Clinical Practice Guidelines for Diagnosis and Management of Cough-Chinese Thoracic Society (CTS) Asthma Consortium

Cough as a Cause and Consequence of Heart Dysfunction - Current State of Art

The cough reflex is an airway defensive process that can be modulated by afferent inputs from organs located also out of the respiratory system. A bidirectional relationship between cough and heart dysfunctions are presented in the article, with the special insights into an arrhythmia-triggered cough. Albeit rare, cough induced by cardiac pathologies (mainly arrhythmias) seems to be an interesting and underestimated phenomenon. This condition is usually associated with the presence of abnormal heart rhythms and ceases with successful treatment of arrhythmia either by pharmacotherapy or by radiofrequency ablation of arrhythmogenic substrate. The two main hypotheses on cough-heart relationships - reflex and hemodynamic - are discussed in the review, including the authors' perspective based on the experiences with an arrhythmia-triggered cough.

Arnold Nerve Reflex: Vagal Hypersensitivity in Chronic Cough With Various Causes

BACKGROUND

A higher incidence of Arnold nerve reflex (ANR) has been observed in patients with chronic cough. However, the different ANR response in various causes of chronic cough remains unclear. Furthermore, it is unknown whether ANR will change after effective treatment.

METHODS

Patients with chronic cough were enrolled in the Guangzhou Institute of Respiratory Health. The causes of chronic cough were diagnosed via a validated management algorithm. Patients underwent an assessment of ANR response before and after 1 month of etiologic treatment.

RESULTS

A total of 127 patients with chronic cough and 55 healthy control subjects were enrolled. The positive response, defined as cough-only ANR or urge-to-cough (UTC), was present in 14.8% of patients with cough variant asthma (CVA), 11.1% of patients with upper airway cough syndrome, 15.4% of patients with gastroesophageal reflex related cough (GERC), 4.8% of patients with eosinophilic bronchitis, and 26.9% of patients with unexplained cough (UC). No ANR or UTC was found in the healthy control subjects. The incidence of the positive response was higher in subjects with CVA, GERC, and UC compared with healthy control subjects (all P < .05). No difference was observed among the different causes of chronic cough (all P > .05). After 1 month of treatment, 87.5% of patients identified with a positive response changed to a negative response. In a subgroup analysis, an increased cough sensitivity to capsaicin was found in the patients with a positive response compared with the patients with a negative response (P < .05).

CONCLUSIONS

A positive ANR appears to be a sign of vagal hypersensitivity and can be reversed after effective treatment of chronic cough. However, although various causes of chronic cough share a similar feature of an elevated ANR response in a minority of patients, there appears to be limited usefulness in assessing ANR because it does not appear to be a valid predictor of etiology of chronic cough or outcome of treatment.

Current Status and Future Directions of Chronic Cough in China

Chronic cough is one of the most common complaints for which patients in China seek medical attention. However, there are no nationwide data on the prevalence and socioeconomic burden of chronic cough. Although approximately 50% of Chinese men smoke, the vast majority of patients presenting for evaluation of chronic cough are never smokers. An equal sex distribution and a middle-aged predominance have been observed in the Chinese chronic cough population, despite demonstration of a higher cough reflex sensitivity in females and older patients. The role of air pollution in the distinct age and sex distribution requires further study. In terms of the etiologies of chronic cough in China, cough-variant asthma, upper airway cough syndrome, nonasthmatic eosinophilic bronchitis, and atopic cough are the most common causes, comprising 75.2% to 87.6% of cases across different regions. Chinese Guidelines for Diagnosis and Treatment of Cough were initially published in 2005, and updated in 2009 and 2016. In addition, the China Cough Coalition was established in 2016. Great progress has been made in both cough-related clinical practice and research in recent years, however, there are still challenges ahead. To facilitate optimal management of chronic cough in China, efforts promoting the dissemination and application of published guidelines will be essential, especially in community-based healthcare and in rural regions. As chronic refractory cough has been identified as a huge challenge to clinicians worldwide, continued international cooperation will be essential in optimizing evaluation and management of chronic cough.

Suhuang Antitussive Capsules-Ameliorative Effects on LPS-Induced Sputum Obstruction in Mice Through Promoting HGF Secretion

Sputum obstruction is one of common cough complications, which is tightly associated with airway inflammation. Suhuang antitussive capsule (SH Capsule), a classic traditional Chinese medicine prescription, has been used for the treatment of post-cold cough and cough variant asthma in the long clinical application. This study aims to investigate the effects and underlying mechanisms of SH Capsule on LPS-induced sputum obstruction in mice. The results showed that SH Capsule effectively promoted the tracheal phenol red output and mucociliary clearance. SH Capsule also alleviated airway inflammation-mediated mucin 5AC (MUC5AC) level through EGFR-ERK signaling. A further in vivo analysis showed that HGF inhibitor SU11274 abrogated the effects of SH Capsule on MUC5AC, well demonstrating that HGF was required for the beneficial effects of SH Capsule on expectoration in vivo. Moreover, SH Capsule promoted HGF secretion in a colon-dependent manner, which reached lung tissues via blood circulation. Collectively, this study provided new pharmacological data for clinical use of SH Capsule, and proposed a novel mechanism by which SH Capsule was pharmacologically promising for treating sputum obstruction.

Characteristics of Chinese chronic cough patients

Chronic cough is one of the most common complains for patients seeking medical attention in both general practice and respiratory specialist clinics. Cough variant asthma, eosinophilic bronchitis, upper airway cough syndrome, as well as gastro-esophageal reflux disease are common conditions associated with chronic cough, and cough variant asthma, eosinophilic bronchitis account for a higher proportion of patients with chronic cough in China than in Western countries. An older female predominance has been reported in most Western countries, which may be attributed to a higher cough reflex sensitivity in females, especially those post-menopausal females. However, studies conducted in China showed that patients with chronic cough have a nearly similar gender distribution and most of them are in their late 30s or early 40s, despite the similar gender and age difference in cough reflex sensitivity as Western countries. Environmental and occupational exposures, cigarette smoking, unhealthy lifestyle might play a role in the distinct age and gender distribution of Chinese chronic cough patients, yet further study is needed to clarify it.