'Indirect' challenges from science to clinical practice

Hypertonic Aerosols Hydrate Airways Longer and Reduce Acidification Risk with Nonpermeating Cation and Permeating Anion Salts

Background: Hyperosmolar aerosols appear to promote or suppress upper airway dysfunction caused by dehydration in a composition-dependent manner. We sought to explore this composition dependence experimentally, in an interventional human clinical study, and theoretically, by numerical analysis of upper airway ion and water transport. Methods: In a double-blinded, placebo-controlled clinical study, phonation threshold pressure (PTP) was measured prenasal and postnasal inhalation of hypertonic aerosols of NaCl, KCl, CaCl2, and MgCl2 in seven human subjects. Numerical analysis of water and solute exchanges in the upper airways following deposition of these same aerosols was performed using a mathematical model previously described in the literature. Results: PTP decreased by 9%-22% relative to baseline (p < 0.05) for all salts within the first 30 minutes postadministration, indicating effective laryngeal hydration. Only MgCl2 reduced PTP beyond 90 minutes (21% below baseline at 2 hours postadministration). By numerical analysis, we determined that, while airway water volume up to 15 minutes postdeposition is dictated by osmolarity, after 30 minutes, divalent cation salts, such as MgCl2, better retain airway surface liquid (ASL) volume by slow paracellular clearance of the divalent cation. Fall of CFTR chloride flux with rise in ASL height, a promoter of airway acidification, appears to be a signature of permeating cation (NaCl) and nonpermeating anion (mannitol) aerosol deposition. For hypertonic aerosols that lack permeating cation and include permeating anion (CaCl2 and MgCl2), this acid-trigger signature does not exist. Conclusions: Nonpermeating cation and permeating anion hypertonic aerosols appear to hydrate upper airways longer and, rather than provoke, may reduce laryngeal dysfunction such as cough and bronchoconstriction.

Mucus Transpiration as the Basis for Chronic Cough and Cough Hypersensitivity

Chronic cough is characterized by a state of cough hypersensitivity. We analyze the process of transpiration, by which water appears to evaporate from laryngeal and tracheal mucus as from the surface of a leaf, as a potential cause of cough hypersensitivity. In this process, osmotic pressure differences form across mucus, pulling water toward the air, and preventing mucus dehydration. Recent research suggests that these osmotic differences grow on encounter with dry and dirty air, amplifying pressure on upper airway epithelia and initiating a cascade of biophysical events that potentially elevate levels of ATP, promote inflammation and acidity, threaten water condensation, and diminish mucus water permeability. Among consequences of this inflammatory cascade is tendency to cough. Studies of isotonic, hypotonic, and hypertonic aerosols targeted to the upper airways give insights to the nature of mucus transpiration and its relationship to a water layer that forms by condensation in the upper airways on exhalation. They also suggest that, while hypertonic NaCl and mannitol may provoke cough and bronchoconstriction, hypertonic salts with permeating anions and non-permeating cations may relieve these same upper respiratory dysfunctions. Understanding of mucus transpiration and its role in cough hypersensitivity can lead to new treatment modalities for chronic cough and other airway dysfunctions promoted by the breathing of dry and dirty air.

Bronchodilator Response in FEF25-75 for the Diagnosis of Asthma in Children

BACKGROUND

Spirometry tests with a bronchodilator response (BDR) in FEV1, a methacholine concentration that produces a 20% drop in FEV1 (PC20) ≤ 2 mg/mL, and a positive exercise test have high specificity for the diagnosis of asthma in children. However, the value of forced expiratory flow during the middle half of the FVC maneuver (FEF25-75) in spirometry has been questioned. The objective of this study was to relate the BDR in FEF25-75 of spirometry tests with normal FEV1 and FEV1/FVC to airway hyper-responsiveness (AHR) to methacholine or exercise in children age 5-15 y with clinical suspicion of asthma.

METHODS

This was a cross-sectional study of spirometry tests performed between January 2017-December 2019 in children age 5-15 y with diagnostic suspicion of asthma who had a methacholine and/or exercise testing within a period not exceeding 60 d between exams.

