Small-airway obstruction, dynamic hyperinflation, and gas trapping despite normal airway sensitivity to methacholine in adults with chronic cough.

The clinical relevance of cough during methacholine challenge in individuals with normal airway sensitivity is unknown. We compared responses of individuals with chronic cough who cough during high-dose methacholine bronchoprovocation and have normal versus increased airway sensitivity to healthy controls. Fifteen healthy participants (CONTROL) aged 26 ± 7 yr (mean ± SD) and 32 participants aged 42 ± 14 yr with chronic cough and suspected asthma completed high-dose methacholine challenge testing. Three participants who did not cough and had normal airway sensitivity were excluded. Spirometry and lung volumes were compared at the maximum response (MAX) among 1) ASTHMA [ n = 15, provocative concentration of methacholine causing a 20% fall in forced expiratory volume in 1 s (FEV1) from baseline (PC20) 4.71 ± 1.37 mg/ml], 2) methacholine-induced cough with normal airway sensitivity (COUGH, n = 14, PC20 41.2 ± 18.7 mg/ml for 3 participants with a measurable PC20), and 3) CONTROL ( n = 15; PC20 93.4 ± 95.4 mg/ml for 4 participants with a measurable PC20). Esophageal pressure-derived pulmonary mechanics were compared at MAX for the ASTHMA and COUGH groups. From baseline to MAX, FEV1 and forced expiratory flow between 25% and 75% of forced vital capacity decreased more in ASTHMA (-36.2 ± 3.8 %pr; -47.1 ± 6.9 %pr, respectively) than COUGH (-12.2 ± 3.0 %pr ( P < 0.001); -24.7 ± 6.5 %pr ( P < 0.001), respectively) and CONTROL (-13.7 ± 2.0 %pr ( P < 0.001); -32.8 ± 5.4 %pr ( P < 0.017), respectively). In both ASTHMA and COUGH, inspiratory capacity decreased by 500-800 ml, and functional residual capacity and residual volume increased by ~800 ml. Individuals with COUGH develop dynamic hyperinflation and gas trapping comparable to individuals with ASTHMA despite less bronchoconstriction and smaller reductions in mid-to-late expiratory flows, which leads us to believe that COUGH is a distinct phenotype. NEW & NOTEWORTHY Healthy individuals and individuals with chronic cough who demonstrate normal airway sensitivity but cough during methacholine bronchoprovocation bronchoconstrict less than individuals with mild asthma. However, those who cough and have normal airway sensitivity develop dynamic hyperinflation and gas trapping comparable to individuals with mild asthma. Thus, methacholine-induced cough with normal airway sensitivity may be clinically relevant, related to reversible small airway obstruction and preservation of the bronchodilating and/or bronchoprotective effects of deep inspirations.

Bronchoprotective effect of deep inspirations in cough variant asthma: A distinguishing feature in the spectrum of airway disease?

PURPOSE: To assess the effect of deep inspirations (DIs) on airway behaviour in individuals with classic asthma (CA), cough variant asthma (CVA), and methacholine (MCh)-induced cough but normal airway sensitivity (COUGH) during bronchoprovocation. METHODS: Twenty-five adults (18 female; 44.8 ±â€¯12.3 years (Mean ±â€¯SD); n = 9 CA, n = 9 CVA, and n = 7 COUGH) completed two single-dose MCh challenges, with and without DIs. Bronchoprotection was assessed by comparing changes in bronchoconstriction (FEV1, FVC, FEV1/FVC, FEF50, FEF25-75), gas trapping (RV, RV/TLC) and impulse oscillometry (IOS) measurements. RESULTS: The% changes in FEV1 with and without DIs were not significantly different within any group. Decreases in FEF50 and FEF25-75 were greater in CA (p = 0.041 and p = 0.029), decreases in FVC (% predicted) and FEV1/FVC(%) were less in CVA (p = 0.048 and p = 0.010), and increases in RV (L) and RV/TLC (% predicted) were less in COUGH (p = 0.007 and p = 0.028), respectively. No differences in IOS measurements were noted. CONCLUSIONS: DIs triggered bronchoconstriction in CA, bronchoprotection in CVA, and prevented gas trapping in COUGH.

Bronchodilating effect of deep inspirations in asthma and chronic cough.

