip syndrome; GORD: gastro-oesophageal reflux disease. Fig. 2.— Therapeutic algorithm. ACE: angiotensin-converting enzyme; GORD: gastro-oesophageal reflux disease. Fig. 3.— Investigational algorithm. CT: computed tomography. Fig. 4.— Diagnostic algorithm for the approach to children with chronic cough. ENT: ear, nose and throat; PFT: pulmonary function testing; BAL: bronchoalveolar lavage; CT: computed tomography; tbc: total blood count; CMV: cytomegalovirus; PCR: polymerase chain reaction; MRI: magnetic resonance imaging; NO: nitric oxide; BHR: bronchial hyperresponsiveness. CONTENTS Chronic cough, here defined as a cough of >8 weeks duration, is a common and frequently debilitating symptom 1, 2 that is often viewed as an intractable problem. However, theexperience of specialist cough clinics is that a very high success rate, in the order of 90%, can be achieved (table 1⇓) 3–15. The key to successful management is to establish a diagnosis and to treat the cause of cough. Truly idiopathic cough is rare and misdiagnosis common, particularly because of the failure to recognise that cough is often provoked from sites outside the airway. These guidelines aim to distil the lessons from these reports and provide a framework for a logical care pathway for patients with this highly disabling symptom. View this table: Table 1— Commonest causes of chronic cough in patients investigated in specialist clinics There are three common causes of chronic cough that arise from three different anatomical areas. This varied presentation explains the major reason for the success of multidisciplinary cough clinics compared with general clinics 16. As asthma, reflux and rhinitis are the realms of different specialists who have little experience in the diagnosis of conditions outside their expertise, a patient with chronic cough may not undergo full evaluation. This problem is exacerbated by the frequently atypical presentation of …

Antitussive Effect of the Leukotriene Receptor Antagonist Zafirlukast in Subjects with Cough-Variant Asthma*

Cough-variant asthma (CVA) occurs in a subgroup of asthmatics whose sole or predominant respiratory symptom is cough. Although bronchodilators are often sufficient to treat CVA, refractory cough may require therapy with inhaled or systemic corticosteroids. In a randomized, double-blind, placebo-controlled, crossover study, we examined the effect of a 14-day course of the leukotriene receptor antagonist zafirlukast on subjective cough score and cough-reflex sensitivity to inhaled capsaicin in eight subjects with CVA refractory to inhaled beta agonists, and in five subjects refractory to inhaled corticosteroids. Seven of eight subjects experienced significant subjective and objective improvement in cough after treatment with zafirlukast. Mean (± SEM) cough score improved from 7.75 ± 0.56 to 3.25 ± 0.84 (p = 0.0006). Cough sensitivity to capsaicin was suppressed by zafirlukast in all subjects. Patients with CVA may represent a distinct subgroup of asthmatics whose afferent cough receptors within the respiratory epithelium are hypersensitive relative to those of patients with the typical form of asthma. Zafirlukast appears to be particularly effective in treating CVA by inhibiting the sensitivity of these receptors. Leukotriene receptor antagonists may offer an alternative to corticosteroids for the treatment of CVA refractory to inhaled bronchodilators.

Expert opinion on the cough hypersensitivity syndrome in respiratory medicine

In 2011, a European Respiratory Society Task Force embarked on a process to determine the position and clinical relevance of the cough hypersensitivity syndrome, a disorder characterised by troublesome coughing often triggered by low levels of thermal, mechanical or chemical exposure, in the management of patients with chronic cough. A 21-component questionnaire was developed by an iterative process supported by a literature review. 44 key opinion leaders in respiratory medicine were selected and interviewed as to their opinions. There was a high degree of unanimity in the responses obtained, with all opinion leaders supporting the concept of cough hypersensitivity as a clinically useful paradigm. The classic stratification of cough into asthmatic, rhinitic and reflux-related phenotypes was supported. Significant disparity of opinion was seen in the response to two questions concerning the therapy of chronic cough. First, the role of acid suppression in reflux cough was questioned. Secondly, the opinion leaders were split as to whether a trial of oral steroids was indicated to establish a diagnosis of eosinophilic cough. The cough hypersensitivity syndrome was clearly endorsed by the opinion leaders as a valid and useful concept. They considered that support of patients with chronic cough was inadequate and the Task Force recommends that further work is urgently required in this neglected area. Cough hypersensitivity syndrome was clearly endorsed by opinion leaders as a valid and useful concept http://ow.ly/zxk83

Alternative mechanisms for tiotropium

Tiotropium is commonly used in the treatment of chronic obstructive pulmonary disease. Although largely considered to be a long-acting bronchodilator, its demonstrated efficacy in reducing the frequency of exacerbations and preliminary evidence from early studies indicating that it might slow the rate of decline in lung function suggested mechanisms of action in addition to simple bronchodilation. This hypothesis was examined in the recently published UPLIFT study and, although spirometric and other clinical benefits of tiotropium treatment extended to four years, the rate of decline in lung function did not appear to be reduced by the addition of tiotropium in this study. This article summarizes data from a variety of investigations that provide insights into possible mechanisms to account for the effects of tiotropium. The report summarizes the discussion on basic and clinical research in this field.