RESULTS

The mean (± SD) age of the children was 9.04 ± 2.67 y, with a range of 5-15 y, and 56.17% were male. Of the 324 spirometry tests with normal FEV1 and FEV1/FVC, 66 (20.4%) tests showed BDR in FEF25-75. A total of 46.9% and 33.3% of the children with and without BDR in FEF25-75, respectively, had a PC20 value ≤ 2 mg/mL and/or a positive exercise testing (P = .039).

CONCLUSIONS

Children with suspected asthma and normal spirometry, other than BDR in FEF25-75, had greater AHR than those without BDR in FEF25-75. BDR in FEF25-75 was not always accompanied by AHR to confirm the diagnosis of asthma, so this study suggests that assessment of FEF25-75 alone is not always reliable for ruling in or ruling out AHR in the setting of otherwise normal spirometry results in children with suspected asthma.

How to detect young athletes at risk of exercise-induced bronchoconstriction?

Exercise-induced bronchoconstriction (EIB) is a prevalent condition in elite athletes caused by transient airway narrowing during or after exercise. Young athletes nowadays start early to perform high level exercise, highlighting the need to screen for EIB in a younger population. The purpose of this review is to evaluate current evidence of pre-tests with high probability to predict a positive provocation test in young and adolescent athletes, aged 12-24 years and thus indicate whether a young athlete is at risk of having EIB. Up to now, there is no validated screening test available to increase the pre-test probability of a provocation test of EIB in young and adolescent athletes. We would recommend that a clinical guideline committee might consider the development of a flow chart to screen for EIB in adolescent athletes. It could be composed of a symptom-based questionnaire focusing on wheezing during exercise, atopic state, reversibility test (to exclude EIB with asthma) and completed with markers in blood/serum. However, more research is necessary.

Can the response to a single dose of beclomethasone dipropionate predict the outcome of long-term treatment in childhood exercise-induced bronchoconstriction?

BACKGROUND

Exercise-induced bronchoconstriction (EIB) is a frequent and highly specific symptom of childhood asthma. Inhaled corticosteroids (ICS) are the mainstay of controller therapy for EIB and asthma; however, a proportion of asthmatic children and adolescents is less responsive to ICS. We hypothesized that a single dose response to ICS could function as a predictor for individual long-term efficacy of ICS.

OBJECTIVE

To assess the predictive value of the bronchoprotective effect of a single-dose beclomethasone dipropionate (BDP) against EIB for the bronchoprotective effect of 4 weeks of treatment, using an exercise challenge test (ECT).

METHODS

Thirty-two steroid-naïve children and adolescents aged 6 to 18 years with EIB were included in this prospective cohort study. They performed an ECT at baseline, after a single-dose BDP (200µg) and after 4 weeks of BDP treatment (100 µg twice daily) to assess EIB severity.

RESULTS

The response to a single-dose BDP on exercise-induced fall in FEV1 showed a significant correlation with the response on exercise-induced fall in FEV1 after 4 weeks of BDP treatment (r = .38, p = .004). A reduction in post-exercise fall in FEV1 of more than 8% after a single-dose BDP could predict BDP efficacy against EIB after 4 weeks of treatment with a positive predictive value of 100% (CI: 86.1-100%) and a negative predictive value of 29.4% (CI: 11.7%-53.7%).

CONCLUSION

We found that the individual response to a single-dose BDP against EIB has a predictive value for the efficacy of long-term treatment with BDP. This could support clinicians in providing personalized management of EIB in childhood asthma.

Halotherapy-An Ancient Natural Ally in the Management of Asthma: A Comprehensive Review

