Perception of dyspnea during acetylcholine-induced bronchoconstriction in asthmatic children

Peak Flow Feedback Intervention Improves Underperception of Airflow Limitation in Pediatric Asthma: A Randomized Clinical Trial

Rationale: Underperception of asthma symptoms is associated with poor asthma outcomes. Objectives: We assessed the effects of a behavioral intervention for improving perception of airflow limitation and asthma outcomes. Methods: A two-arm randomized controlled trial compared peak expiratory flow (PEF) feedback versus supportive counseling. Latino and Black adolescents with asthma ages 10-17 years old and caregivers were recruited from hospitals in the Bronx, New York. PEF feedback sessions reviewed accuracy of PEF guesses and medication adherence data and targeted behavior change using motivational interviewing and problem-solving skills training. The supportive counseling group received emotional support related to asthma. Both groups received three sessions across 6 weeks. All participants were blinded to PEF while guessing PEF before intervention and at 1, 6, and 12-month follow-up. Children in the PEF feedback group saw actual PEF after guesses were locked in during the 6-week intervention. Participants and assessors were blinded to group assignment. The primary outcome was underperception of airflow limitation (divergence between actual PEF and guesses) on home spirometers. Secondary outcomes included daily PEF and forced expiratory volume in 1 second (FEV1), inhaled corticosteroid adherence measured by electronic monitors, Asthma Control Test, and emergency health care use for asthma. Results: The sample comprised 354 children (mean = 13.2 ± 2.2 yr; 62% Latino, 38% Black) and caregivers. The PEF feedback group (N = 153 analyzed) demonstrated greater improvements at 1-month follow-up on underperception of airflow limitation (difference-in-differences, -12.64; 95% confidence interval [CI], -17.54 to -7.74), percent personal best PEF (9.89; 95% CI, 7.13 to 12.65), percent predicted FEV1 (4.93; 95% CI, 0.95 to 8.90), and inhaled corticosteroid adherence (16.02; 95% CI, 7.15 to 24.89) compared with the supportive counseling group (N = 152 analyzed). At 12-month follow-up, the PEF feedback group maintained improvements on underperception of airflow limitation (-13.87; 95% CI, -19.03 to -8.71), maintained higher percentage personal best PEF (14.23; 95% CI, 11.37 to 17.08) and percent predicted FEV1 (5.62; 95% CI, 1.56 to 9.67), and had smaller declines in inhaled corticosteroid adherence (17.51; 95% CI, 7.12 to 27.89) versus before intervention than the supportive counseling group. No between-group differences existed for asthma control or health care use. Conclusions: The efficacy and sustainability of PEF feedback was established in improving children's perception of airflow limitation, pulmonary function, and medication adherence. Clinical trial registered with www.clinicaltrials.gov (NCT02702687).

Evaluation and management of the critically ill adult asthmatic in the emergency department setting

INTRODUCTION

Asthma is a common reason for presentation to the Emergency Department and is associated with significant morbidity and mortality. While patients may have a relatively benign course, there is a subset of patients who present in a critical state and require emergent management.

OBJECTIVE

This narrative review provides evidence-based recommendations for the assessment and management of patients with severe asthma.

DISCUSSION

It is important to consider a broad differential diagnosis for the cause and potential mimics of asthma exacerbation. Once the diagnosis is determined, the majority of the assessment is based upon the clinical examination. First line therapies for severe exacerbations include inhaled short-acting beta agonists, inhaled anticholinergics, intravenous steroids, and magnesium. Additional therapies for refractory cases include parenteral epinephrine or terbutaline, helium‑oxygen mixture, and consideration of ketamine. Intravenous fluids should be administered, as many of these patients are dehydrated and at risk for hypotension if they receive positive pressure ventilatory support. Noninvasive positive pressure ventilation may prevent the need for endotracheal intubation. If mechanical ventilation is required, it is important to avoid breath stacking by setting a low respiratory rate and allowing permissive hypercapnia. Patients with severe asthma exacerbations will require intensive care unit admission.

