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The purpose of this state-of-the-art review is to update the American College of Chest Physicians 2006 guideline on global physiology and pathophysiology of cough. A review of the literature was conducted using PubMed and MEDLINE databases from 1951 to 2019 and using prespecified search terms. We describe the basic phenomenology of cough patterns, behaviors, and morphological features. We update the understanding of mechanical and physiological characteristics of cough, adding a contemporary view of the types of cough and their associated behaviors and sensations. New information about acoustic characteristics is presented, and recent insights into cough triggers and the patient cough hypersensitivity phenotype are explored. Lastly, because the clinical assessment of patients largely focuses on the duration rather than morphological features of cough, we review the morphological features of cough that can be measured in the clinic. This is the first of a two-part update to the American College of Chest Physicians 2006 cough guideline; it provides a more global consideration of cough phenomenology, beyond simply the mechanical aspects of a cough. A greater understanding of the typical features of cough, and their variations, may allow a more informed interpretation of cough measurements and the clinical relevance for patients.

Background: Evidence for the diagnosis and management of cough due to acute bronchitis in immunocompetent adult outpatients was reviewed as an update to the 2006 “Chronic Cough Due to Acute Bronchitis: American College of Chest Physicians (ACCP) Evidence-Based Clinical Practice Guidelines.” Methods: Acute bronchitis was defined as an acute lower respiratory tract infection manifested predominantly by cough with or without sputum production, lasting no more than 3 weeks with no clinical or any recent radiographic evidence to suggest an alternative explanation. Two clinical population, intervention, comparison, outcome questions were addressed by systematic review in July 2017: (1) the role of investigations beyond the clinical assessment of patients presenting with suspected acute bronchitis, and (2) the efficacy and safety of prescribing medication for cough in acute bronchitis. An updated search was undertaken in May 2018. Results: No eligible studies relevant to the first question were identified. For the second question, only one relevant study met eligibility criteria. This study found no difference in number of days with cough between patients treated with an antibiotic or an oral nonsteroidal antiinflammatory agent compared with placebo. Clinical suggestions and research recommendations were made based on the consensus opinion of the CHEST Expert Cough Panel. Conclusions: The panelists suggested that no routine investigations be ordered and no routine medications be prescribed in immunocompetent adult outpatients first presenting with cough due to suspected acute bronchitis, until such investigations and treatments have been shown to be safe and effective at making cough less severe or resolve sooner. If the cough due to suspected acute bronchitis persists or worsens, a reassessment and consideration of targeted investigations should be considered.

Background: Chronic cough due to chronic bronchitis (CB) causes significant impairment in quality of life, and effective treatment strategies are needed. We conducted a systematic review on the management of chronic cough due to CB to update the recommendations and suggestions of the American College of Chest Physicians (CHEST) 2006 guideline on this topic. Methods: This systematic review asked three questions: (1) What are the clinical features of the history that suggest a patient's cough-phlegm syndrome is due to CB? (2) Can treatment of stable CB improve or eliminate chronic cough? (3) Can therapy that targets chronic cough due to CB prevent or reduce the occurrence of acute CB exacerbations? Studies of adult patients with CB were included and assessed for relevance and quality. Based on the systematic review, guideline suggestions were developed and voted on by using the CHEST organization methodology. Results: The search strategy used an assortment of descriptors and assessments to identify studies of chronic cough due to CB. Conclusions: The evidence supporting the management of chronic cough due to CB is limited overall and of low quality. This article provides guidance on treatment by presenting suggestions based on the best currently available evidence and identifies gaps in our knowledge and areas for future research.

Background: Asthma and non-asthmatic eosinophilic bronchitis (NAEB) are among the commonest causes of chronic cough in adults. We sought to determine the role of non-invasive measurements of airway inflammation, including induced sputum and fractional exhaled nitric oxide, in the evaluation of cough associated with asthma, and what the best treatment is for cough due to asthma or NAEB. Methods: We undertook three systematic reviews of randomized controlled trials and observational trials of adults and adolescents > 12 years of age with a chronic cough due to asthma or NAEB. Eligible studies were identified in MEDLINE, CENTRAL, and SCOPUS and assessed for relevance and quality. Guidelines were developed and voted upon using CHEST guideline methodology. Results: Of the citations reviewed, 3/1,175, 53/656, and 6/134 were identified as being eligible for inclusion in the three systematic reviews, respectively. In contrast to established guidelines for asthma therapies in general and the inclusion in some guidelines for a role of biomarkers of airway inflammation to guide treatment in severe disease, the evidence of specific benefit related to the use of non-invasive biomarkers in patients with chronic cough due to asthma was weak. The best therapeutic option for cough in asthma or NAEB is inhaled corticosteroids followed by leukotriene receptor antagonism. Conclusions: This guideline offers recommendations on the role of non-invasive measurements of airway inflammation and treatment for cough due to asthma or NAEB based on the available literature, and identifies gaps in knowledge and areas for future research.