The increasing production of modern medication emerges as a new source of environmental pollution. The scientific community is interested in developing alternative, ecological therapies in asthma. Halotherapy proved its benefits in asthma diagnosis, treatment, and prevention and may represent a reliable therapeutic addition to the allopathic treatment, due to its ecological and environment-friendly nature, in order to prevent or prolong the time to exacerbations in patients with asthma. We aimed to review up-to-date research regarding halotherapy benefits in asthma comprehensively. We searched the electronic databases of PubMed, MEDLINE, EMBASE for studies that evaluated the exposure of asthmatic patients to halotherapy. Eighteen original articles on asthma were included. Five studies in adults and five in children assessed the performance of hypertonic saline bronchial challenges to diagnose asthma or vocal cord dysfunction in asthmatic patients. Three papers evaluated the beneficial effects of halotherapy on mucociliary clearance in asthmatic adults. The therapeutic effect of halotherapy on acute or chronic asthma was appraised in three studies in adults and one in children. The preventive role was documented in one paper reporting the ability of halotherapy to hinder nocturnal asthma exacerbations. All studies seem to sustain the overall positive effects of halotherapy as adjuvant therapy on asthma patients with no reported adverse events. Halotherapy is a crucial natural ally in asthma, but further evidence-based studies on larger populations are needed.

The Need for Testing-The Exercise Challenge Test to Disentangle Causes of Childhood Exertional Dyspnea

Exertional dyspnea is a common symptom in childhood which can induce avoidance of physical activity, aggravating the original symptom. Common causes of exertional dyspnea are exercise induced bronchoconstriction (EIB), dysfunctional breathing, physical deconditioning and the sensation of dyspnea when reaching the physiological limit. These causes frequently coexist, trigger one another and have overlapping symptoms, which can impede diagnoses and treatment. In the majority of children with exertional dyspnea, EIB is not the cause of symptoms, and in asthmatic children it is often not the only cause. An exercise challenge test (ECT) is a highly specific tool to diagnose EIB and asthma in children. Sensitivity can be increased by simulating real-life environmental circumstances where symptoms occur, such as environmental factors and exercise modality. An ECT reflects daily life symptoms and impairment, and can in an enjoyable way disentangle common causes of exertional dyspnea.

The impact of regular bisoprolol on the response to salbutamol in asthma: A double-blind randomized placebo-controlled crossover trial

BACKGROUND AND OBJECTIVE

Non-selective beta-blockers impair the bronchodilator response to beta₂ -agonists. Cardio-selective beta₁ -blockers are less likely to cause this effect, yet they remain relatively contraindicated in asthma. We investigated whether the response to salbutamol is impaired during cardio-selective beta₁ -blocker treatment in people with asthma.

METHODS

A random-order, double-blind, placebo-controlled, non-inferiority, crossover study was conducted comparing up to 5 mg bisoprolol daily for 2 weeks with matching placebo, with an open-label extension of up to 10 mg bisoprolol daily. After each treatment period, mannitol was inhaled to induce bronchoconstriction with a 15% fall in forced expiratory volume in 1 s (FEV₁ ). Immediately after mannitol challenge, salbutamol (100, 100 and 200 μg) was administered via spacer at 5-min intervals with repeated FEV₁ measures. The FEV₁ recovery with salbutamol was measured as an area under recovery curve (AUC). Based on earlier research, a clinically relevant non-inferiority limit of a 30% reduction in the AUC was set.

RESULTS

A total of 19 adults with mild asthma and positive inhaled mannitol challenge completed the study. Adjusting for the FEV₁ fall induced by mannitol and treatment sequence, the mean AUC response to salbutamol after bisoprolol was 5% lower than after placebo, with a one-sided 95% confidence interval (CI) of 26% lower. Thirteen participants completed the open-label extension up to 10 mg bisoprolol daily with mean AUC 11% higher after bisoprolol with a 95% CI of 5% lower.

CONCLUSION

The bronchodilator response to rescue salbutamol after mannitol-induced bronchoconstriction is non-inferior during regular treatment with the cardio-selective beta₁ -blocker, bisoprolol, compared to placebo.

CLINICAL TRIAL REGISTRATION

ACTRN12618000306213 at https://www.anzctr.org.au.

The feasibility of eucapnic voluntary hyperpnoea for the diagnosis of exercise-induced bronchoconstriction in a community pulmonary practice

OBJECTIVE

Exercise-induced bronchoconstriction (EIB) is a common condition and is typically treated empirically based on symptoms alone. However, symptoms of EIB are typically nonspecific. Objective testing with eucapnic voluntary hyperpnea (EVH) is a sensitive and specific method to diagnose EIB and may suggest alternative etiologies such as exercise-induced laryngeal obstruction (EILO). To this point, EVH has been primarily utilized in large academic centers and in elite athletes. We intend to discuss the feasibility and clinical application of utilizing EVH to diagnose EIB in a community-based pulmonary practice.

