Airway resistance measurements in pre-school children with asthmatic symptoms: the interrupter technique

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.

Priorities for future research into asthma diagnostic tools: A PAN-EU consensus exercise from the European asthma research innovation partnership (EARIP)

The diagnosis of asthma is currently based on clinical history, physical examination and lung function, and to date, there are no accurate objective tests either to confirm the diagnosis or to discriminate between different types of asthma. This consensus exercise reviews the state of the art in asthma diagnosis to identify opportunities for future investment based on the likelihood of their successful development, potential for widespread adoption and their perceived impact on asthma patients. Using a two-stage e-Delphi process and a summarizing workshop, a group of European asthma experts including health professionals, researchers, people with asthma and industry representatives ranked the potential impact of research investment in each technique or tool for asthma diagnosis and monitoring. After a systematic review of the literature, 21 statements were extracted and were subject of the two-stage Delphi process. Eleven statements were scored 3 or more and were further discussed and ranked in a face-to-face workshop. The three most important diagnostic/predictive tools ranked were as follows: "New biological markers of asthma (eg genomics, proteomics and metabolomics) as a tool for diagnosis and/or monitoring," "Prediction of future asthma in preschool children with reasonable accuracy" and "Tools to measure volatile organic compounds (VOCs) in exhaled breath."

Diagnostic accuracy of capnovolumetry for the identification of airway obstruction - results of a diagnostic study in ambulatory care

BACKGROUND

One of the known weaknesses of spirometry is its dependence on patients' cooperation, which can only partially be alleviated by educational efforts. Therefore, procedures less dependent on cooperation might be of value in clinical practice. We investigated the diagnostic accuracy of ultrasound-based capnovolumetry for the identification of airway obstruction.

METHODS

Consecutive patients from a pulmonary outpatient clinic were included in the diagnostic study. As reference standard, the presence of airway obstruction was evaluated via spirometry and bodyplethysmography. Capnovolumetry was performed as index test with an ultrasound spirometer providing a surrogate measure of exhaled carbon dioxide. Receiver operating characteristic (ROC) analysis was performed using the ratio of slopes of expiratory phases 3 and 2 (s3/s2) ≥ 0.10 as primary capnovolumetric parameter for the recognition of airway obstruction. Logistic regression was performed as secondary analysis to identify further useful capnovolumetric parameters. The diagnostic potential of capnovolumetry to identify more severe degrees of airway obstruction was evaluated additionally.

RESULTS

Of 1400 patients recruited, 1287 patients were included into the analysis. Airway obstruction was present in 29% of patients. The area under the ROC-curve (AUC) of s3/s2 was 0.678 (95% CI 0.645, 0.710); sensitivity of s3/s2 ≥ 0.10 was 47.7 (95% CI 42.7, 52.8)%, specificity 79.0 (95% CI 76.3, 81.6)%. When combining this parameter with three other parameters derived from regression analysis (ratio area/volume phase 3, slope phase 3, volume phase 2), an AUC of 0.772 (95% CI 0.743, 0.801) was obtained. For severe airway obstruction (FEV₁ ≤ 50% predicted) sensitivity of s3/s2 ≥ 0.10 was 75.9 (95% CI 67.1, 83.0)%, specificity 75.8 (95% CI 73.3, 78.1)%; for very severe airway obstruction (FEV₁ ≤ 30% predicted) sensitivity was 86.7 (95% CI 70.3, 94.7)%, specificity 72.8 (95% CI 70.3, 75.2)%. Sensitivities increased and specificities decreased considerably when the combined capnovolumetric score was used as index test.

CONCLUSIONS

Capnovolumetry by way of an ultrasound spirometer had a statistically significant albeit moderate potential for the recognition of airway obstruction in a heterogeneous population of patients typically found in clinical practice. Diagnostic accuracy of the capnovolumetric device increased with the severity of airway obstruction.

TRIAL REGISTRATION

The study is registered under DRKS00013935 at German Clinical Trials Register (DRKS).

Tools in Asthma Evaluation and Management: When and How to Use Them?

The goals of asthma management are accurate diagnosis, prompt initiation of treatment and monitoring of disease progression to limit potential morbidity and mortality. While the diagnosis and management is largely based on history taking and clinical examination, there are an increasing number of tools available that could be used to aid diagnosis, define phenotypes, monitor progress and assess response to treatment. Tools such as the Asthma Predictive Index could help in making predictions about the possibility of asthma in childhood based on certain clinical parameters in pre-schoolers. Lung function measurements such as peak expiratory flow, spirometry, bronchodilator responsiveness, and bronchial provocation tests help establish airway obstruction and variability over time. Tools such as asthma questionnaires, lung function measurements and markers of airway inflammation could be used in combination with clinical assessments to assess ongoing asthma control. Recent advances in digital technology, which open up new frontiers in asthma management, need to be evaluated and embraced if proven to be of value. This review summarises the role of currently available tools in asthma diagnosis and management. While many of the tools are readily available in resource rich settings, it becomes more challenging when working in resource poor settings. A rational approach to the use of these tools is recommended.