CONCLUSIONS

This review provides evidence-based recommendations for the assessment and management of severe asthma with a focus on the emergency clinician.

Dyspnea Perception During Induced Bronchoconstriction Is Complicated by the Inhaled Methacholine in Children With Clinical Asthma

Purpose

Dyspnea is not widely utilized as an indicator of asthma provocation despite its universal presentation. We hypothesized that dyspnea severity was proportionate with the lung function decline, methacholine dose-step, and the degree of bronchial hyperresponsiveness (BHR).

Methods

We retrospectively analyzed 73 children's bronchial provocation test data with an assessment of dyspnea at every dose-step. Dyspnea severity was scored using a modified Borg (mBorg) scale. A linear mixed effect analysis was performed to evaluate the relationship between the mBorg scale, the percentage fall in the forced expiratory volume in 1 second (FEV1) (ΔFEV1%), the methacholine dose-step, and the degree of BHR (BHR grade).

Results

Subjects were divided into 5 BHR groups based on their last methacholine dose-steps. The mBorg scores did not differ significantly among BHR groups (P=0.596, Kruskal-Wallis test). The linear mixed effect analysis showed that ΔFEV1% was affected by the methacholine dose-step (P<0.001) and BHR grade (P<0.001). The mBorg score was affected by the dose-step (P<0.001) and BHR grade (P=0.019). We developed a model to predict the mBorg score and found that it was affected by the methacholine dose-step and ΔFEV1%, elevating it by a score of 0.039 (χ² [1]=21.06, P<0.001) and 0.327 (χ² [1]=47.45, P<0.001), respectively. A significant interaction was observed between the methacholine dose-step and ΔFEV1% (χ² [1]=16.20, P<0.001).

Conclusions

In asthmatic children, inhaled methacholine, as well as the degree of BHR and lung function decline, may affect dyspnea perception during the bronchial provocation test. If we wish to draw meaningful information from dyspnea perception, we have to consider various complicating factors underlying it.

The Perception of Asthma Severity in Children

The ability to perceive the onset and severity of symptoms of worsening asthma is important, not only for initial diagnosis but also for early identification of an asthma exacerbation and prompt management. There are subjective and objective methods for identifying symptoms. Symptom perception is affected by multiple mechanisms, and not all patients can accurately perceive symptoms of airflow limitation. Hyperperceivers will report substantial discomfort in the face of minimal bronchoconstriction, and poor perceivers will report no symptoms even in the presence of severe obstruction. The use of objective measures of airflow limitation is essential for such patients. Regimens for training perception in children and adults have been studied and are available.

Will symptom-based therapy be effective for treating asthma in children?

Traditionally, symptoms are important patient-oriented outcomes in asthma treatment, and assessment of symptoms is an essential component of assessing asthma control. However, variable airways obstruction, airways hyperresponsiveness and chronic inflammation are key components of the asthma syndrome, and correlations among these hallmarks and symptoms are weak or even absent. Therefore, it might be questioned if symptom-based therapy is effective for treating asthma in (all) children. To date, there is no firm indication that monitoring asthma based on repetitive lung function measurement or markers of airway inflammation is superior to monitoring based on symptoms only. In the majority of patients, symptom-based asthma management may well be sufficient, and in preschool children, symptoms are presently the only feasible outcome. Nevertheless, there is some evidence that selected groups might benefit from an approach that takes into account individual phenotypic characteristics. In patients with poor perception, those with a discordant phenotype and those with persistent severe asthma, considering lung function, airways hyperresponsiveness and inflammatory markers in treatment decisions might improve outcomes.

Perception of bronchodilation assessed by Visual Analogue Scale in children with asthma

BACKGROUND

Visual Analogue Scale (VAS) has been proposed as a useful tool for assessing the perception of asthma symptoms, a cornerstone in disease management. While airway flow limitation and its reversibility are thought to be a useful marker of disease severity, there are very few studies that evaluated the response to bronchodilation (BD) testing perception by VAS. To investigate whether VAS assessment of breathlessness perception could provide a useful tool to assess the response to BD testing in asthmatic children.

