Standardization of bronchial inhalation challenge procedures
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Cough persistence in adults with chronic cough: A 4-year retrospective cohort study
2020, Allergology InternationalThere is very limited evidence regarding long-term prognosis of chronic cough. We examined longitudinal outcomes among patients with chronic cough, and explored predictors of cough persistence.
A retrospective cohort was constructed of adults who had newly visited a specialist cough clinic in 2012–2013. All had undergone systematic investigation for chronic cough. The Hull Airway Reflux Questionnaire (HARQ) was administered to assess reflux cough symptoms. A follow-up survey was conducted in 2016–2017 to assess cough persistence.
From 418 candidates, 323 participated in the follow-up study; main analyses focused on patients with chronic persistent cough (n = 64; 19.8%) and remitted cough (n = 193; 59.8%). Compared with remitted cough group, chronic persistent cough group had more family history of chronic cough (17.2% vs. 4.7%, p = 0.001) and cold air-sensitive cough (62.5% vs. 44.6%, p = 0.013). The total HARQ score did not differ; however, two items (cough with eating and cough with certain foods) scored significantly higher in chronic persistent cough. In multivariate analyses, a family history of chronic cough (adjusted odds ratio 4.27 [95% confidence interval 1.35–9.89]), cold air-sensitive cough (2.01 [1.09–3.73]), and cough with eating (1.22 [1.02–1.45]) were associated with chronic persistent cough at 4 years.
Cough persists in about 20% of patients after 4 years following systematic assessment and treatments. Several cough characteristics, such as family history, cold air-sensitivity, or reflux cough, may be associated with cough persistence. Larger cohort studies are warranted to further understand long-term prognosis and confirm predictors of persistence in patients with chronic cough.
Richard Studley Farr, MD
2018, Annals of Allergy, Asthma and ImmunologyStandardized pulmonary function testing
2018, Lung Function Testing in the 21st Century: Methodologies and Tools Bridging Engineering to Clinical PracticePulmonary function tests provide an objective index of how well the respiratory system is functioning to achieve adequate airflow, ventilation, and oxygenation. These tests assess the volumes and flows that are associated with normal tidal breathing, and forced inspiration and exhalation. Pulmonary function can be assessed through a variety of methods including body plethysmography, spirometry, gas diffusion tests, and forced oscillation technique also known as oscillometry. This chapter primarily covers two methods of assessing pulmonary function—spirometry and plethysmography. Spirometry is the gold standard for measuring lung function, and reference values are readily available for comparison.
Contrasting effects of ATP and adenosine on capsaicin challenge in asthmatic patients
2017, Pulmonary Pharmacology and TherapeuticsAdenosine 5’-triphosphate (ATP) stimulates pulmonary vagal slow conducting C-fibres and fast conducting Aδ-fibres with rapidly adapting receptors (RARs). Pulmonary C-fibres but not RARs are also sensitive to capsaicin, a potent tussigenic agent in humans. Thus, the aim of this study was to determine the effects of ATP and its metabolite adenosine (given as adenosine 5’-monophosphate, AMP) on capsaicin challenge in asthmatic patients.
Cough (quantified as visual analogue scale, VAS), dyspnoea (quantified as Borg score), and FEV1 were quantified following bronchoprovocation using capsaicin, adenosine and ATP in healthy non-smokers (age 40±4y, 6 males), smokers (45±4y, 5 males) and asthmatic patients (37±3y, 5 males); n = 10 in each group.
