Spirometry in the diagnosis of asthma in children

Current Practices in Pediatric Asthma Care

This article is a comprehensive review of the latest knowledge and developments on pediatric asthma. It serves as a guide for general practitioners and subspecialists who treat asthma. The pathophysiology and critical features of asthma that should be addressed and the latest therapies available are discussed. The areas where further investigation is needed are also highlighted.

The role of respiratory syncytial virus- and rhinovirus-induced bronchiolitis in recurrent wheeze and asthma-A systematic review and meta-analysis

INTRODUCTION

Respiratory syncytial virus (RSV) is the most common cause of bronchiolitis. RSV-induced bronchiolitis has been associated with preschool wheeze and asthma in cohort studies where the comparison groups consist of healthy infants. However, recent studies identify rhinovirus (RV)-induced bronchiolitis as a potentially stronger risk factor for recurrent wheeze and asthma.

AIM

This systematic review and meta-analysis aimed to compare the associations of RSV- and RV-induced bronchiolitis with the development of preschool wheeze and childhood asthma.

METHODS

We performed a systematic search of the published literature in five databases by using a MeSH term-based algorithm. Cohort studies that enrolled infants with bronchiolitis were included. The primary outcomes were recurrent wheeze and asthma diagnosis. Wald risk ratios and odds ratios (ORs) were estimated, along with their 95% confidence intervals (CIs). Individual and summary ORs were visualized with forest plots.

RESULTS

There were 38 studies included in the meta-analysis. Meta-analysis of eight studies that had data on the association between infant bronchiolitis and recurrent wheeze showed that the RV-bronchiolitis group were more likely to develop recurrent wheeze than the RSV-bronchiolitis group (OR 4.11; 95% CI 2.24-7.56). Similarly, meta-analysis of the nine studies that had data on asthma development showed that the RV-bronchiolitis group were more likely to develop asthma (OR 2.72; 95% CI 1.48-4.99).

CONCLUSION

This is the first meta-analysis that directly compares between-virus differences in the magnitude of virus-recurrent wheeze and virus-childhood asthma outcomes. RV-induced bronchiolitis was more strongly associated with the risk of developing wheeze and childhood asthma.

The role of objective tests to support a diagnosis of asthma in children

In many healthcare settings asthma in children is a clinical diagnosis based on parental reported symptoms. These include intermittent episodes of wheezing, breathlessness and periodic nocturnal dry cough. Increased symptoms often coincide with colds. Confirming a diagnosis of asthma in children can be difficult and recent reports highlight that misdiagnosis, including over- and under-diagnosis of asthma are common. Recent UK National Institute of Health and Care Excellence guidelines recommend diagnostic algorithms for children from five years and adults to support a clinical suspicion of asthma. Spirometry, bronchodilator reversibility and fractional exhaled nitric oxide testing are the first line tests to diagnose asthma in children. The introduction of these tests across all healthcare settings has the potential to reduce misdiagnosis, improve asthma management and reduce healthcare spending for asthma.

Maximal flow at functional residual capacity in asthmatic preschool children

BACKGROUND

Many preschool children will perform correct peak-flow but will not exhale to residual volume, thus limiting the determination of airways obstruction. The maximal flow measured at function residual capacity (V'maxFRC) is independent of lung empting and could potentially serve as a parameter for describing flow at low lung volumes. The study determines the detection of airway obstruction/dilation in asthmatic preschool children by V'maxFRC, compared to FEV1 and FEF25-75.

METHODS

Children performed bronchial provocation test (BPT; n = 26) or received bronchodilators (Post-BD; n = 31). V'maxFRC was extracted at inspiratory capacity point of flow/volume maneuvers. The %change of V'maxFRC from baseline was compared with changes in various spirometry indices and to values obtained from our previously studied healthy control children.

RESULTS

FEV1, FEF25-75, and V'maxFRC decreased by 30.9 ± 12.2%, 46.2 ± 10.9%, and 36.6 ± 8.0%, respectively, while FRC increased by 37.0 ± 24.9% at end of the BPT. Post-BD spirometry values increased by 17.1 ± 16.1%, 47.0 ± 42.2, and 45 ± 24%, respectively (p < 0.0001). A positive response to bronchodilators was observed in 15/31 (48%) children by FEV1, in 22/31 (71%) children by V'maxFRC, and in 21/31 children by FEF25-75.