METHODS

This cross-sectional study included a total of 150 children (96 males, mean age 11.05 years) with asthma, 50 had bronchial obstruction (i.e. FEV1 <80% of predicted). Perception of breathlessness was assessed by VAS; lung function was measured by spirometry. BD testing was performed in all children.

RESULTS

In children with bronchial obstruction, VAS at baseline was 4.7 and significantly increased to 6.9 (p<0.001) after BD. In children without bronchial obstruction, VAS at baseline was 7.4, but further significantly increased to 8.4 after BD testing (p<0.01). There was a significant difference in Δ VAS between children with bronchial reversibility and children without it (p<0.0001).

CONCLUSIONS

The present study demonstrates that VAS might be considered an initial tool to assess the BD response in children with asthma, mainly with overt bronchial obstruction.

Perception of bronchoconstriction: a complementary disease marker in children with asthma

INTRODUCTION

Asthma guidelines use symptoms as the most important aspect of asthma control. Symptom perception varies widely between individuals. Over-perception as well as underperception of bronchoconstriction could have a negative effect on asthma management. We hypothesized that perception of bronchoconstriction in childhood asthma is not related to common measures of disease control. For that reason, we examined the clinical determinants of the perception of bronchoconstriction and the repeatability of perception measurements.

PATIENTS AND METHODS

In school-age children with moderately severe atopic asthma, we measured the perception of bronchoconstriction (decrease in forced expiratory volume in 1 second (FEV(1)) during methacholine bronchoprovocation challenges. The perception of bronchoconstriction was assessed as the slope of the relation between FEV(1) and Borg score, and as the Borg score at a 20% decrease in FEV(1) from baseline during the provocation test (PS(20)). Data from subjects who had a 20% or more decrease in FEV(1) (n = 112) were used for the analysis. Fifty-four children repeated the test after 3 months. Symptoms, use of rescue medication, and peak expiratory flows were scored in diaries during the 2 weeks before testing.

RESULTS

Symptom perception was significantly better in children without (PD(20) > 1570 μg, n = 28) than in children with airway hyperresponsiveness (PD(20) ≤ 1570 μg, n = 112), slope 0.22 versus 0.13 respectively (p < .001). Borg scores correlated with PD(20) (p = .01), baseline FEV(1) (only for slope, p = .04), and use of rescue beta agonist (p = .01), but not with other aspects of asthma control. Repeatability of Borg scores was good (slope: R = 0.59, PS(20): R = 0.52).

CONCLUSION

Poorer symptom perception in asthmatic children correlated with hyperresponsiveness, and was associated with lower baseline FEV(1) and less use of rescue bronchodilators. This suggests that the measurement of symptom perception should be taken into account in individual management plans for children with asthma.

Effects of exercise training on airway closure in asthmatics

We previously reported that responsiveness to methacholine (Mch) in the absence of deep inspiration (DI) decreased in healthy subjects after a short course of exercise training. We assessed whether a similar beneficial effect of exercise on airway responsiveness could occur in asthmatics. Nine patients (male/female: 3/6; mean age ± SD: 24 ± 2 yr) with mild untreated asthma [forced expiratory volume in 1 s (FEV(1)): 100 ± 7.4% pred; FEV(1)/vital capacity (VC): 90 ± 6.5%] underwent a series of single-dose Mch bronchoprovocations in the absence of DI in the course of a 10-wk training rowing program (6 h/wk of submaximal and maximal exercise), at baseline (week 0), and at week 5 and 10. The single-dose Mch was established as the dose able to induce ≥ 15% reduction in inspiratory vital capacity (IVC) and was administered to each subject at every challenge occasion. Five asthmatics (male/female: 1/4; mean age ± SD: 26 ± 3 yr) with similar baseline lung function (FEV(1): 102 ± 7.0% predicted; FEV(1)/VC: 83 ± 6.0%; P = 0.57 and P = 0.06, respectively) not participating in the exercise training program served as controls. In the trained group, the Mch-induced reduction in IVC from baseline was 22 ± 10% at week 0, 13 ± 11% at week 5 (P = 0.03), and 11 ± 8% at week 10 (P = 0.028). The Mch-induced reduction in FEV(1) did not change with exercise (P = 0.69). The reduction in responsiveness induced by exercise was of the same magnitude of that previously obtained in healthy subjects (50% with respect to pretraining). Conversely, Mch-induced reduction in IVC in controls remained unchanged after 10 wk (%reduction IVC at baseline: 21 ± 20%; after 10 wk: 29 ± 14%; P = 0.28). This study indicates that a short course of physical training is capable of reducing airway responsiveness in mild asthmatics.

