Cough - Latest Articles

Validation of the ERS standard citric acid cough challenge in healthy adult volunteers

Caroline Wright — 2010-08-10T00:00:00Z

Protocols measuring cough sensitivity can vary in terms of nebuliser, tussive agent, single and dose response. A definitive method for measuring cough sensitivity needs to be established.The ERS guidelines recommend the KoKo DigiDoser (KD) delivery system. Study aim, was to compare the reproducibility of this citric acid (CA) cough challenge and previously established Mefar dosimeter (MD) protocol.39 (female 26) volunteers mean age (40.4 yrs) were randomised to either KD or MD. Intra-day and inter-day reproducibility was compared.We calculated the concentration of citric acid evoking 2 coughs (C2).The geometric mean C2 (95%CI) was similar for both KD and MD, of 263 (200,339) mM and 209 (151,288) mM respectively.The mean KD C2 was not significantly different. (F = 0.807, p = 0.93) from baseline over 1, 2, and 4 hrs however, the MD demonstrated significant variability (F = 7.85, P < 0.001)Measuring mean log C2 at baseline and at 2 weeks, the KD demonstrated a stronger intraclass correlation of log C2 at baseline with 2 week log C2, ICC = 0.70 than was shown with the Mefar, ICC = 0.41Administering CA from KD offers a reproducible cough challenge in healthy volunteers. The results correlate well with the MD challenge but offer greater intra-day and inter-day reproducibility.Trial RegistrationCurrent controlled trials ISRCTN98385033

Role of COX-2 in cough reflex sensitivity to inhaled capsaicin in patients with sinobronchial syndrome

Yoshihisa Ishiura — 2010-08-09T00:00:00Z

Background: Sinobronchial syndrome is a cause of chronic productive cough. Inflammatory mediators are involved in the pathophysiology of chronic productive cough. Accumulating evidences indicate that cyclooxygenase (COX)-2, one of the inducible isoforms of COX, is a key element in the pathophysiological process of a number of inflammatory disorders. However, little is known about the role of COX-2 in chronic productive cough in patients with sinobronchial syndrome known as neutrophilic bronchial inflammation. Methods: The effect of etodolac, a potent COX-2 inhibitor, on cough response to inhaled capsaicin was examined in 15 patients with sinobronchial syndrome in a randomized, placebo-controlled cross-over study. Capsaicin cough threshold, defined as the lowest concentration of capsaicin eliciting five or more coughs, was measured as an index of airway cough reflex sensitivity. Results: The cough threshold was significantly (p < 0.03) increased after two-week treatment with etodolac (200 mg twice a day orally) compared with placebo [37.5 (GSEM 1.3) vs. 27.2 (GSEM 1.3) μM]. Conclusions: These findings indicate that COX-2 may be a possible modulator augmenting airway cough reflex sensitivity in patients with sinobronchial syndrome.

Chronic cough associated with Crohn's disease

Shoaib Faruqi — 2010-08-08T00:00:00Z

A 62-year-old man presented with chronic dry cough. He was known to have Crohn's disease which was in remission. A plain chest radiograph demonstrated bilateral apical infiltrates. A HRCT of the chest showed normal proximal airways. Stenosis of medium size airways was present with post-stenotic dilation. These dilated peripheral bronchi appeared fluid filled. Patchy areas of consolidation were seen as well. These changes were thought to be due to Crohn's disease involving the lungs and responded well to treatment with cortico-steroids. We report this uncommon radiological association with Crohn's disease.