Background: Cough is one of the most common presenting symptoms to general practitioners. The objective of this article is to collate the pediatric components of the CHEST chronic cough guidelines that have recently updated the 2006 guidelines to assist general and specialist medical practitioners in the evaluation and management of children who present with chronic cough. Methods: We reviewed all current CHEST Expert Cough Panel's statements and extracted recommendations and suggestions relating to children aged ≤ 14 years with chronic cough (> 4 weeks duration). Additionally, we undertook systematic reviews to update other sections we considered relevant and important. Results: The eight recent CHEST guidelines relevant to children, based on systematic reviews, reported some high-quality evidence in the management of chronic cough in children (eg, use of algorithms and management of wet/productive cough using appropriate antibiotics). However, much evidence is still inadequate, particularly in the management of non-specific cough in the community. Conclusions: The recommendations and suggestions related to the management of chronic cough in the pediatric age group have been based upon high-quality systematic reviews and are summarized in this article. Compared to the 2006 Cough Guidelines, there is now high-quality evidence for some aspects of the management of chronic cough in children. However, further studies particularly in primary health care are required.

BACKGROUND: Whether gastroesophageal reflux (GER) or GER disease (GERD) causes chronic cough in children is controversial. Using the Population, Intervention, Comparison, Outcome (PICO) format, we undertook four systematic reviews. For children with chronic cough (> 4-weeks duration) and without underlying lung disease: (1) who do not have gastrointestinal GER symptoms, should empirical treatment for GERD be used? (2) with gastrointestinal GER symptoms, does treatment for GERD resolve the cough? (3) with or without gastrointestinal GER symptoms, what GER-based therapies should be used and for how long? (4) if GERD is suspected as the cause, what investigations and diagnostic criteria best determine GERD as the cause of the cough? METHODS: We used the CHEST Expert Cough Panel's protocol and American College of Chest Physicians (CHEST) methodological guidelines and GRADE (Grading of Recommendations Assessment, Development and Evaluation) framework. Delphi methodology was used to obtain consensus. RESULTS: Few randomized controlled trials addressed the first two questions and none addressed the other two. The single meta-analysis (two randomized controlled trials) showed no significant difference between the groups (any intervention for GERD vs placebo for cough resolution; OR, 1.14; 95% CI, 0.45-2.93; P ¼.78). Proton pump inhibitors (vs placebo) caused increased serious adverse events. Qualitative data from existing CHEST cough systematic reviews were consistent with two international GERD guidelines. CONCLUSIONS: The panelists endorsed that: (1) treatment(s) for GERD should not be used when there are no clinical features of GERD; and (2) pediatric GERD guidelines should be used to guide treatment and investigations.

Cough is one of the most common reasons that patients seek medical attention. Cough guidelines from numerous countries and societies are available to assist the clinician to investigate and manage patients with cough. We review some of the recent progress in the field of cough that may lead to revision of these guidelines. In adults with chronic cough, new causes such as obstructive sleep apnoea have been identified. A new terminology, cough hypersensitivity syndrome (CHS), has been proposed for patients with chronic cough, which emphasises cough reflex hypersensitivity as a key feature. New therapeutic options are now available, particularly for patients with refractory or idiopathic chronic cough, which include gabapentin, speech pathology management and morphine. There has been great progress in the assessment of cough with the development of validated quality of life questionnaires and cough frequency monitoring tools. In children, common aetiologies differ from adults and those managed according to guidelines have better outcomes compared to usual care. New diagnostic entities such as protracted bacterial bronchitis have been described. Paediatric-specific cough assessment tools such as the Parent/Child Quality of Life Questionnaire will help improve the assessment of patients. Further research is necessary to improve the evidence base for future clinical guideline recommendations. Guidelines in future should also aim to reach a wider audience that includes primary care physicians, non-specialists and patients.