Variations in exhaled nitric oxide in children with asthma during a 1-week stay in a mountain village sanatorium

Association Between Bedroom Particulate Matter Filtration and Changes in Airway Pathophysiology in Children With Asthma

Importance

Fine particles (particulate matter 2.5 μm [PM2.5]), a ubiquitous air pollutant, can deposit in the small airways that play a vital role in asthma. It appears to be unknown whether the use of a PM2.5 filtration device can improve small airway physiology and respiratory inflammation in children with asthma.

Objective

To discover what pathophysiological changes in the small airways are associated with using a PM2.5-removing device in the bedrooms of children with asthma.

Design, Setting, and Participants

Children with mild or moderate asthma were enrolled in this double-blind, crossover study. The participants used a true filtration device and a sham filtration device in their bedrooms in a random order for 2 weeks each with a 2-week washout interval. The study was conducted in a suburb of Shanghai, China, during a low-ozone season.

Exposures

Ozone and PM2.5 were measured inside bedrooms and outside a window.

Main Outcomes and Measures

Impulse oscillometry, spirometry, and fractional exhaled nitric oxide were measured at the beginning and the end of each intervention. Peak expiratory flow was measured twice daily at home.

Results

Forty-three children (5-13 years old; 26 boys [60%]) participated. Outdoor 24-hour mean PM2.5 concentrations were moderately high, ranging from 28.6 to 69.8 μg/m3 (median, 53 μg/m3). During true filtration, bedroom PM2.5 concentrations were a mean (SD) of 63.4% (35.9%) lower than during sham filtration. Compared with sham filtration, true filtration was significantly associated with improved airway mechanics, reflected in a 24.4% (95% CI, 11.8%-37.1%) reduction in total airway resistance, a 43.5% (95% CI, 13.7%-73.3%) reduction in small airway resistance, a 22.2% (95% CI, 2.2%-42.2%) reduction in resonant frequency, and a 73.1% (95% CI, 0.3%-145.8%) increase in airway reactance. True filtration was also associated with significant improvements in fractional exhaled nitric oxide (a 27.6% [95% CI, 8.9%-42.4%] reduction) and peak expiratory flow (a 1.6% [95% CI, 0.8%-2.5%] increase). These improvements were significantly associated with bedroom PM2.5 reduction. Improvements in small airway function were nonsignificant (8.4% [95% CI, -1.4% to 18.3%]) in all participants but significant (13.2% [95% CI, 1.2%-25.1%]) in participants without eosinophilic airway inflammation at baseline. No improvements were observed for forced vital capacity, forced expiratory volume during the first second, and the ratio of these in all participants or subgroups.

Conclusions and Relevance

Per these results, indoor PM2.5 filtration can be a practical method to improve air flow in an asthmatic lung through improved airway mechanics and function as well as reduced inflammation. This warrants a clinical trial to confirm.

Trial Registration

ClinicalTrials.gov Identifier: NCT03282864.

What is a clinically meaningful change in exhaled nitric oxide for children with asthma?

INTRODUCTION

Fractional exhaled nitric oxide (F_E NO) may be a useful objective measurement to guide asthma treatment. What remains uncertain is what change in F_E NO is clinically significant.

METHODS

An individual patient data analysis was performed using data from seven randomized clinical trials which used F_E NO to guide asthma treatment. The absolute and percentage intra-subject change in F_E NO measurements over "stable" and also "unstable" 3-month periods were described.

RESULTS

Data were available in 1112 randomized controlled trial participants and ≥1 stable period was present for 665 individuals. The interquartile range (IQR) and limits of agreement (LoA) for change in absolute F_E NO among individuals whose initial F_E NO was <50 parts per billion (ppb) were -7 to +9 ppb and -43 to +50 ppb, and for those with initial F_E NO ≥50 ppb IQR was -29 to +17 ppb and LoA was -80 to +76 ppb. For percentage change in F_E NO, the IQR and LoA for individuals whose initial F_E NO was <50 ppb were -33% to +51% and -157% to +215%, and for those with initial F_E NO ≥50 ppb were -33% to +35% and -159% to +192%. The variation in F_E NO values for a stable period was similar irrespective of whether it was followed by a stable or unstable period.

CONCLUSIONS

Over a 3-month period where F_E NO is initially <50 ppb, a rise of <10 ppb or of <50% (based on IQR) is unlikely to be related to asthma. When F_E NO is initially ≥50 ppb an percentage change of <50% (based on IQR) is unlikely to be asthma-related.

Multidisciplinary treatment in children with problematic severe asthma: A prospective evaluation

OBJECTIVE

For children with problematic severe asthma, achieving adequate control of asthma is difficult. The aim of this prospective observational study was to evaluate the effects of intensive multidisciplinary inpatient treatment on multiple outcome variables in children with problematic severe asthma.

METHODS

Participants were 89 children with problematic severe asthma (mean age 13.6 ± 2.5 years) treated in tertiary care clinics at high altitude (Switzerland) or sea level (Netherlands) and their parents (85 mothers, 55 fathers). The primary outcome variable was the Childhood Asthma Control Test (C-ACT). Other outcome variables were forced expiratory volume in 1 sec (FEV₁ ), fractional concentration of exhaled nitric oxide (FeNO), quality of life [PAQLQ(S)], children's coping (UCL-A), parents' report of behavioral problems (CBCL), and parenting stress (PSI/NOSI). Evaluations were taken pre-treatment, post-treatment, and 3-6 months follow-up. Median [P25;P75] treatment duration 74 [56;80] days; Median follow-up interval 131 [103;177] days.