METHODS

Retrospective analysis of 62 patients who completed EVH at The Oregon Clinic Pulmonary Clinic. Patients with inspiratory flow volume loop flattening or clinical symptoms were assessed by otolaryngology for evidence of EILO.

RESULTS

61 of 62 patients were included in the final analysis. 52 of 61 patients (85%) achieved an interpretable test with a maximum voluntary ventilation (MVV) >60%. There was no difference in baseline spirometry or patient characteristics between those who were able to reach an MVV >60% and those who did not. 14 (23%) patients were diagnosed with EIB, 18 (30%) with EILO, and 4 (7%) were diagnosed with both EIB and EILO. Only 1 patient had a non-diagnostic evaluation with MVV <60% and negative for EIB and EILO.

CONCLUSIONS

EVH is a feasible diagnostic modality to evaluate for EIB in a community pulmonary practice and may suggest alternative conditions such as EILO. Accurate diagnosis is paramount to prescribing proper therapy, decreasing inappropriate medication use, and relieving exercise-induced symptoms.

Asthma and Lung Mechanics

This article will discuss in detail the pathophysiology of asthma from the point of view of lung mechanics. In particular, we will explain how asthma is more than just airflow limitation resulting from airway narrowing but in fact involves multiple consequences of airway narrowing, including ventilation heterogeneity, airway closure, and airway hyperresponsiveness. In addition, the relationship between the airway and surrounding lung parenchyma is thought to be critically important in asthma, especially as related to the response to deep inspiration. Furthermore, dynamic changes in lung mechanics over time may yield important information about asthma stability, as well as potentially provide a window into future disease control. All of these features of mechanical properties of the lung in asthma will be explained by providing evidence from multiple investigative methods, including not only traditional pulmonary function testing but also more sophisticated techniques such as forced oscillation, multiple breath nitrogen washout, and different imaging modalities. Throughout the article, we will link the lung mechanical features of asthma to clinical manifestations of asthma symptoms, severity, and control. © 2020 American Physiological Society. Compr Physiol 10:975-1007, 2020.

Airway hyperresponsiveness to mannitol improves in both type 2 high and type 2 low asthma after specialist management

OBJECTIVES

Type 2 low (T2-low) asthma is reported to respond less to anti-inflammatory treatment compared with Type 2 high (T2-high) asthma. Airway hyperresponsiveness (AHR) to mannitol, a marker of airway mast cell activation, may be indicative of response to treatment in patients with T2-low disease. We investigated whether AHR to mannitol improves in patients with T2-low asthma after specialist management.

METHODS

Patients with asthma or suspected asthma, referred to our specialist outpatient clinic, were enrolled consecutively and assessed with FeNO, asthma control, blood eosinophils, mannitol and methacholine tests and induced sputum. T2-low asthma was defined in patients with FeNO < 25ppb and sputum eosinophils < 3% and blood eosinophils < 300µl^-1 at inclusion. Patients with asthma and AHR to mannitol (PD15 ≤ 635 mg) were followed and reassessed after 12 months of specialist management.

RESULTS

Thirty-two patients (Females: 56%, age: 22 years (15-59)) were followed. Fourteen (44%) with T2-high and 18 (56%) with T2-low asthma. Baseline AHR to mannitol was comparable: G_mean PD15: 150 mg (95% CI 61-368) and 214 mg (95% CI 106-432) for T2-high and T2-low asthma respectively (P = 0.51). Both groups improved equally: G_mean PD15: 488 mg (95% CI 311-767) and 507 mg (95% CI 345-746); corresponding to a doubling-dose of: 3.00 (95% CI 1.58-5.74, P = 0.003) and 2.28 (95% CI 1.47-3.53, P = 0.001) respectively. There were no concomitant improvements in AHR to methacholine.

CONCLUSION

Patients with asthma and AHR to mannitol improve similarly in responsiveness to mannitol after 12 months of specialist management regardless of Type 2 inflammatory biomarker levels. Mechanisms driving AHR in T2-low asthma need to be further elucidated.