The pathophysiologic processes distinguishing classic asthma (CA), cough-variant asthma (CVA), and methacholine (MCh)-induced cough but normal airway sensitivity (COUGH) are inadequately understood and may be a result of differences in the ability to bronchodilate following a deep inspiration (DI). The purpose of this study was to compare the bronchodilating effect of DIs in individuals with CA, CVA, and COUGH using high-dose MCh. Individuals aged 18-65 yr with CA or suspected CVA completed high-dose MCh testing to a maximum change in forced expiratory volume in 1 s (FEV1) of 50% from baseline (MAX). Impulse oscillometry (IOS) measurements and partial and maximal-flow volume curves (used to calculate a DI index) were recorded at baseline and at each dose of MCh. Body plethysmography was performed at baseline and MAX. Twenty-eight subjects [25 women, 39.8 ± 11.9 yr (means ± SD)] were studied (n = 11 CA, n = 10 CVA, and n = 7 COUGH). At MAX, the percent change in FEV1 was greater in subjects with CA compared with those with CVA (P < 0.001) and COUGH (P < 0.001), and the percent change in forced vital capacity was greater in those with CA than with COUGH (P = 0.017). Subjects with CA and CVA developed dynamic hyperinflation and gas trapping. In subjects with CA and CVA, all IOS parameters were significantly increased from baseline to MAX, except for central respiratory resistance (R20). In individuals with COUGH, total respiratory resistance, R20, and resonant frequency were significantly increased from baseline. At MAX, the DI index was positive in all groups, suggesting preserved bronchodilation (CA, 0.67 ± 0.97; CVA, 0.51 ± 0.73; COUGH, 0.01 ± 0.36; P = 0.211). We conclude that the bronchodilating effect of DIs is preserved in individuals with CA, CVA, and borderline with COUGH; however, hyperinflation and gas trapping are avoided in subjects with COUGH alone.

The development and test re-test reliability of a work-related asthma screening questionnaire.

OBJECTIVE: Work-related asthma (WRA) is under-recognized and delays in recognition contribute to long-term morbidity. The objective of the project was to develop a WRA screening questionnaire for use by primary care providers in the assessment of individuals with asthma, and to evaluate the respondent burden, test re-test reliability and face validity of the questionnaire. METHODS: A literature search was undertaken and an expert advisory committee was convened. A questionnaire was drafted and assessed for feasibility of use and content validity. The study enrolled patients with asthma attending outpatient clinics and an asthma education center. Participants were asked to respond to the questionnaire on two occasions, and comment on the content (face validity) and ease of completion (respondent burden). Ethics approval was obtained from an institutional review board. RESULTS: A 14-item self-administered screening questionnaire was created. Thirty-nine participants were recruited, and 26 participants completed a second administration of the questionnaire. The items on the relation of asthma symptoms to work demonstrated substantial agreement between testings. The workplace exposures items were found to have good reproducibility. The majority of participants denied that items were repetitive, not useful or difficult to understand. CONCLUSIONS: We have developed a WRA screening questionnaire designed to aid primary care providers in the recognition of possible WRA. The tool exhibited content and face validity, good test re-test reliability and low respondent burden. Participant feedback is being considered in revisions of the questionnaire.

Randomized trial of Nordic walking in patients with moderate to severe heart failure.

BACKGROUND: Patients with heart failure are a growing population within cardiac rehabilitation. The purpose of this study was to compare, through a single-centre, parallel-group, randomized controlled trial, the effects of Nordic walking and standard cardiac rehabilitation care on functional capacity and other outcomes in patients with moderate to severe heart failure. METHODS: Between 2008 and 2009, 54 patients (aged 62.4 ± 11.4 years) with heart failure (mean ejection fraction = 26.9% ± 5.0%) were randomly assigned to standard cardiac rehabilitation care (n = 27) or Nordic walking (n = 27); both groups performed 200 to 400 minutes of exercise per week for 12 weeks. The primary outcome, measured after 12 weeks, was functional capacity assessed by a 6-minute walk test (6MWT). RESULTS: Compared with standard care, Nordic walking led to higher functional capacity (Δ 125.6 ± 59.4 m vs Δ 57.0 ± 71.3 m travelled during 6MWT; P = 0.001), greater self-reported physical activity (Δ 158.5 ± 118.5 minutes vs Δ 155.5 ± 125.6 minutes; P = 0.049), increased right grip strength (Δ 2.3 ± 3.5 kg vs Δ 0.3 ± 3.1 kg; P = 0.026), and fewer depressive symptoms (Hospital Anxiety and Depression Scale score = Δ -1.7 ± 2.4 vs Δ -0.8 ± 3.1; P = 0.014). No significant differences were found for peak aerobic capacity, left-hand grip strength, body weight, waist circumference, or symptoms of anxiety. CONCLUSIONS: Nordic walking was superior to standard cardiac rehabilitation care in improving functional capacity and other important outcomes in patients with heart failure. This exercise modality is a promising alternative for this population.

Flock worker's lung disease: natural history of cases and exposed workers in Kingston, Ontario.