RESULTS

The percentages of children showing controlled asthma (C-ACT) were 18% (pre-treatment), 69% (post-treatment), and 44% (follow-up). The vast majority of the children (80%) showed an improvement on C-ACT with 4% showing a deterioration. On C-ACT, FeNO, quality of life, and behavioral problems, improvements at post-treatment were highly significant. Improvements generally remained at a functional level at follow-up. Children's coping and parenting stress in parents did not change.

CONCLUSIONS

The improvement in asthma control and other outcome variables suggests that multidisciplinary inpatient treatment is an effective approach for a heterogeneous group of children with asthma that remained uncontrolled in secondary care. Pediatr Pulmonol. 2017;52:588-597. © 2016 Wiley Periodicals, Inc.

Reference values and factors associated with exhaled nitric oxide: U.S. youth and adults

BACKGROUND

Normative values for fractional exhaled nitric oxide (FeNO) and the associated co-factors are important in understanding the role of FeNO as a biomarker in airway disease. The objective of this study is to establish reference FeNO values for youth and adult asymptomatic, lifetime nonsmokers in the United States, and to describe the factors affecting these levels.

METHODS

Cross-sectional analyses of the National Health and Nutrition Examination Survey from 2007 to 2010. The analytic sample consisted of 4718 youth and adults, ages 6-79 years, who were lifelong nonsmokers, and free of asthma, and other respiratory conditions and symptoms. Loge FeNO values were used as dependent variables to test associations of demographic and health related-covariates. Multivariable regression models were used to assess the independent effect and covariate-adjusted contribution of the factors.

RESULTS

The geometric mean FeNO level was 8.3, 12.1, and 16.2 ppb for males 6-11, 12-19, and 20-79 years, and 8.4, 10.9, and 12.6 ppb for females in the corresponding age groups. Overall, FeNO levels increased with increasing age (p < 0.001), and height (p < 0.001). In all age groups, FeNO levels were positively associated with eosinophil counts, and with testing in the morning. Among youths 6-11 and 12-19 years, non-Hispanics whites had lower FeNO values than non-Hispanic blacks and Hispanic youths. No race-ethnic difference in FeNO levels was evident for adults 20-79 years. Among adolescents and adults, FeNO levels were higher for males than for females, controlling for all other factors.

CONCLUSIONS

These reference values and associated attributes in youths and adults are useful in evaluating the role of FeNO in airway diseases.

Does a parent-reported history of pneumonia increase the likelihood of respiratory symptoms needing therapy in asthmatic children and adolescents?

BACKGROUND

Asthmatic children and adolescents attending outpatient clinics often have a history of pneumonia. Whether respiratory symptoms, lung function, and airway inflammation differ in asthmatic patients with and without a history of pneumonia remains controversial.

AIMS

To compare clinical, lung functional, and inflammatory variables in asthmatic outpatients with and without a history of pneumonia. Methods. In 190 asthmatic outpatients, aged 6-18 years, we assessed respiratory symptoms, lung function (flows, volumes, and pulmonary diffusion capacity, DLCO/VA), and atopic-airway inflammation as measured by the fractional concentration of exhaled nitric oxide (FE(NO)). A previous medical and radiological diagnosis of pneumonia was defined as "recurrent pneumonia" if subjects had at least three pneumonia episodes or two episodes within a year.

RESULTS

Of the 190 outpatients studied, 38 (20%) had a history of pneumonia. These patients had more frequent upper-respiratory symptoms, nighttime awakenings in the past 4 weeks, daily use of inhaled corticosteroids, and lower FE(NO) than the 152 asthmatic children without previous pneumonia (FE(NO): 20.6 ppb, 95% CI: 15.2-28.0 vs. 31.1 ppb, 95% CI: 27.0-35.8; p < .05). Of the 38 patients with previous pneumonia, 14 had recurrent pneumonia. Despite comparable lung volumes and flows, they also had lower DLCO/VA than asthmatic children with no recurrent pneumonia and asthmatic children without previous pneumonia (DLCO/VA%: 91.2 ± 11.3 vs. 108.5 ± 14.7 vs. 97.9 ± 18.6, p < .05).

CONCLUSION

Respiratory assessment in asthmatic children and adolescents with a history of pneumonia, especially recurrent pneumonia, often discloses symptoms needing corticosteroid therapy, and despite normal lung volumes and flows, mild reductions in the variables reflecting gas diffusion and atopic-airway inflammation (DLCO/VA and FE(NO)). Whether these respiratory abnormalities persist in adulthood remains an open question.

Behavioral problems in children and adolescents with difficult-to-treat asthma

BACKGROUND

The aim of this study was to quantify behavioral problems in clinically treated children and adolescents with asthma and to examine the association of these problems and quality of life with difficult-to-treat asthma.

METHODS

Clinical patients with difficult-to-treat asthma (n = 31) and patients with asthma who were not classified as difficult-to-treat asthma (n = 52) completed the Pediatric Asthma Quality of Life Questionnaire [PAQLQ(S)]. Their parents completed the Child Behavior Checklist (CBCL) to assess behavioral problems. Behavioral problem scores were compared to norms of population reference groups and both behavioral problems and quality of life were compared between children and adolescents with and without difficult-to-treat asthma.

RESULTS

Especially internalizing behavioral problems such as being withdrawn/depressed and somatic complaints were more severe in the asthmatic groups compared to the healthy reference groups. The behavioral problems 'somatic complaints' and 'thought problems' as well as a lower quality of life were more severe in children and adolescents with difficult-to-treat asthma than in asthma patients who did not fulfill the criteria of difficult-to-treat asthma.

CONCLUSIONS

Behavioral problems and a lower quality of life are suggested to be more pronounced in clinically treated children and adolescents with difficult-to-treat asthma than in asthma patients who are not classified as difficult-to-treat asthma. With respect to practical implications, our data suggest that health-care professionals should - especially in children and adolescents with difficult-to-treat asthma - assess and, if necessary, treat behavioral problems.