Cough-provocation tests with hypertonic aerosols

Recent advances in cough research suggest a more widespread use of cough-provocation tests to demonstrate the hypersensitivity of the cough reflex arc. Cough-provocation tests with capsaicin or acidic aerosols have been used for decades in scientific studies. Several factors have hindered their use in everyday clinical work: i.e. lack of standardisation, the need for special equipment and the limited clinical importance of the response. Cough-provocation tests with hypertonic aerosols (CPTHAs) involve provocations with hypertonic saline, hypertonic histamine, mannitol and hyperpnoea. They probably act via different mechanisms than capsaicin and acidic aerosols. They are safe and well tolerated and the response is repeatable. CPTHAs can assess not only the sensitivity of the cough reflex arc but also the tendency of the airway smooth muscles to constrict (airway hyper-responsiveness). They can differentiate between subjects with asthma or chronic cough and healthy subjects. The responsiveness to CPTHAs correlates with the cough-related quality of life among asthmatic subjects. Furthermore, the responsiveness to them decreases during treatment of chronic cough. A severe response to CPTHAs may indicate poor long-term prognosis in chronic cough. The mannitol test has been stringently standardised, is easy to administer with simple equipment, and has regulatory approval for the assessment of airway hyper-responsiveness. Manual counting of coughs during a mannitol challenge would allow the measurement of the function of the cough reflex arc as a part of clinical routine.

Cough-provocation tests with hypertonic aerosols offer the possibility to measure the function of the cough reflex arc even in everyday clinical workhttp://bit.ly/2RTOfMI

Predictors and reproducibility of exercise-induced bronchoconstriction in cold air

Background

Physical activity is an important part of life, and hence exercise-induced bronchoconstriction (EIB) can reduce the quality of life. A standardized test is needed to diagnose EIB. The American Thoracic Society (ATS) guidelines recommend an exercise challenge in combination with dry air. We investigated the feasibility of a new, ATS guidelines conform exercise challenge in a cold chamber (ECC) to detect EIB. The aim of this study was to investigate the surrogate marker reaction to methacholine, ECC and exercise challenge in ambient temperature for the prediction of a positive reaction and to re-evaluate the reproducibility of the response to an ECC.

Methods

Seventy-eight subjects aged 6 to 40 years with suspected EIB were recruited for the study. The subjects performed one methacholine challenge, two ECCs, and one exercise challenge at an ambient temperature. To define the sensitivity and specificity of the predictor, a receiver-operating characteristic curve was plotted. The repeatability was evaluated using the method described by Bland and Altman (95% Limits of agreement).

Results

The following cut-off values showed the best combination of sensitivity and specificity: the provocation dose causing a 20% decrease in the forced expiratory volume in 1 s (PD₂₀FEV₁) of methacholine: 1.36 mg (AUC 0.69, p < 0.05), the maximal decrease in FEV₁ during the ECC: 8.5% (AUC 0.78, p < 0.001) and exercise challenges at ambient temperatures: FEV₁ 5.2% (AUC 0.64, p = 0.13). The median decline in FEV₁ was 14.5% (0.0–64.2) during the first ECC and 10.7% (0.0–52.5) during the second ECC. In the comparison of both ECCs, the Spearman rank correlation of the FEV₁ decrease was r = 0.58 (p < 0.001). The 95% limits of agreement (95% LOAs) for the FEV₁ decrease were − 17.7 to 26.4%.

Conclusions

The surrogate markers PD₂₀FEV₁ of methacholine and maximal decrease in FEV₁ during ECC can predict a positive reaction in another ECC, whereas the maximal FEV₁ decrease in an exercise challenge at an ambient temperature was not predictive. Compared with previous studies, we can achieve a similar reproducibility with an ECC.

Clinical trial registration

NCT02026492 (retrospectively registered 03/Jan/2014).

