Acceptability, reproducibility, and sensitivity of forced expiratory volumes and peak expiratory flow during bronchial challenge testing in asthmatic children

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.

Lung function, airway remodeling, and inflammation in infants: outcome at 8 years

BACKGROUND

Associations between early deficits of lung function, infant airway disease, and outcome at school age in symptomatic infants are still unclear.

OBJECTIVE

To report follow-up data on a unique cohort of children investigated invasively in infancy to determine predictive value of airway disease for school-aged respiratory outcomes.

METHODS

Fifty-three infants previously studied using bronchoscopy and airway conductance were approached at 8 years of age. Symptoms, lung volumes, and airway responsiveness were reassessed. Data on lifetime purchase of asthma medication were obtained. Lung function was compared with that of 63 healthy nonasthmatic children.

RESULTS

Forty-seven children were reevaluated. Physician-diagnosed asthma was present in 39 children (83%). Twenty-five children (53%) had current and 14 children (30%) had past asthma. No pathologic feature in infancy correlated with any outcome parameter. As expected, study children had significantly reduced lung function and increased airway responsiveness compared with healthy controls, and very early symptoms were risk factors for reduced lung function. Current asthma was associated with reduced infant lung function and parental asthma. Reduced lung function in infancy was associated with purchase of inhaled corticosteroids when 6 to 8 and 0 to 8 years of age.

CONCLUSION

The lack of predictive value of any pathologic measure in infancy, reported here for the first time to our knowledge, demonstrates that pathologic processes determining the inception of asthma, which are as yet undescribed, are different from the eosinophilic inflammation associated with ongoing disease.

Very low birth weight and respiratory outcome: association between airway inflammation and hyperresponsiveness

BACKGROUND

The respiratory outcomes after preterm birth have changed, and it is unclear whether increased airway hyperresponsiveness (AHR) later in childhood is associated with airway inflammation.

OBJECTIVE

To investigate the association between AHR and fractional exhaled nitric oxide (FeNO), including the alveolar concentration of nitric oxide, in school-age children with very low birth weight (VLBW).

METHODS

Twenty-nine children with VLBW, 33 children with a history of early wheeze, and 60 healthy controls underwent a FeNO measurement and bronchial challenge test with histamine. Atopy was assessed with skin prick tests.

RESULTS

Children with VLBW had well-preserved baseline lung function but significantly increased AHR, expressed as the dose response slope (P < .001). Geometric mean FeNO levels were similar between VLBW children and healthy controls, and a history of bronchopulmonary dysplasia had no effect. In the VLBW and early wheeze groups, AHR was associated with FeNO (r = 0.47, P = .01, and r = 0.43, P = .013, respectively), but in a stratified analysis, this association was significant only in atopic individuals. By using the multiple flow FeNO technique, the bronchial nitric oxide flux rather than alveolar nitric oxide concentrations were associated with AHR in both children with early wheeze and VLBW.

CONCLUSION

We conclude that in VLBW children AHR is related to FeNO but only in atopic individuals. Similar to children with early wheeze, this association is dependent on bronchial flux rather than alveolar nitric oxide concentration. It is likely that AHR is modified by atopic inflammation rather than by inflammatory process due to prematurity.

Cow's milk allergy as a predictor of bronchial hyperresponsiveness and airway inflammation at school age

BACKGROUND

Cow's milk allergy (CMA) has been found to be associated with an increased incidence of asthma at school age. However, prospective population-based studies of CMA and the development of airway inflammation and bronchial hyperresponsivess (BHR) are lacking.

OBJECTIVE

The aims of this study was to evaluate CMA as a risk factor for BHR and airway inflammation presented later in childhood.

METHODS

We followed prospectively 118 children with CMA and invited them to a clinical visit at a mean age of 8.6 years including the measurement of exhaled nitric oxide (FE(NO) ) and bronchial challenge with histamine. Ninety-four patients and 80 control subjects from the same cohort participated.

RESULTS

At school age, children with a history of CMA had higher FE(NO) levels (P=0.0009) and more pronounced responsiveness to histamine (P=0.027) than their controls. Stratified analysis showed a significant difference only in IgE-positive CMA. Multinomial logistic regression analysis showed that IgE-positive CMA [odds ratio (OR) 3.51; 95% confidence intervals (CI) 1.56-7.90; P=0.002] and a history of wheeze during the first year of life (OR 2.81; 95% CI 1.16-6.84; P=0.023) were independent explanatory factors for increased FE(NO) , and IgE-positive CMA (OR 3.37; 95% CI 1.03-10.97; P=0.044) and parental smoking (OR 3.41; 95% CI 1.14-10.22; P=0.028) for increased BHR, whereas for IgE-negative CMA, no associations with FE(NO) or BHR were found. In the CMA group, those exposed to CM very early at the maternity hospital, had less BHR (P=0.002).