Asthma in childhood

Several topics on childhood asthma were addressed in the Paediatric Clinical Year in Review session at the 2015 European Respiratory Society International Congress. With regard to the relationship between lower respiratory tract infections and asthma, it emerges that is the number of respiratory episodes in the first years of life, but not the particular viral trigger, to be associated with later asthma development. Understanding which characteristics of individual patients are associated with an increased risk for asthma exacerbation is a critical step to implement strategies preventing these seasonal events. Recent data suggest the possibility that exhaled volatile organic compounds may qualify as biomarkers in detecting early signs of asthma. Adding information of exhaled volatile organic compounds and expression of inflammation genes to a clinical tool significantly improves asthma prediction in preschool wheezy children. Personal communication with children and adolescents is likely more important than the tools actually used for monitoring asthma. Systemic corticosteroids do not affect the long-term prognosis in children with first viral-induced wheezing episode and should be used cautiously during acute episodes. Finally, stress and a polymorphism upstream of a specific gene are both associated with reduced bronchodilator response in children with asthma.

25-Hydroxyvitamin D concentrations, asthma and eczema in childhood: The generation R study

BACKGROUND & AIMS

A role of vitamin D in the development of respiratory and allergic disease in children remains unclear. It may be likely that vitamin D has an effect on airway inflammation, but only few studies examined the effect in children. We aimed to examine whether serum 25-hydroxyvitamin D (25(OH) vitamin D) concentrations are associated with the fraction of exhaled nitric oxide (FeNO), airway interrupter resistance (Rint), physician diagnosed asthma ever, wheezing and eczema in a population-based cohort study in 6 year old children.

METHODS

Serum 25(OH) vitamin D concentration was assessed in 3815 children. 25(OH) vitamin D concentrations ≥75 nmol/L were considered as sufficient, between 50 and 75 nmol/L as insufficient, and <50 nmol/L as deficient. FeNO and Rint were measured at the research center. Data on physician diagnosed asthma, wheezing, and eczema were obtained by parent-reported questionnaires.

RESULTS

In comparison with sufficient 25(OH) vitamin D concentration, deficient concentrations were associated with elevated FeNO of ≥25 ppb (OR: 2.54; 95% CI: 1.34-4.80). In addition, deficient and insufficient 25(OH) vitamin D concentrations were associated with a lower Rint (Z-score: -1.26; 95% CI: -1.66 to -0.85) (ß: -0.75; 95% CI: -1.08 to -0.42), and increased risks of eczema (OR: 1.65; 95% CI: 1.13-2.41) (OR: 1.44; 95% CI: 1.06-1.95). Insufficient 25(OH) vitamin D concentration were associated with a decreased risk of physician diagnosed asthma ever (OR: 0.59; 95% CI: 0.38-0.94).

CONCLUSIONS

Our results indicate that lower 25(OH) vitamin D levels are associated with elevated FeNO levels, but lower Rint values. Lower 25(OH) vitamin D levels are also associated with a decreased risk for asthma diagnoses but an increased risk for eczema.

The association between maternal psychological stress and inflammatory cytokines in allergic young children

Background. Previous studies have shown that psychological stress is linked to asthma prevalence. Parental psychological stress may potentially influence inflammatory responses in their allergic children. The purpose of this study is to clarify the association between maternal psychological status and inflammatory response of allergic young children.

Methods. The study subjects were 152 young allergic children (median age: 13 months) who had not shown any allergic symptoms in the past one month. mRNA expression levels of the inflammatory response genes IL-6, IL-8, IL-10 and IL-22 were quantified by qRT-PCR. Maternal psychological status was assessed by standardized questionnaires: the Centre for Epidemiological Studies Depression Scale (CES-D) for depression and the Japanese Perceived Stress Scale (JPSS) for perceived stress.

Results. A significant positive association was observed between maternal CES-D scores and IL-6 mRNA expression in the children with asthma. The JPSS scores were also positively associated with IL-8 mRNA expression in asthmatic children and IL-6 mRNA expression in children with allergic rhinitis. Similar trends were observed among children positive for house dust mite-specific IgE, but these associations were not significant.

Conclusion. This study supports the hypothesis that maternal psychological stress affects the inflammatory response in their allergic children.

Exhaled biomarkers and gene expression at preschool age improve asthma prediction at 6 years of age

RATIONALE

A reliable asthma diagnosis is difficult in wheezing preschool children.

OBJECTIVES

To assess whether exhaled biomarkers, expression of inflammation genes, and early lung function measurements can improve a reliable asthma prediction in preschool wheezing children.

METHODS

Two hundred two preschool recurrent wheezers (aged 2-4 yr) were prospectively followed up until 6 years of age. At 6 years of age, a diagnosis (asthma or transient wheeze) was based on symptoms, lung function, and asthma medication use. The added predictive value (area under the receiver operating characteristic curve [AUC]) of biomarkers to clinical information (assessed with the Asthma Predictive Index [API]) assessed at preschool age in diagnosing asthma at 6 years of age was determined with a validation set. Biomarkers in exhaled breath condensate, exhaled volatile organic compounds (VOCs), gene expression, and airway resistance were measured.