None of the healthy non-smokers responded to either AMP or ATP. AMP induced bronchoconstriction in one smoker and eight asthmatics, and ATP in two smokers and all ten asthmatics. The geometric mean of capsaicin causing ≥5 coughs (C5) increased from 134 to 203 μM in non-smokers and from 117 to 287 μM in asthmatics after AMP, whereas it decreased from 203 to 165 μM and 125 to 88 μM, respectively after ATP. AMP decreased C5 from 58 to 29 μM and ATP increased from 33 to 47 μM in smokers. However, due to intergroup variability, these effects of ATP and AMP were not statistically significant (0.125 ≤ p ≤ 0.998). That notwithstanding, in healthy and asthmatic subjects the effects of the ATP showed a tendency to be greater than those of AMP (p < 0.053). Dyspnea, assessed by Borg score, increased after ATP (p < 0.001) and AMP (p < 0.001) only in asthmatic patients. Intensity of cough assessed by VAS increased (p < 0.05) after second capsaicin challenges performed after AMP in all groups, but not after ATP.
Asthmatic patients exhibit hypersensitivity to aerosolized AMP and ATP, but aerosolized AMP does not mimic the effects of ATP and the effects of ATP are not mediated by adenosine.
Airway Hyperresponsiveness in Asthma: Measurement and Clinical Relevance
2017, Journal of Allergy and Clinical Immunology: In PracticeAirway hyperresponsiveness is a characteristic feature of asthma, and its measurement is an important tool in its diagnosis. With a few caveats, methacholine bronchial provocation by a 2-minute tidal breathing method is highly sensitive; a negative test result (PC20 > 16 mg/mL, PD20 > 400 μg) rules out current asthma with reasonable certainty. A PC20 value of less than 1 mg/mL/PD20 value of less than 25 μg is highly specific (ie, diagnostic) but quite insensitive for asthma. For accurate interpretation of the test results, it is important to control and standardize technical factors that have an impact on nebulizer performance. In addition to its utility to relate symptoms such as cough, wheeze, and shortness of breath to variable airflow obstruction (ie, to diagnose current asthma), the test is useful to make a number of other clinical assessments. These include (1) evaluation of patients with occupational asthma, (2) evaluation of patients with exercise-induced respiratory symptoms, (3) evaluation of novel asthma medications, (4) evaluation of relative potency of inhaled bronchodilators, (5) as a biomarker to adjust anti-inflammatory therapy to improve clinical outcomes, and (6) in the evaluation of patients with severe asthma to rule out masqueraders such as laryngeal dysfunction. The actual mechanism of altered smooth muscle behavior in asthma that is assessed by direct (eg, methacholine) or indirect (eg, allergen) bronchial provocation remains one of the most fundamental questions related to asthma that needs to be determined. The test is underutilized in clinical practice.
Lung sound analysis can be an index of the control of bronchial asthma
2017, Allergology InternationalWe assessed whether lung sound analysis (LSA) is a valid measure of airway obstruction and inflammation in patients with bronchial asthma during treatment with inhaled corticosteroids (ICSs).
63 good adherence patients with bronchial asthma and 18 poor adherence patients were examined by LSA, spirometry, fractional exhaled nitric oxide (FeNO), and induced sputum. The expiration-to-inspiration lung sound power ratio at low frequencies between 100 and 200 Hz (E/I LF) obtained by LSA was compared between healthy volunteers and bronchial asthma patients. Next, post-ICS treatment changes were compared in bronchial asthma patients between the good adherence patients and the poor adherence patients.
E/I LF was significantly higher in bronchial asthma patients (0.62 ± 0.21) than in healthy volunteers (0.44 ± 0.12, p < 0.001). The good adherence patients demonstrated a significant reduction in E/I LF from pre-treatment to post-treatment (0.55 ± 0.21 to 0.46 ± 0.16, p = 0.002), whereas the poor adherence patients did not show a significant change. The decrease of E/I LF correlated with the improvement of FEV1/FVC ratio during the ICS treatment (r = −0.26, p = 0.04). The subjects with higher pre-treatment E/I LF values had significantly lower FEV1/FVC and V50,%pred (p < 0.001), and significantly higher FeNO and sputum eosinophil percentages (p = 0.008 and p < 0.001, respectively).
The E/I LF measurement obtained by LSA is useful as an indicator of changes in airway obstruction and inflammation and can be used for monitoring the therapeutic course of bronchial asthma patients.
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