Usefulness of mannitol challenge testing for diagnosing asthma in everyday clinical practice

Background: The mannitol test is widely used for assessment of airway responsiveness in patients with possible asthma, but our knowledge of the value in everyday clinical practice is limited.Objective: To investigate the diagnostic value of the mannitol test in a clinical setting.Methods: All patients having a mannitol challenge test as part of their diagnostic work-up for asthma at the respiratory outpatient clinic, Hvidovre Hospital, over a 5-year period were included in the present analysis. Case history, including previous diagnoses, spirometry, exhaled nitric oxide (F_ENO) was obtained. The mannitol challenge was performed according to guidelines, i.e. increasing doses of mannitol (from 5 to 635 mg) until maximum dose or a 15% decline in FEV₁ (PD₁₅) was achieved (positive test defined as a PD₁₅ < 635 mg).Results: Our cohort comprised 566 patients (210 men). Post-challenge, 247 patients were diagnosed with asthma by a specialist in respiratory medicine, of whom 138 (56%) had a positive mannitol test. A diagnosis of asthma was ruled out by the specialist in 319 individuals, of whom 18 (6%) had a positive mannitol test and 77 (24%) previous doctor-diagnosed asthma (but with no evidence of a confirmatory test). The specificity and sensitivity of the test was 94% and 56%, respectively. Female gender (p = 0.005), increasing BMI (p < 0.001), exercise-induced cough (p = 0.002), night-time respiratory symptoms (p = 0.002), low FEV₁/FVC ratio (p = 0.008) and high F_ENO (p < 0.001) were determinants for a positive mannitol test.Conclusion: In everyday clinical work-up of patients with possible asthma, the sensitivity and specificity of the mannitol challenge test is comparable to previous controlled trials.

Testing for Exercise-Induced Bronchoconstriction

Exercise-induced bronchoconstriction (EIB) is a form of airway hyperresponsiveness that occurs with or without current symptoms of asthma. EIB is an indicator of active and treatable pathophysiology in persons with asthma. The objective documentation of EIB permits the identification of an individual who may be at risk during a recreational sporting activity or when exercising as an occupational duty. EIB can be identified with laboratory exercise testing or surrogate tests for EIB. These include eucapnic voluntary hyperpnea and osmotic stimuli (eg, inhaled mannitol) and offer improved diagnostic sensitivity to identify EIB and improved standardization when compared with laboratory exercise.

ERS technical standard on bronchial challenge testing: pathophysiology and methodology of indirect airway challenge testing

Recently, this international task force reported the general considerations for bronchial challenge testing and the performance of the methacholine challenge test, a "direct" airway challenge test. Here, the task force provides an updated description of the pathophysiology and the methods to conduct indirect challenge tests. Because indirect challenge tests trigger airway narrowing through the activation of endogenous pathways that are involved in asthma, indirect challenge tests tend to be specific for asthma and reveal much about the biology of asthma, but may be less sensitive than direct tests for the detection of airway hyperresponsiveness. We provide recommendations for the conduct and interpretation of hyperpnoea challenge tests such as dry air exercise challenge and eucapnic voluntary hyperpnoea that provide a single strong stimulus for airway narrowing. This technical standard expands the recommendations to additional indirect tests such as hypertonic saline, mannitol and adenosine challenge that are incremental tests, but still retain characteristics of other indirect challenges. Assessment of airway hyperresponsiveness, with direct and indirect tests, are valuable tools to understand and to monitor airway function and to characterise the underlying asthma phenotype to guide therapy. The tests should be interpreted within the context of the clinical features of asthma.

Asthma and exercise-induced respiratory symptoms in the athlete: new insights

PURPOSE OF REVIEW

Asthma and exercise-induced bronchoconstriction (EIB) are common in the athlete and can interfere with sport performances. In this review, we report recent findings on the prevalence, diagnosis and evaluation of these conditions, in addition to specific issues regarding their treatment and antidoping regulations.

RECENT FINDINGS

Recent studies confirmed the high prevalence of exercise-induced respiratory symptoms, asthma and EIB, in athletes and showed that these conditions are still underdiagnosed and undertreated. Recent studies highlight the suboptimal use of asthma medication in asthmatic and allergic athletes. Regarding the diagnosis and treatment, questions about the role and criteria for positivity of eucapnic voluntary hyperpnea test were raised. It was confirmed that there is a subgroup of athletes with poor response to asthma medication. Finally, regarding antidoping regulations, new methods and changes in criteria for urinary bronchodilator thresholds were suggested.