CONCLUSIONS

Compared with their controls, children with a history of IgE-positive CMA show signs of airway inflammation, expressed as higher FE(NO) , and more pronounced bronchial responsiveness to histamine at school age. In contrast to IgE-negative CMA, IgE-positive CMA is a significant predictor of increased FE(NO) and BHR at school age. Very early exposure to CM was associated with less BHR.

Levosalbutamol vs racemic salbutamol in the treatment of acute exacerbation of asthma

OBJECTIVE

To compare efficacy and tolerability of levosalbutamol (Group 1) and racemic salbutamol (Group 2) for the treatment of acute exacerbation of asthma in children age 5 to 18 yr.

METHODS

A randomized double blind clinical study involving 60 children was undertaken between October' 06 to December' 07.

RESULTS

The following baseline clinical characteristic were recorded initially and after giving 3 nebulizations at 20 min intervals in the Ist hour of presentation viz respiratory rate (RR), heart rate (HR), oxygen saturation in room air SPO2, PEFR (peak expiratory flow rate), serum K+ level and asthma score. In Group 1 patients (levosalbutamol), there was significant increment in SPO2 and PEFR (P<0.05) values with decrease in tachypnea and asthma score while no significant difference was found in pre and post treatment HR & Serum K+ levels. In Group 2 patients although there was clinical improvement in terms of SPO2, PEFR, RR and asthma score, it resulted in significant tachycardia and decrease in K+ levels.

CONCLUSION

Levosalbutamol appears to be more efficacious than racemic salbutamol in terms of improvement in PEFR, SPO2 and asthma score while deleterious effects of tachycardia and fall in serum K+ were seen with racemic salbutamol.

[Variability in peak expiratory flow does not classify asthma according to severity]

OBJECTIVE

The aim of this study was to determine whether variability in peak expiratory flow (PEF) could be used to classify the level of severity of asthma in children.

PATIENTS AND METHODS

We studied 387 boys and girls diagnosed with asthma and classified severity according to clinical criteria (Spanish Society of Pediatric Pneumology). PEF variability was determined using a portable mini-Wright peak flow meter (Clement Clarke International, London, UK; range, 50 L/min-800 L/min) over a 14-day period, with no changes in normal treatment. The following indices were used to calculate PEF variability: 1) difference between morning PEF and nighttime PEF, expressed as a percentage of the mean value of the PEF measurements taken on that day; 2) minimum PEF rate during a week, expressed as a percentage of the highest value recorded during that week; 3) difference between the highest and the lowest PEF values, expressed as a percentage of the highest value; and 4) the 10th percentile of PEF values recorded during a week, expressed as a percentage of the highest value recorded during that week. We assessed agreement between clinical classification and PEF variability using the weighted kappa coefficient. We also analyzed the sensitivity and specificity of PEF variability indices for episodic and persistent asthma.

RESULTS

The analysis of levels of agreement between clinical classification of asthma and formulas 1, 2, 3, and 4 gave quadratic weighted kappa coefficients of 0.494, 0, 0.488, and 0.346, respectively. The results were similar when patients were grouped and analyzed by type of asthma (episodic or persistent asthma).

CONCLUSIONS

The monitoring of PEF variability, a recommendation common in national and international guidelines on the management of asthma in children, is not valid for classifying severity of asthma in children.

[Metered-dose inhaler with spacer vs nebulization for severe and potentially severe acute asthma treatment in the pediatric emergency department]

OBJECTIVE

To compare treatment with beta 2 agonist delivered either by a spacer device or a nebulizer in children with severe or potentially severe acute asthma.

METHODS

In this randomized trial, children 4 to 15 years, cared for in the emergency department for severe or potentially severe acute asthma, received 6 times either nebulizations of salbutamol (0.15mg/kg) or puffs of a beta 2 agonist (salbutamol 50 microg/kg or terbutaline 125 microg/kg). The primary outcome was the hospitalization rate. Secondary outcomes included percentage improvement in Bishop score, in PEF, SaO(2), respiratory and heart rates, side effects, length of stay and relapses 10 and 30 days later.