CONCLUSION

V'maxFRC detects airway obstruction/dilation in young asthmatic children similar to FEF25-75 and FEV1. V'maxFRC may be a valuable index in preschool children who cease exhalation prematurely. Digitally measured V'maxFRC should confirm the actual values in a wider age range in healthy and disease states.

Spirometry in children

Respiratory disorders are responsible for considerable morbidity and mortality in children. Spirometry is a useful investigation for diagnosing and monitoring a variety of paediatric respiratory diseases, but it is underused by primary care physicians and paediatricians treating children with respiratory disease. We now have a better understanding of respiratory physiology in children, and newer computerised spirometry equipment is available with updated regional reference values for the paediatric age group. This review evaluates the current literature for indications, test procedures, quality assessment, and interpretation of spirometry results in children. Spirometry may be useful for asthma, cystic fibrosis, congenital or acquired airway malformations and many other respiratory diseases in children. The technique for performing spirometry in children is crucial and is discussed in detail. Most children, including preschool children, can perform acceptable spirometry. Steps for interpreting spirometry results include identification of common errors during the test by applying acceptability and repeatability criteria and then comparing test parameters with reference standards. Spirometry results depict only the pattern of ventilation, which may be normal, obstructive, restrictive, or mixed. The diagnosis should be based on both clinical features and spirometry results. There is a need to encourage primary care physicians and paediatricians treating respiratory diseases in children to use spirometry after adequate training.

Urinary leukotriene excretion profile in children with exercise-induced asthma compared with controls: a preliminary study

BACKGROUND

Leukotrienes are among the most important mediators associated with inflammatory responses in patients with exercise induced asthma (EIA). The aim of this study was to investigate the impact of exercise on the urinary leukotriene profile. Hence, we compared post exercise changes of urinary leukotriene E4 (LTE4) concentration between children with EIA and healthy controls.

METHODS

Ten children with EIA and 15 controls were enrolled. Both groups underwent a standardised exercise challenge test (ECT). LTE4 concentration was measured in urine samples obtained pre and post ECT, using enzyme immunoassay and adjusted by urinary creatinine concentrations.

RESULTS

Median (minimum-maximum) pre ECT concentration of LTE4 was 17.82 (7.58-90.23 pg/ml) in EIA and 17.24 (4.64-64.02 pg/ml) in controls, p=0.86. LTE4 concentration post ECT were 23.37 (4.02-93.00 pg/ml) in EIA and 11.74 (0.13-25.09 pg/ml) in controls, p=0.02. Changes of LTE4 concentration post ECT were 2.54 (-31.98 to 43.31 pg/ml) in cases and -13.53 (-46.00 to 11.02 pg/ml) in controls, p=0.03. There was no significant correlation between basal predicted FEV(1) [%] and changes in LTE4 concentration in cases (i.e., r(s)=0.14) nor controls (i.e., r(s)=0.12). There was a tendency towards more pronounced changes in LTE4 concentration post ECT in children with moderate/mild persistent asthma compared to those with mild but intermittent asthma.

CONCLUSIONS

Children with EIA had significantly higher changes of urinary LTE4 concentrations post ECT compared to healthy controls. Urinary measurement of LTE4 may be an interesting and non-invasive option to assess control of EIA in children.

Assessment of inhaled corticosteroid treatment response in asthma using hypertonic histamine challenge-induced cough

BACKGROUND AND AIMS

Bronchial provocation tests may be utilised to monitor the efficacy of the corticosteroid treatment. Unfortunately, these measurements necessitate good patient cooperation during the spirometry. Coughing during such tests is related to the degree of the bronchoconstriction and occurs involuntarily, i.e. independent of patient cooperation. This study aimed to evaluate the utility of a hypertonic histamine challenge-induced cough in assessing the efficacy of inhaled corticosteroid treatment.

METHODS

A total of 16 steroid-naïve asthmatics and 10 non-asthmatic, symptomatic controls received 800-microg beclomethasone (Beclomet Easyhaler(R), Orion Ltd., Orion Pharma, Helsinki, Finland) via powder inhaler per day for 8 weeks. Videoed inhalation challenge with hypertonic histamine solution was performed before and after the treatment. Symptom questionnaire was completed before both challenges. The airway responsiveness to hypertonic histamine was expressed as the cumulative number of coughs divided by the final histamine concentration administered [coughs/concentration ratio (CCR)] and as the provocative concentration of histamine to induce a 20% fall in FEV(1)(PC(20)).