Cough reflex sensitivity improves with speech language pathology management of refractory chronic cough

Nicole Ryan — 2010-07-28T00:00:00Z

RationaleSpeech language pathology is an effective management intervention for chronic cough that persists despite medical treatment. The mechanism behind the improvement has not been determined but may include active cough suppression, reduced cough sensitivity or increased cough threshold from reduced laryngeal irritation. Objective measures such as cough reflex sensitivity and cough frequency could be used to determine whether the treatment response was due to reduced underlying cough sensitivity or to more deliberate control exerted by individual patients. The number of treatments required to effect a response was also assessed.ObjectiveThe aim of this study was to investigate subjective and objective measures of cough before, during and after speech language pathology treatment for refractory chronic cough and the mechanism underlying the improvement. Methods: Adults with chronic cough (n = 17) were assessed before, during and after speech language pathology intervention for refractory chronic cough. The primary outcome measures were capsaicin cough reflex sensitivity, automated cough frequency detection and cough-related quality of life. Results: Following treatment there was a significant improvement in cough related quality of life (Median (IQR) at baseline: 13.5 (6.3) vs. post treatment: 16.9 (4.9), p = 0.002), objective cough frequency (Mean ± SD at baseline: 72.5 ± 55.8 vs. post treatment: 25 ± 27.9 coughs/hr, p = 0.009), and cough reflex sensitivity (Mean ± SD log C5 at baseline: 0.88 ± 0.48 vs. post treatment: 1.65 ± 0.88, p < 0.0001). Conclusions: This is the first study to show that speech language pathology management is an effective intervention for refractory chronic cough and that the mechanism behind the improvement is due to reduced laryngeal irritation which results in decreased cough sensitivity, decreased urge to cough and an increased cough threshold. Speech language pathology may be a useful and sustained treatment for refractory chronic cough.Trial RegistrationAustralian New Zealand Clinical Trials Register, ACTRN12608000284369.

Objective cough frequency in Idiopathic Pulmonary Fibrosis

Angela Key — 2010-06-21T00:00:00Z

Background: Cough is a common presenting symptom in patients with Idiopathic Pulmonary Fibrosis (IPF). This study measured cough rates in IPF patients and investigated the association between cough and measures of health related quality of life and subjective cough assessments. In addition, IPF cough rates were related to measures of physiological disease severity and compared to cough rates in health and other respiratory conditions. Methods: Nineteen IPF patients, mean age 70.8 years ± 8.6, five female (26.3%) were studied. Subjects performed full pulmonary function testing, 24 hour ambulatory cough recordings, completed a cough related quality of life questionnaire (Leicester Cough Questionnaire) and subjectively scored cough severity with a visual analogue scale. Ambulatory cough recordings were manually counted and reported as number of coughs per hour. Results: The 24hr cough rates were high (median 9.4, range 1.5-39.4), with day time rates much higher than night time (median 14.6, range 1.9-56.6 compared to 1.9, range 0-19.2, p = 0.003). Strong correlations were found between objective cough frequency and both the VAS (day r = 0.80, p < 0.001, night r = 0.71, p = 0.001) and LCQ (r = -0.80, p < 0.001), but not with measures of pulmonary function. Cough rates in IPF were higher than healthy subjects (p < 0.001) and asthma patients (p < 0.001) but similar to patients with chronic cough (p = 0.33). Conclusions: This study confirms objectively that cough is a major, very distressing and disabling symptom in IPF patients. The strong correlations between objective cough counts and cough related quality of life measures suggest that in IPF patient's, perception of cough frequency is very accurate.

Validation of an ambulatory cough detection and counting application using voluntary cough under different conditions