RESULTS

Groups did not differ for baseline data. There were no significant differences between the 2 groups (nebulizer N=40, spacer N=39) for baseline characteristics before emergency department consultation except for length of acute asthma in the spacer group. Clinical evolution after treatment, hospitalization rate, relapse were similar including the more severe subgroup. In the spacer group, tachycardia was less frequent (P<0.02). The overall length of stay in the emergency department was significantly shorter (148+/-20 vs 108+/-13 min, P<10(-9)).

CONCLUSIONS

The administration of beta 2 agonist using a metered-dose inhaler with spacer is an effective alternative to nebulizers for the treatment of children with severe or potentially severe acute asthma in the emergency department. Time gained can be used for asthma education.

Comparison of levalbuterol and racemic albuterol combined with ipratropium bromide in acute pediatric asthma: a randomized controlled trial

Our study compared levalbuterol (LEV) to the combination of racemic albuterol (RAC) and ipratropium bromide (IB) in 140 patients aged 6-18 years presenting to a tertiary hospital Emergency Department with acute asthma and a peak expired flow rate (PEF)<80% predicted. Patients were randomized to: LEV (<or=6 nebs LEV 1.25 mg); or RAC/IB (<or=3 nebs RAC 5.0 mg+IB 0.25 mg followed as needed by <or=3 nebs RAC 5.0 mg). No difference was noted in the study population (mean age 11.6 years and initial mean predicted PEF 49.5%) between LEV (n=72) and RAC/IB (n=68) for study outcomes except for measures of heart rate (HR). Median % HR increase for RAC/IB (26%) exceeded LEV (9%) (p<0.001). In a sample of children with acute asthma and initial mean PEF<50% predicted, LEV was associated with less tachycardia but had no other advantage over RAC combined with IB.

Evaluation of severity of bronchial asthma through an exercise bronchial challenge

Optimum treatment of bronchial asthma requires accurate diagnosis and severity classification. We studied the use of an exercise bronchial challenge in the asthmatic patient as a diagnostic tool. An exercise bronchial challenge test was carried out in 431 asthmatic children and 114 children without a history of asthma in a moderate-altitude environment (2,230 m above sea level/7,314 feet above sea level). Values of peak expiratory flow (baseline and maximum fall) were analyzed through time in each asthma severity group (intermittent, mild persistent, moderate persistent, severe persistent, and nonasthmatic controls). There was a significant difference among responses of asthma severity groups for almost all variables. No difference was found between nonasthmatic and intermittent groups who had similar behavior, except in bronchodilator response. An exercise bronchial challenge helps classify a patient according to asthma severity; it is easy to reproduce and does not require expensive equipment. It allows diagnosing and classifying asthma severity easily and supplementing the clinical evaluation. Based on our results, we propose a fall of PEF >or= 11% as new cutoff point for making a diagnosis of persistent bronchial asthma. A fall of 11-25% indicates mild persistent asthma; from 25-50%, moderate persistent asthma; and a bigger fall, severe persistent asthma.

Induced sputum in children with newly diagnosed mild asthma: the effect of 6 months of treatment with budesonide or disodium cromoglycate

BACKGROUND

There are few controlled studies on the effects of anti-inflammatory treatment on airway inflammation in newly diagnosed childhood asthma.

METHODS

Sixty children with newly diagnosed mild persistent asthma, 5-10 years of age, and 17 healthy control subjects were studied. Asthmatic children were randomized into an open study with two treatment groups: (1) budesonide 400 microg twice daily for 1 month, 200 microg twice daily for 5 months and (2) disodium cromoglycate (DSCG) 10 mg three-times daily for 6 months. All exacerbations were treated with budesonide 400 microg twice daily for 2 weeks. Symptoms and lung function were recorded throughout the study.

RESULTS

Sputum induction was safe and the overall success rate was 71%. This improved with age and decreased after treatment. At baseline, the asthmatic children had more eosinophils in blood (0.26 vs 0.18 x 10(9)/l, P = 0.03) and sputum (1.1 vs 0.0 %, P = 0.0001) than the control subjects. The numbers of sputum eosinophils correlated with bronchial responsiveness (R = -0.58, P = 0.0002). Eosinophils were higher in children with atopic asthma than with nonatopic asthma (P < 0.0001), and in children with a history wheezing than in children without wheezing (P = 0.02). Six months of budesonide treatment, but not of DSCG, improved lung function (P = 0.007), decreased symptoms (P = 0.007) and sputum eosinophils (P = 0.003). The effects of budesonide were pronounced in children with intense sputum eosinophilia (>3%).

CONCLUSION

Sputum eosinophilia is present in children with newly diagnosed mild persistent asthma. Treatment with inhaled budesonide, but not with DSCG, decreases sputum eosinophils along with clinical and functional improvement.