RESULTS

CCR [geometric mean; 95% confidence interval (CI)] of the asthmatic subjects decreased from 494 (209-1168) to 73.6 (29.8-182) coughs per mg/mL (P = 0.002). Their PC(20) levels were 1.31 (1.07-1.60) and 1.91 (1.33-2.74) mg/mL over the treatment period (P = 0.01). The symptom frequency also decreased significantly in the asthmatics (P = 0.039). There were no significant changes in PC(20) level, in CCR level or in symptom frequency in non-asthmatic subjects during the treatment.

CONCLUSIONS

Hypertonic histamine challenge-induced cough and PC(20) are sensitive measures in assessing the treatment effect in asthma. The cough response may be especially useful in subjects who cannot perform spirometry reliably.

Asthma symptoms in rural living Tanzanian children; prevalence and the relation to aerobic fitness and body fat

OBJECTIVE

To determine the prevalence of asthma symptoms in children from a rural district in North-Tanzania, and their relationship to aerobic fitness and body fat.

METHODS

In Manyara region in Tanzania, children (aged 9-10 years) were randomly selected to participate in the present cross-sectional study. Hundred and seventy two participants completed a video questionnaire showing the symptoms and signs of asthma. Lung function was measured by maximum forced expiratory flow-volume curves. Aerobic fitness was estimated from a standardized indirect maximal cycle ergometer test and sum of three skinfolds reflected body fat.

RESULTS

Twenty four per cent reported asthma symptoms last year. Severe wheezing attacks last year were reported in 5% of the participants. Thirty seven per cent of the participants were underweight. Underweight children had significantly lower (P < 0.02) lung function (per cent of predicted). Lower body fat was associated with higher occurrence of asthma symptoms (odds ratio and 95% CI; 0.45 (0.22-0.95; P = 0.04). Aerobic fitness was not associated with asthma symptoms.

CONCLUSIONS

More than every fifth 9-10 year old child from a rural district in North-Tanzania reported asthma symptoms. Lower body fat was associated with higher occurrence of asthma symptoms, but aerobic fitness was not associated with asthma symptoms.

Cough and dyspnea during bronchoconstriction: comparison of different stimuli

Background

Bronchial challenge tests are used to evaluate bronchial responsiveness in diagnosis and follow-up of asthmatic patients. Challenge induced cough has increasingly been recognized as a valuable diagnostic tool. Various stimuli and protocols have been employed. The aim of this study was to compare cough and dyspnea intensity induced by different stimuli.

Methods

Twenty asthmatic patients underwent challenge tests with methacholine, bradykinin and exercise. Cough was counted during challenge tests. Dyspnea was assessed by modified Borg scale and visual analogue scale. Statistical comparisons were performed by linear mixed-effects model.

Results

For cough evaluation, bradykinin was the most potent trigger (p < 0.01). In terms of dyspnea measured by Borg scale, there were no differences among stimuli (p > 0.05). By visual analogue scale, bradykinin induced more dyspnea than other stimuli (p ≤ 0.04).

Conclusion

Bradykinin seems to be the most suitable stimulus for bronchial challenge tests intended for measuring cough in association with bronchoconstriction.

Exhaled nitric oxide in childhood asthma: a review

As an 'inflammometer', the fraction of nitric oxide in exhaled air (Fe(NO)) is increasingly used in the management of paediatric asthma. Fe(NO) provides us with valuable, additional information regarding the nature of underlying airway inflammation, and complements lung function testing and measurement of airway hyper-reactivity. This review focuses on clinical applications of Fe(NO) in paediatric asthma. First, Fe(NO) provides us with a practical tool to aid in the diagnosis of asthma and distinguish patients who will benefit from inhaled corticosteroids from those who will not. Second, Fe(NO) is helpful in predicting exacerbations, and predicting successful steroid reduction or withdrawal. In atopic asthmatic children Fe(NO) is beneficial in adjusting steroid doses, discerning those patients who require additional therapy from those whose medication dose could feasibly be reduced. In pre-school children Fe(NO) may be of help in the differential diagnosis of respiratory symptoms, and may potentially allow for better targeting and monitoring of anti-inflammatory treatment.