Persisting airway obstruction in asymptomatic children with asthma with normal peak expiratory flow rates

Characterization of exhaled breath condensate (EBC) non-exchangeable hydrogen functional types and lung function of wildland firefighters

Inhalation of smoke is shown to be associated with adverse respiratory outcomes in firefighters. Due to invasiveness of procedures to obtain airways lining fluid, the immediate responses of the target organ (i.e. lung) are secondarily assessed through biomarkers in blood and urine. The objective of this study was to identify changes in metabolic profile of exhaled breath condensate (EBC) and lung function of firefighters exposed to wildfires smoke. A total of 29 subjects were studied over 16 events; 14 of these subjects provided cross-shift EBC samples. The predominant types of non-exchangeable hydrogen in EBC were saturated oxygenated hydrogen, aliphatic alkyl and allylic. Non-exchangeable allylic and oxygenated hydrogen concentrations decreased in post-exposure EBC samples. Longer exposures were correlated with increased abundance of oxidized carbon in ketones, acids and esters. Post-exposure lung function declines (forced expiratory volume in 1 s (FEV₁): 0.08 l, forced vital capacity (FVC): 0.07 l, FEV₁/FVC: 0.03 l, peak expiratory flow (PEF): 0.39 l s^-1) indicated airways inflammation. They were related to exposure intensity (FEV₁ and FVC) and exposure duration (PEF). This study showed that EBC characterization of non-exchangeable hydrogen types by NMR may provide insights on EBC molecular compositions in response to smoke inhalation and facilitate targeted analysis to identify specific biomarkers.

Determinants of Allergic Sensitization, Asthma and Lung Function: Results from a Cross-Sectional Study in Italian Schoolchildren

Prenatal smoking exposure and early-life respiratory infections are major determinants of asthma during childhood. We investigate the factors influencing allergic sensitization (AS), asthma, and lung function in children and the balance between individual and environmental characteristics at different life stages. 1714 children aged 7–16 years and living in southern Italy were investigated using a parental questionnaire, skin prick tests, and spirometry. We found 41.0% AS prevalence: among children without parental history of asthma, male sex, maternal smoking during pregnancy (MatSmoke), and acute respiratory diseases in the first two years of life (ARD2Y) were significant risk factors for AS. MatSmoke was associated (OR = 1.79) with ARD2Y, and this association was influenced by sex. ARD2Y was, in turn, a significant risk factor (OR = 8.53) for childhood current asthma, along with AS (OR up to 3.03) and rhinoconjuctivitis (OR = 3.59). Forced mid-expiratory flow (FEF_25–75%) was negatively affected by ARD2Y, with a sex-related effect. Thus, males exposed to MatSmoke had significantly lower FEF_25–75% than unexposed males. Despite the difficulty of discriminating among the complex interactions underlying the development of allergic respiratory diseases, ARD2Y appears to strongly influence both asthma and lung function during childhood. In turn, ARD2Y is influenced by prenatal exposure to tobacco smoke with a sex-dependent effect.

Recognition of the peripheral airway impairment phenotype in children with well-controlled asthma

BACKGROUND

Peripheral airway impairment, although frequently unrecognized, is a risk factor for poor asthma control, loss of control, increased exacerbations, airway hyperresponsiveness, and loss of lung function with age, even in patients with well-controlled asthma.

OBJECTIVE

To determine the presence of peripheral airway impairment by impulse oscillometry and forced expiratory flow between 25% and 75% (FEF_25%-75%) in children whose asthma is well controlled by National Asthma Education and Prevention Program (NAEPP) guidelines.

METHODS

In this retrospective, cross-sectional analysis, outcomes were evaluated across 192 encounters in 139 patients with moderate to severe asthma, ages 4-18 years. Receiver operator characteristic curves were created and oscillometry thresholds determined by maximizing the sum of sensitivity and specificity to identify those whose condition is not well controlled. Impairment was then identified for those whose condition was well controlled when these age-dependent oscillometry thresholds were met for each IOS measure or FEF_25%-75% < 65% of predicted.

RESULTS

Reactance at 5 Hz (X5) appeared most robust to identify peripheral airway impairment. In 96 well-controlled asthma encounters, impairment was identified by X5 in approximately 20% and 45% for those younger than 12 years and adolescents, respectively, compared with a maximum of 10% with FEF_25%-75% in the adolescent cohort (P < .05).

CONCLUSION

We conclude that peripheral airway impairment, determined by oscillometry, is common in patients with well-controlled asthma across age cohorts. X5 with optimal cut points ≤ -3.8, ≤ -2.5, and ≤ -1.5 cmH₂O/L/s for ages 4-7, 8-11, and >12 years, provides the clinician with a practical tool to identify the presence of the peripheral airway impairment phenotype that is consistently superior to FEF_25%-75%. This recognition, if confirmed, may reduce the risk of asthma-associated consequences with earlier and more targeted therapy.