Eldad Vizel — 2010-05-27T00:00:00Z

Background: While cough is an important defence mechanism of the respiratory system, its chronic presence is bothersome and may indicate the presence of a serious disease. We hereby describe the validation process of a novel cough detection and counting technology (PulmoTrack-CC™, KarmelSonix, Haifa, Israel). Methods: Tracheal and chest wall sounds, ambient sounds and chest motion were digitally recorded, using the PulmoTrack® hardware, from healthy volunteers coughing voluntarily while (a) laying supine, (b) sitting, (c) sitting with strong ambient noise, (d) walking, and (e) climbing stairs, a total of 25 minutes per subject. The cough monitoring algorithm was applied to the recorded data to detect and count coughs.The detection algorithm first searches for cough 'candidates' by identifying loud sounds with a cough pattern, followed by a secondary verification process based on detection of specific characteristics of cough. The recorded data were independently and blindly evaluated by trained experts who listened to the sounds and visually reviewed them on a sonogram display.The validation process was based on two methods: (i) Referring to an expert consensus as gold standard, and comparing each cough detected by the algorithm to the expert marking, we marked True and False, positive and negative detections.These values were used to evaluate the specificity and sensitivity of the cough monitoring system. (ii) Counting the number of coughs in longer segments (t = 60 sec, n = 300) and plotting the cough count vs. the corresponding experts' count whereby the linear regression equation, the regression coefficient (R2) and the joint-distribution density Bland-Altman plots could be determined. Results: Data were recorded from 12 volunteers undergoing the complete protocol. The overall Specificity for cough events was 94% and the Sensitivity was 96%, with similar values found for all conditions, except for the stair climbing stage where the Specificity was 87% with Sensitivity of 97%. The regression equation between the PulmoTrack-CC™ cough event counts and the Experts' determination was with R2 of 0.94.DiscussionThis validation scheme provides an objective and quantitative assessment method of a cough counting algorithm in a range of realistic situations that simulate ambulatory monitoring of cough. The ability to detect voluntary coughs under acoustically challenging ambient conditions may represent a useful step towards a clinically applicable automatic cough detector.

Chronic cough and obstructive sleep apnea in a community-based pulmonary practice

Krishna Sundar — 2010-04-15T00:00:00Z

Background: Recent reports suggest an association between unexplained chronic cough and obstructive sleep apnea (OSA). Current guidelines provide an empiric integrative approach to the management of chronic cough, particularly for etiologies of gastroesophageal reflux (GERD), upper airway cough syndrome (UACS) and cough variant asthma (CVA) but do not provide any recommendations regarding testing for OSA. This study was done to evaluate the prevalence of OSA in patients referred for chronic cough and examine the impact of treating OSA in resolution of chronic cough. Methods: A retrospective review of chronic cough patients seen over a four-year period in a community-based pulmonary practice was done. Patients with abnormal chest radiographs, abnormal pulmonary function tests, history of known parenchymal lung disease, and inadequate followup were excluded. Clinical data, treatments provided and degree of resolution of cough was evaluated based on chart review. Specifically, diagnostic testing for OSA and impact of management of OSA on chronic cough was assessed. Results: 75 patients with isolated chronic cough were identified. 44/75 had single etiologies for cough (GERD 37%, UACS 12%, CVA 8%). 31/75 had multiple etiologies for their chronic cough (GERD-UACS 31%, GERD-CVA 5%, UACS-CVA 3%, GERD-UACS-CVA 3%). 31% patients underwent further diagnostic testing to evaluate for UACS, GERD and CVA. Specific testing for OSA was carried out in 38/75 (51%) patients and 33/75 (44%) were found to have obstructive sleep apnea. 93% of the patients that had interventions to optimize their sleep-disordered breathing had improvement in their cough. Conclusions: OSA is a common finding in patients with chronic cough, even when another cause of cough has been identified. CPAP therapy in combination with other specific therapy for cough leads to a reduction in cough severity. Sleep apnea evaluation and therapy needs to considered early during the management of chronic cough and as a part of the diagnostic workup for chronic cough.

Perception of urge-to-cough and dyspnea in healthy smokers with decreased cough reflex sensitivity