Short- and long-term reproducibility of capsaicin cough challenge testing

The tussive agent capsaicin has achieved common usage in clinical research because it induces cough in a safe, dose-dependent, and reproducible manner. However, the reproducibility of capsaicin challenge testing has been demonstrated only in the short term (study intervals of 20 min to 14 days). In the present study, evaluation of data from several hundred cough challenges performed in the authors laboratory yielded two groups of 40 subjects. In the short-term reproducibility group, subjects underwent cough challenge at an interval of 14 days. Subjects in the long-term reproducibility group were challenged at intervals of at least 6 months (mean 16.7+/-2.4 months, range 6-62 months). All subjects were healthy adult volunteers who underwent identical cough challenge testing, which involved inhalation of incremental, doubling concentrations (microM) of capsaicin until the concentrations inducing two or more (C(2)) and five or more coughs (C(5)) were reached. Results were evaluated in terms of the percentage of subjects whose repeat studies yielded C(2) and C(5) values within one and two doubling concentrations of the initial values. Overall, reproducibility was quite good, with 90-100% of challenges yielding C(2) and C(5) values within two doubling concentrations. Short-term reproducibility of C(5) was superior to that of C(2), suggesting that C(5) is the preferred end point for trials involving serial cough challenges performed within a 14-day period.

Phase II, Randomized, Multicenter, Double-Blind, Placebo-Controlled Trial of a Polyclonal Anti-Staphylococcus aureus Capsular Polysaccharide Immune Globulin in Treatment of Staphylococcus aureus Bacteremia

ABSTRACT New treatment modalities are needed for the treatment of infections due to multidrug-resistant Staphylococcus aureus. S. aureus capsular polysaccharide immune globulin (Altastaph) is a polyclonal immune globulin preparation that is being developed as adjunctive therapy for persons with S. aureus infections complicated by bacteremia. In a phase II, multicenter, randomized, double-blind, placebo-controlled trial, 40 subjects with documented S. aureus bacteremia received standard therapy plus either Altastaph at 200 mg/kg of body weight in each of two infusions 24 h apart or placebo. During the 42-day observation period, antibody pharmacokinetics and safety were the primary characteristics studied. Information regarding the resolution of bacteremia and fever was also analyzed. Anti-type-5 and anti-type-8 capsular antibody levels peaked after the second infusion at 550 μg/ml and 419 μg/ml, respectively, and remained above 100 μg/ml at day 28. A total of 316 adverse events were noted in 39 of 40 subjects. Infusion-related adverse events in Altastaph recipients were infrequent and similar to those among recipients of commercial intravenously administered immunoglobulin G products. Five of 21 (23%) subjects in the Altastaph group died, whereas 2 of 18 (11%) subjects in the placebo group died (P = 0.42). Compared to the control patients, the Altastaph recipients had a shorter median time to the resolution of fever (2 days and 7 days, respectively; P = 0.09) and a shorter length of hospital stay (9 days and 14 days, respectively; P = 0.03). However, these findings are exploratory, and there were few differences in the other variables measured. High levels of opsonizing antibodies were maintained for the initial 4 weeks. Although the study was not powered to show efficacy, these preliminary findings and safety profile suggest that Altastaph may be an effective adjunct to antibiotics and warrants further investigation (ClinicalTrials.gov number NCT00063089).

Inhibition of Capsaicin‐Induced Cough by the γ‐Aminobutyric Acid Agonist Baclofen

γ‐aminobutyric acid (GABA) is a central inhibitory neurotransmitter that also exists in the lungs. The GABA‐agonist baclofen has been shown to have antitussive activity via a central mechanism in animals. Recently it was demonstrated that a 14‐day course of baclofen given three times daily significantly inhibits the cough reflex in healthy volunteers. Because of the prolonged antitussive effect of baclofen that has been previously observed, the present study was conducted to evaluate the antitussive effect of low‐dose, oral baclofen given once daily. Forty‐one healthy volunteers were randomly assigned in a double‐blind manner to receive a 28‐day course of baclofen, either 10 mg or 20 mg once daily, or placebo. Subjects underwent cough challenge testing with inhaled capsaicin to establish baseline cough reflex sensitivity, and subsequently after 14 and 28 days of therapy. Subjects receiving baclofen 20 mg daily demonstrated significant inhibition of cough sensitivity after 14 days and after 28 days of therapy compared with baseline. Neither placebo nor baclofen 10 mg daily had a significant effect on cough sensitivity. No serious side effects were experienced by any study participant. These results confirm the recent observation that baclofen has significant antitussive activity in humans. Further, once‐daily administration of a relatively low dose of baclofen is sufficient to achieve significant cough inhibition, although at least 14 to 28 days of therapy may be required to attain maximal antitussive effect. These results support further investigation of baclofen or other GABA‐agonists as potential therapeutic agents for chronic, nonproductive cough.

Treatment of Chronic, Refractory Cough with Baclofen

Chronic, nonproductive cough may result from enhanced sensitivity of the cough reflex. Often, this debilitating symptom is refractory to standard antitussive therapy. Baclofen, an agonist of γ-aminobutyric acid (GABA), has been shown, in animals, to have antitussive activity via a central mechanism. Recently, in normal subjects, we have demonstrated the ability of baclofen to inhibit capsaicin-induced cough, as well as cough due to angiotensin-converting enzyme (ACE) inhibitors. Herein, we describe two patients with chronic, refractory cough who obtained symptomatic improvement after a 14-day course of low-dose, oral baclofen, administered in a double-blind, placebo-controlled manner. In addition, both subjects demonstrated significant increases in cough threshold to inhaled capsaicin after treatment with baclofen.