Role of FEF25–75 as an Early Marker of Bronchial Impairment in Patients with Seasonal Allergic Rhinitis

Background

Allergic rhinitis may be associated with asthma. Forced expiratory flow between 25 and 75% of vital capacity (FEF25–75) is a measure of small airways narrowing. The aim of this study was to evaluate whether patients with seasonal allergic rhinitis (SAR) without symptoms of asthma might, nevertheless, have airways obstruction both in and out of the pollen season.

Methods

Fifty patients (mean age, 23.7 ± 4.9 years) with SAR were evaluated both during and outside the pollen season. All of them had moderate–severe grade of nasal obstruction. Total symptom score, rhinomanometry, nasal lavage, nasal scraping, spirometry, and methacholine (MCH) bronchial challenge were assessed in all subjects.

Results

Although data on forced vital capacity and response to MCH were similar in and out of the pollen season, all other parameters were markedly different. The major finding of the study was that FEF25–75 was significantly associated with nearly all of the parameters considered, including bronchial hyperreactivity, with Pearson R ranging from 31 to 75% and differences in mean FEF25–75 ranging between 14.5 and 16.5% of predicted. The more significant association was with nasal airflow in the pollen season (R = 82.8%; p < 0.001). A significant association persisted for all parameters while controlling for season.

Conclusion

This study highlights the link between upper and lower airways and the role of FEF25–75 as an early marker of bronchial impairment in those patients with SAR alone.

[Application of pulmonary function and fractional exhaled nitric oxide tests in the standardized management of bronchial asthma in children]

OBJECTIVE

To investigate the changes of pulmonary function and fractional exhaled nitric oxide (FeNO) in the standardized treatment of bronchial asthma in children.

METHODS

A total of 254 children who were newly diagnosed with acute exacerbation of bronchial asthma were selected as asthma group, and they were divided into two subgroups: asthma with concurrent rhinitis and asthma without concurrent rhinitis. All patients received the standardized management and treatment for one year. The pulmonary function parameters included forced expiratory volume in one second (FEV1), peak expiratory flow (PEF), maximal mid-expiratory flow (MMEF), and mid-expiratory flow at 25%, 50%, and 75% of vital capacity (MEF25, MEF50, and MEF75). The FeNO levels were measured before treatment and at 3, 6, 9, and 12 months after treatment. Another 62 healthy children were selected as the control group, and the pulmonary function and FeNO levels were measured only once.

RESULTS

During one year of standardized treatment, FEV1, PEF, MMEF, MEF25, MEF50, and MEF75 gradually increased, and FeNO levels gradually decreased (P<0.05). Indicators of large airway function, such as FEV1 and PEF, almost returned to normal after 6 months of treatment; indicators of small airway function, such as MMEF, MEF25, MEF50, and MEF75 almost returned to normal after 9 months of treatment; there were no significant differences in the above indices between the asthma group and the control group after one year of treatment (P>0.05). However, the asthma group had a significantly higher FeNO levels than the control group after one year of treatment (P<0.05). The asthmatic patients with concurrent rhinitis had significantly higher FeNO levels than those without concurrent rhinitis before treatment and 3 months after treatment (P<0.05). Before treatment, there was a significant negative correlation between FeNO levels and pulmonary function parameters (P<0.05).

CONCLUSIONS

With the standardized treatment of bronchial asthma in children, pulmonary function parameters gradually increase and FeNO levels gradually decrease. The recovery of large airway function occurs earlier than the recovery of small airway function. Furthermore, the effect of rhinitis on airway responsiveness should be noted.

Single breath counting for the evaluation of pediatric respiratory function: derivation of a "normogram"

Single breath counting (SBC) is the measurement of how far an individual can count in cadence with a metronome set at 2 beats per second in a normal speaking voice following a maximal effort inhalation. Previous work has demonstrated that it correlates well with standard measures of pulmonary function. The objective of this study is to derive a "normogram" of healthy children showing the expected SBC value as a function of easily measured physiologic parameters (age, gender, height, and weight). This was a prospective observational study of a convenience sample of healthy children presenting for well-child checks or non-respiratory complaints at a large tertiary care center. Correlation was determined by the Pearson's product correlation coefficient (r) and r (2) determined as a measure of shared variance. Multiple regression analysis was performed on demographic data to determine a best linear fit with calculation of the coefficient of determination (R (2)). A total of 105 children served as the basis for analysis; 54 (51.4 %) were male and average age was 9.7 (median 10, range 3-15) years. For both males and females, height correlated most strongly with SBC score (r = 0.730 and 0.725, respectively). In both genders, height alone accounted for more than 50 % of the observed variance in the results (r (2) = 0.533 and 0.526, respectively). Breath counting, an easy to perform test that appears to correlate well with standard measures of pulmonary function and shows promise for measuring asthma severity in children. We present an equation for predicting normal results (a "normogram").