SUMMARY

Recent publications confirm that exercise-induced respiratory symptoms, asthma and EIB are common in athletes but often unrecognized and not optimally or successfully treated. It was suggested that current criteria for diagnostic bronchoprovocation test responses could be reassessed, as well as antidoping criteria for β2-agonists urinary levels. There is a need for more research on prevention of airways dysfunction in athletes, identification of different asthma phenotypes and the benefits of standard asthma medication in this population.

Realising the potential of various inhaled airway challenge agents through improved delivery to the lungs

Inhaled airway challenges provoke bronchoconstriction in susceptible subjects and are a pivotal tool in the diagnosis and monitoring of obstructive lung diseases, both in the clinic and in the development of new respiratory medicines. This article reviews the main challenge agents that are in use today (methacholine, mannitol, adenosine, allergens, endotoxin) and emphasises the importance of controlling how these agents are administered. There is a danger that the optimal value of these challenge agents may not be realised due to suboptimal inhaled delivery; thus considerations for effective and reproducible challenge delivery are provided. This article seeks to increase awareness of the importance of precise delivery of inhaled agents used to challenge the airways for diagnosis and research, and is intended as a stepping stone towards much-needed standardisation and harmonisation in the administration of inhaled airway challenge agents.

Noninvasive ventilation and respiratory physical therapy reduce exercise-induced bronchospasm and pulmonary inflammation in children with asthma: randomized clinical trial

BACKGROUND

Asthma is characterized by hyperresponsiveness of the airways, and exercise-induced bronchospasm (EIB) is a symptom that limits a large proportion of asthmatic patients, especially children. Continuous positive airway pressure (CPAP) leads to a reduction in the reactivity of the airways. The aim of this study was to evaluate the effect of outpatient treatment with CPAP and bilevel pressure combined with respiratory physical therapy for children and adolescents with asthma following bronchial hyperresponsiveness caused by an exercise bronchoprovocation test.

METHODS

A randomized, controlled, blind, clinical trial was conducted involving 68 asthmatic children and adolescents aged 4 to 16 years divided into three groups: G1, treated with bilevel pressure (inspiratory positive airway pressure: 12 cm H2O; expiratory positive airway pressure: 8 cm H2O), G2, treated with CPAP (8 cm H2O) and G3, treated with respiratory muscle training (RMT), considered as the control group. All groups were treated at an outpatient clinic and submitted to 10 1-hour sessions, each of which also included respiratory exercises. Evaluations were performed before and after treatment and involved spirometry, an exercise bronchoprovocation test, respiratory pressures, fraction of nitric oxide (FeNO), the Asthma Control Questionnaire (ACQ6) and anthropometric variables. This study received approval from the local ethics committee (certificate number: 1487225/2016) and is registered with ClinicalTrials [ ClinicalTrials.gov identifier: NCT02939625].

RESULTS

A total of 64 patients concluded the protocol; the mean age of the patients was 10 years. All were in the ideal weight range and had adequate height ( z score: -2 to +2). The three groups demonstrated improved asthma control after the treatments, going from partial to complete control. A significant increase in maximal inspiratory pressure occurred in the three groups, with the greatest increase in the RMT group. A reduction in FeNO in the order of 17.4 parts per billion (effect size: 2.43) and a reduction in bronchial responsiveness on the exercise bronchoprovocation test occurred in the bilevel group. An improvement in FeNO on the order of 15.7 parts per billion (effect size: 2.46) and a reduction in bronchial responsiveness occurred in the CPAP group. No changes in lung function or responsiveness occurred in the RMT group.

CONCLUSION

Positive pressure and respiratory exercises were effective in reducing pulmonary inflammation, exercise-innduced bronchoespasm (EIB), and increased the clinical control of asthma, as well as RMT, which also resulted in improved clinical control.