Masashi Kanezaki — 2010-02-05T00:00:00Z

Background: Although cigarette smoking has been implicated as an important risk factor for the development of respiratory symptoms, the perceptional aspects of two symptoms in smokers have not been fully elucidated. Therefore, we simultaneously evaluated the cough reflex sensitivity, the cognition of urge-to-cough and perception of dyspnea in both healthy smokers and non-smokers. Methods: Fourteen male healthy never-smokers and 14 age-matched male healthy current-smokers were recruited via public postings. The cough reflex sensitivity and the urge-to-cough were evaluated by the inhalation of citric acid. The perception of dyspnea was evaluated by Borg scores during applications of external inspiratory resistive loads. Results: The cough reflex threshold to citric acid, as expressed by the lowest concentration of citric acid that elicited two or more coughs (C2) and the lowest concentration of citric acid that elicited five or more coughs (C5) in smokers was significantly higher than in non-smokers. The urge-to-cough log-log slope in smokers was significantly milder than that of non-smokers. There were no significant differences in the urge-to-cough threshold between non-smokers and smokers. There were no significant differences in perceptions of dyspnea between non-smokers and smokers. Conclusions: The study showed that decreased cough reflex sensitivity in healthy smokers was accompanied by a decreased cognition of urge-to-cough whereas it was not accompanied by the alternation of perception of dyspnea. Physicians should pay attention to the perceptual alterations of cough in smokers.

Spatiotemporal regulation of the cough motor pattern

Cheng Wang — 2009-12-22T00:00:00Z

The purpose of this study was to identify the spatiotemporal determinants of the cough motor pattern. We speculated that the spatial and temporal characteristics of the cough motor pattern would be regulated separately. Electromyograms (EMG) of abdominal muscles (ABD, rectus abdominis or transversus abdominis), and parasternal muscles (PS) were recorded in anesthetized cats. Repetitive coughing was produced by mechanical stimulation of the lumen of the intrathoracic trachea. Cough inspiratory (CTI) and expiratory (CTE) durations were obtained from the PS EMG. The ABD EMG burst was confined to the early part of CTE and was followed by a quiescent period of varying duration. As such, CTE was divided into two segments with CTE1 defined as the duration of the ABD EMG burst and CTE2 defined as the period of little or no EMG activity in the ABD EMG. Total cough cycle duration (CTTOT) was strongly correlated with CTE2 (r2>0.8), weakly correlated with CTI (r2<0.3), and not correlated with CTE1 (r2<0.2). There was no significant relationship between CTI and CTE1 or CTE2. The magnitudes of inspiratory and expiratory motor drive during cough were only weakly correlated with each other (r2<0.36) and were not correlated with the duration of any phase of cough. The results support: a) separate regulation of CTI and CTE, b) two distinct subphases of CTE (CTE1 and CTE2), c) the duration of CTE2 is a primary determinant of CTTOT, and d) separate regulation of the magnitude and temporal features of the cough motor pattern.

Acute cough: a diagnostic and therapeutic challenge

Peter Dicpinigaitis — 2009-12-16T00:00:00Z

Background: Acute cough is one of the most common complaints prompting patient visits to healthcare professionals. Despite the broad repercussions of acute cough on patient quality of life, school and work productivity, and public health resources, research on this condition is minimal, as are the available treatment options. Many patients use over-the-counter medicines, which are often ineffective for symptom relief. Some therapies may achieve antitussive activity, but at the expense of unpleasant or intolerable side effects.Unmet needsWhen considering the treatments currently available for the management of acute cough, the multiple limitations of such treatments are quite apparent. Most of these treatments lack clinically proven efficacy and reliability to support their use. This reinforces the need for the generation of quality scientific data from well-performed clinical trials. Hopefully, the result will be the development of safer, more effective and more reliable therapeutic options in the management of acute cough.Cough assessment and managementAcute cough can be due to a variety of causes, and it is worthwhile to consider these pathogenic factors in some detail. It is also important to be familiar with the effects that acute cough has on patients' quality of life, work productivity, and the healthcare system; proper awareness of these effects may contribute to better understanding of the social impact of cough. In reference to the available treatments for the management of acute cough, adequate knowledge of the type of over-the-counter and prescription products in the market, as well as their mode of action and advantages/disadvantages, may provide expanded pharmacotherapeutic opportunities and facilitate better clinical decisions. However, due to the drawbacks of current treatment options, ideas for future cough management and newer products need to be considered and tested. Conclusion: In view of the socio-economic impact of acute cough and the limitations of available treatments, a renewed interest in the management of acute cough needs to be encouraged. The current strategies for acute cough management need to be reassessed, with a focus on developing new, reliable products and formulations with proven efficacy and safety.