MEASUREMENTS AND MAIN RESULTS

At 6 years of age, 198 children were diagnosed (76 with asthma, 122 with transient wheeze). Information on exhaled VOCs significantly improved asthma prediction (AUC, 89% [increase of 28%]; positive predictive value [PPV]/negative predictive value [NPV], 82/83%), which persisted in the validation set. Information on gene expression of toll-like receptor 4, catalase, and tumor necrosis factor-α significantly improved asthma prediction (AUC, 75% [increase of 17%]; PPV/NPV, 76/73%). This could not be confirmed after validation. Biomarkers in exhaled breath condensate and airway resistance (pre- and post- bronchodilator) did not improve an asthma prediction. The combined model with VOCs, gene expression, and API had an AUC of 95% (PPV/NPV, 90/89%).

CONCLUSIONS

Adding information on exhaled VOCs and possibly expression of inflammation genes to the API significantly improves an accurate asthma diagnosis in preschool children. Clinical trial registered with www.clinicaltrial.gov (NCT 00422747).

Respiratory disease and respiratory physiology: putting lung function into perspective: paediatric asthma

Dealing with paediatric asthma in daily practice, we are mostly interested in the airway function: the hallmark of asthma is the variability of airway patency. Various pulmonary function tests (PFT) can be used to quantify airway caliber in asthmatic children. The choice of the test is based on the developmental age of the child, knowledge of the diagnosis/underlying pathophysiology, clinical questions and reasoning, and treatment. PFT is performed to monitor the severity of asthma and the response to therapy, but can also be used as a diagnostic tool, and to study growth and development of the lungs and airways. This review aims to provide clinicians an overview of the differences in assessing PFT in infants and preschool children compared with older cooperative children, which tests are feasible in infants and young children, the limitations of and usefulness of these tests, and of their interpretation in these age groups.

Elevated inflammatory markers at preschool age precede persistent wheezing at school age

BACKGROUND

  Wheeze is a heterogeneous symptom in preschool children. At preschool age it is hard to predict whether symptoms will pass or persist and develop into asthma. Our objective is to prospectively study whether inflammatory markers in exhaled breath condensate (EBC) and pre- and post-bronchodilator interrupter resistance (Rint) assessed at preschool age, are associated with wheezing phenotypes at school age.

METHODS

  Children (N = 230) were recruited from the Asthma DEtection and Monitoring (ADEM) study. At preschool age [mean (SE): 3.3 (0.1) yr], pre- and post-bronchodilator Rint was assessed. EBC was collected using a closed glass condenser. Inflammatory markers (IL-2, IL-4, IL-8, IL-10, sICAM) were measured using multiplex immunoassay. Wheezing phenotypes at 5 yr of age were determined based on longitudinal assessment. Children were classified as: never (N = 47), early-transient (N = 89) or persistent wheezers (N = 94).

RESULTS

  Persistent wheezers had elevated levels of all interleukins at preschool age compared to children who never wheezed (p < 0.05). EBC markers did not differ between the persistent and transient wheezers. There was no marked difference in Rint between wheezing phenotypes.

CONCLUSIONS

  We demonstrated that 5 yr old children with persistent wheeze already had elevated exhaled inflammatory markers at preschool age compared to never wheezers, indicating augmented airway inflammation in these children.

Fluticasone or montelukast for preschool children with asthma-like symptoms: Randomized controlled trial

RATIONALE

Beneficial effects of anti-inflammatory therapy such as fluticasone propionate (FP) and montelukast (Mk) have been demonstrated in preschool children with asthma. However, comparative studies are lacking in this age group. Therefore, we conducted a study to evaluate and compare the effect of FP and Mk in preschool children with asthma-like symptoms.

METHODS

In this multicenter, randomized, placebo-controlled, double-blind, double-dummy trial, children aged 2-6 years with asthma-like symptoms were included. In total, 63 children were randomly allocated to receive FP (25), Mk (18) or placebo (20) for 3 months. The primary outcome was the daily symptom score (wheeze, cough, shortness of breath) as recorded by caregivers in a symptom diary card. Secondary endpoints were rescue medication free days, blood eosinophils and lung function (interrupter technique and forced oscillation technique (FOT)).

RESULTS

During the 3 months study period, symptoms improved in all 3 groups, with a statistically significant difference between FP and placebo in favor of the FP group (p=0.021). A significant reduction in circulating eosinophils after 3 months of treatment was found in the Mk group only (p=0.008), which was significantly different from the change found in the placebo group (p=0.045). With the exception of frequency dependence (measured by FOT), which showed a difference between FP and Mk after 3 months of treatment in favor of the FP group (p=0.048), no differences in lung function within or between groups were found.

CONCLUSIONS

In spite of a lack of power, our results suggest that FP has a beneficial effect on symptoms and Mk on blood eosinophil level as compared to placebo. Except for a difference in one lung function parameter after 3 months between FP and Mk in favor of the FP group, this study revealed no differences between FP and Mk.