Asthma outcomes: symptoms

BACKGROUND

Respiratory symptoms are commonly used to assess the impact of patient-centered interventions.

OBJECTIVE

At the request of National Institutes of Health (NIH) institutes and other federal agencies, an expert group was convened to propose which measurements of asthma symptoms should be used as a standardized measure in future clinical research studies.

METHODS

Asthma symptom instruments were classified as daily diaries (prospectively recording symptoms between research visits) or retrospective questionnaires (completed at research visits). We conducted a systematic search in PubMed and a search for articles that cited key studies describing development of instruments. We classified outcome instruments as either core (required in future studies), supplemental (used according to study aims and standardized), or emerging (requiring validation and standardization). This work was discussed at an NIH-organized workshop in March 2010 and finalized in September 2011.

RESULTS

Four instruments (3 daily diaries, 1 for adults and 2 for children; and 1 retrospective questionnaire for adults) were identified. Minimal clinically important differences have not been established for these instruments, and validation studies were only conducted in a limited number of patient populations. Validity of existing instruments may not be generalizable across racial-ethnic or other subgroups.

CONCLUSIONS

An evaluation of symptoms should be a core asthma outcome measure in clinical research. However, available instruments have limitations that preclude selection of a core instrument. The working group participants propose validation studies in diverse populations, comparisons of diaries versus retrospective questionnaires, and evaluations of symptom assessment alone versus composite scores of asthma control.

Predictive factors for airway hyperresponsiveness in children with respiratory symptoms

BACKGROUND

Asthma diagnosis is a challenging condition, particularly in patients without obstructive pattern and reversibility on spirometry. Determination of airway hyperresponsiveness (AHR) may be helpful, but the procedure is time-consuming and not always practical.

OBJECTIVE

To determine the potential factors that may predict the presence of AHR in children with asthmalike symptoms but without obstructive pattern and reversibility on spirometry.

METHODS

All patients with asthmalike symptoms but without obstructive pattern and reversibility on spirometry were analyzed retrospectively between January 9, 2007, and December 30, 2009. The features of clinical history and laboratory results were analyzed with univariate and multivariate regression analysis.

RESULTS

A total of 111 children between 6 and 18 years of age, with a median age of 10.2 years, were analyzed, and AHR was detected in 67 patients (60.3%). Multivariate logistic regression analysis revealed coexistence of nocturnal cough and exercise-induced cough (odds ratio [OR], 22.1; 95% confidence interval [CI], 3.1-159.2; P = .004), eosinophilia (OR, 18.7; 95% CI, 1.9-178.7; P = .01), and borderline bronchodilator response in forced expiratory volume in 1 second (between 7% and 11%) (OR, 10.1; 95% CI, 2.1-49.1; P = .004) as significant risk factors for the presence of AHR, whereas exercise-induced dyspnea was found to be related to the absence of AHR (OR, 0.2; 95% CI, 0.1-0.8; P = .02).

CONCLUSION

In children with asthmalike symptoms but with normal spirometry, certain features of clinical history and laboratory results can strongly predict the presence of AHR and may help less frequent use of challenge tests.