BACKGROUND: The natural history of flock worker's lung (FWL) and longitudinal lung function changes in nylon flock-exposed workers have not been well characterized. METHODS: Symptoms, pulmonary function testing, and chest radiographs from five index cases, subsequent case referrals, and screened employees of a flocking plant in Kingston, Ontario, Canada, were compared and analyzed for changes over time (variable follow-up intervals between 1991 and 2011). RESULTS: Nine cases and 30 flock-exposed workers without FWL were identified. Four cases had persistent interstitial lung disease despite three having left the workplace. Two developed hypoxemic respiratory failure and secondary pulmonary hypertension and died of complications 18 and 20 years after diagnosis, respectively. Five cases resolved after leaving the workplace. Compared with resolved cases, persistent cases had lower diffusing capacity of the lung for carbon monoxide at presentation (P < .05) and follow-up (P < .05). Among exposed workers employed for 14.5 ± 4.7 years, five had abnormal chest radiographs vs none at baseline (P = .001) over 14.8 ± 4.6 years of follow-up. The prevalence of wheeze increased (P = .001), and FEV1/FVC decreased (P < .001). FEV1% predicted was significantly lower at follow-up (P = .05). Average FEV1 decline was 46 mL/year (range, -27 to 151 mL/y). Seventy-seven percent of exposed workers were current or former smokers. CONCLUSIONS: The natural history of FWL includes the following patterns: complete resolution of symptoms; radiographic and pulmonary function abnormalities; permanent, but stable symptoms and restrictive pulmonary function deficits; and progressive decline in pulmonary function, causing death from respiratory failure and secondary pulmonary hypertension. A low baseline diffusing capacity of the lung for carbon monoxide is associated with the persistence and progression of FWL.

Cough variant asthma: lessons learned from deep inspirations.

The pathophysiology of cough variant asthma is poorly understood. In particular, the mechanisms that cause different symptoms in typical asthma (in which wheeze predominates) compared with cough variant asthma (in which cough predominates) have not been determined. Traditional explanations include higher wheezing thresholds, differences in cough sensitivity, and/or differences in small airway function. Recent studies using high-dose methacholine challenge testing suggest that altered small-airway function plays a role. Preservation or loss of the bronchoprotective effect of a deep inspiration may be a fundamental pathophysiologic difference between asthma, cough variant asthma, methacholine-induced cough with normal sensitivity, and eosinophilic bronchitis.

Cough in asthma.

Asthma is one of the most common causes of chronic cough, and cough may be the sole or predominant symptom of asthma. The mechanisms of cough in asthma are complex and presumbably multi-factorial. In particular, the pathophysiologic basis of cough variant versus classic asthma is poorly understood. Recent research utilizing various inhalation challenge tests suggests that preservation of the bronchodilating and bronchoprotective effects of deep inspirations is a distinguishing feature of cough variant asthma. This review outlines the tussive agents used in cough research (including tussive and direct, indirect and combined bronchoconstrictive stimuli), their mechanisms of action, the receptors involved in eliciting cough, and characteristic responses in classic asthma and cough variant asthma.

Asthma electronic medical records in primary care: an integrative review.

BACKGROUND: Quality management, evaluation, and surveillance of asthma may be enhanced by access to and utilization of an asthma electronic medical record (EMR) in primary care. PURPOSE: To describe the current status, support tools, and utility of asthma EMRs in primary care. METHODS: An integrative review of the literature published between 1996 and 2008 was completed using Ovid MEDLINE, EMBASE, and CINAHL databases. Key search terms included asthma, medical records, computerized, primary health care, primary care, family physician, family practice, chronic disease, COPD, neoplasm, diabetes mellitus, and cardiovascular disease. Articles related to concepts, systems in development, and sources such as acute care and pharmacy EMRs were excluded. Each article was reviewed by two reviewers. RESULTS: Of 309 articles identified, 76 met the inclusion criteria. Twenty-two percent were specific to asthma, 78% pertained to other chronic diseases and/or the overall status of an EMR in primary care. The literature varied in methodology, topics of discussion and value of data. Articles describing an asthma EMR most often reported on decision support tools (n = 3) and/or utility (n = 14), specifically the ability to predict mortality and assess severity and timeliness of diagnosis. A primary care EMR containing a validated asthma minimum data set was not found. Three themes emerged from the review: status (description of users, functionalities and adoption issues), tools (decision support tools to enhance knowledge uptake), and utility (data quality, extraction and outcomes). CONCLUSIONS: There is a paucity of asthma elements in EMRs in primary care, with the exception of discussion of decision support tools and utility. Integration of a more robust asthma EMR in primary care, including a minimum data set, standardized terminology, and validated indicators, may further enhance care and enable outcomes monitoring.