Club cell protein (CC16) in plasma, bronchial brushes, BAL and urine following an inhaled allergen challenge in allergic asthmatics

BACKGROUND

Club cell protein (CC16) is a pneumoprotein secreted by epithelial club cells. CC16 possesses anti-inflammatory properties and is a potential biomarker for airway epithelial damage. We studied the effect of inhaled allergen on pulmonary and systemic CC16 levels.

METHODS

Thirty-four subjects with allergic asthma underwent an inhaled allergen challenge. Bronchoscopy with bronchoalveolar lavage (BAL) and brushings was performed before and 24 h after the challenge. CC16 was quantified in BAL and CC16 positive cells and CC16 mRNA in bronchial brushings. CC16 was measured in plasma and urine before and repeatedly after the challenge. Thirty subjects performed a mannitol inhalation challenge prior to the allergen challenge.

RESULTS

Compared to baseline, CC16 in plasma was significantly increased in all subjects 0-1 h after the allergen challenge, while CC16 in BAL was only increased in subjects without a late allergic response. Levels of CC16 in plasma and in the alveolar fraction of BAL correlated significantly after the challenge. There was no increase in urinary levels of CC16 post-challenge. Mannitol responsiveness was greater in subjects with lower baseline levels of CC16 in plasma.

CONCLUSIONS

The increase in plasma CC16 following inhaled allergen supports the notion of CC16 as a biomarker of epithelial dysfunction.

Hypertonic saline inhibits airway smooth muscle contraction by inhibiting Ca2+ sensitization

The effects of hypertonic solution on airway smooth muscle (ASM) contraction and the underlying mechanisms are largely unknown. We found that hypertonic saline (HS) inhibited acetylcholine (ACh)-induced contraction of ASM from the mouse trachea and human bronchi. In single mouse ASM cells (ASMCs), ACh induced an increase in intracellular Ca²⁺ that was further enhanced by 5% NaCl, indicating that the HS-induced inhibition of ASM contraction was not mediated by a decrease in cytosolic Ca²⁺ . The Rho-associated kinase (ROCK) inhibitor Y-27632 relaxed ACh-induced precontraction of mouse tracheal rings. However, such inhibition was not observed after the relaxation induced by 5% NaCl. Moreover, the incubation of mouse tracheal rings with 5% NaCl decreased ACh-induced phosphorylation of myosin light chain 20 and myosin phosphatase target subunit 1. These data indicate that HS inhibits the contraction of ASM by inhibiting Ca²⁺ sensitization, not by decreasing intracellular Ca²⁺ .

Comparison of diagnostic validity of mannitol and methacholine challenges and relationship to clinical status and airway inflammation in steroid-naïve asthmatic patients

OBJECTIVES

The purpose of this study was to demonstrate and compare the diagnostic validity of two bronchial challenges and to investigate their correlation with patient clinical status, atopy and inflammation markers.

METHODS

Eighty-eight patients, 47 women and 41 men, mean age 38.56 ± 16.73 years who presented with asthma related symptoms and were not on any anti-asthma medication, were challenged with mannitol and methacholine on separate days. Medical history regarding asthmatic symptoms, physical examination, skin prick tests and FeNO levels were also assessed. The clinical diagnosis of asthma was based on bronchodilator reversibility test.

RESULTS

Sixty-seven patients were diagnosed with asthma and 21 without asthma. Both methacholine (P < 0.014) and mannitol (P < 0.000) challenges were significant in diagnosing asthma. The positive/negative predictive value was 93.33%/41.86% for methacholine, 97.72%/45.45% for mannitol and 97.05%/45.45%. for both methods assessed together. Worthy of note that 22% of asthmatics had both tests negative. There was a negative correlation between PC20 of methacholine and the FeNO level P < 0.001, and positive with the PD15 of mannitol P < 0.001 and the pre-test FEV₁% pred P < 0.005, whereas PD15 of mannitol was negatively correlated with the FeNO level P < 0.001. Furthermore, dyspnea was the only asthmatic symptom associated with FeNO level P < 0.035 and the positivity of mannitol P < 0.014 and methacholine P < 0.04.

CONCLUSIONS

Both challenge tests were equivalent in diagnosing asthma. Nevertheless, specificity appeared to be slightly higher in mannitol challenge.