Sensitivity of different spirometric tests for detecting airway obstruction in childhood asthma

OBJECTIVE

The objective of this study was to compare different measures of airflow obstruction by spirometry in childhood asthma. The objectives were; (a) to compare sensitivity of large airway tests (FEV1 and PEFR) with tests at low lung volumes (small airways) (FEF25-75, FEF50 and FEF75); (b) compare within each group which individual tests are more sensitive.

METHODS

This was a retrospective analysis of 2307 spirometry tests performed during outpatient visits on 821 doctor-diagnosed asthma patients aged 6-18. Tests were deemed acceptable if they were acceptable and repeatable by American Thoracic Society (ATS) criteria.

RESULTS

In mild obstruction, FEV1 detected 6.8% abnormal tests while FEF75 detected 33% (p < 0.0001). In more severe obstruction, the difference was more obvious (FEV1 14.8%; FEF75 71%). Tests at low lung volumes (small airway tests) were also more sensitive than PEFR. Within groups, FEV1 was more sensitive than PEFR in the large airway tests and FEF75 was more sensitive than FEF25-75 and FEF50 among the tests at low lung volumes (small airway tests). The FEV1/FVC ratio correlated more closely with tests at low lung volumes (small airway tests), than with large airway tests.

CONCLUSIONS

(1) Tests at low lung volumes (small airway tests) are more sensitive than large airway tests; (2) Within groups, the FEV1 is better than PEFR and FEF75 is better than FEF25-75 or FEF50.

The impact of intranasal corticosteroids on lung function in children with allergic rhinitis

BACKGROUND

Subjects with allergic rhinitis (AR) suffer from impaired lung function, especially decreased FEF(25-75%). The purpose of this study was to examine lung function and the long-term response to INCS in AR patients with impaired lung function, and to characterize the phenotype of these children.

METHODS

Two hundred two children with AR underwent an allergy evaluation including a skin prick test and spirometry. Children with impaired lung function were treated with daily nasal corticosteroids spray (INCS) and antihistamine as needed.

RESULTS

Fifty-three children out of 202 (26.3%) had impaired lung function: 34 of them (64.2%) had FEF(25-75%) values under 80% of predicted and normal FEV(1) values, and 19 individuals (35.8%), had both FEF(25-75%) and FEV(1) values below 80% of predicted. A positive correlation between FEV(1) and FEF(25-75%) values (r = 0.369, P = 0.007) and a reverse correlation between duration of nasal symptoms and FEF(25-75%) values (r = -0.364, P = 0.012) were found. Post-ronchodilation FEV(1) levels increased from 81.9 ± 8.0 to 87.7 ± 10.4 (P < 0.0001). Thirty-five of the 53 children complied with a continuous INCS treatment regimen over a period of 3-12 months, demonstrated increased FEF(25-75%) (84.4 ± 13.6 vs. 70.1 ± 7.1, P < 0.001) and FEV(1) (92.3 ± 10.9 vs. 84.4 ± 7.8, P < 0.0001) after INCS treatment. However, FEF(25-75%) values were still significantly lower compared to the group of AR children with normal lung function (84.4 ± 13.6 vs. 95.7 ± 8.8, P < 0.0001).

CONCLUSIONS

INCS improve FEF(25-75%) above 80% of predicted values in 2/3 of children with abnormal lung function. However, this improvement does not reach levels of AR children with normal lung function. Pediatr

Fractional exhaled nitric oxide and forced expiratory flow between 25% and 75% of vital capacity in children with controlled asthma

Purpose

Fractional exhaled nitric oxide (FeNO) and forced expiratory flow between 25% and 75% of vital capacity (FEF_25-75) are not included in routine monitoring of asthma control. We observed changes in FeNO level and FEF_25-75 after FeNO-based treatment with inhaled corticosteroid (ICS) in children with controlled asthma (CA).

Methods

We recruited 148 children with asthma (age, 8 to 16 years) who had maintained asthma control and normal forced expiratory volume in the first second (FEV₁) without control medication for ≥3 months. Patients with FeNO levels >25 ppb were allocated to the ICS-treated (FeNO-based management) or untreated group (guideline-based management). Changes in spirometric values and FeNO levels from baseline were evaluated after 6 weeks.

Results

Ninety-three patients had FeNO levels >25 ppb. These patients had lower FEF_25-75% predicted values than those with FeNO levels ≤25 ppb (P<0.01). After 6 weeks, the geometric mean (GM) FeNO level in the ICS-treated group was 45% lower than the baseline value, and the mean percent increase in FEF_25-75 was 18.% which was greater than that in other spirometric values. There was a negative correlation between percent changes in FEF_25-75 and FeNO (r=-0.368, P=0.001). In contrast, the GM FeNO and spirometric values were not significantly different from the baseline values in the untreated group.

Conclusion

The anti-inflammatory treatment simultaneously improved the FeNO levels and FEF_25-75 in CA patients when their FeNO levels were >25 ppb.

The utility of forced expiratory flow between 25% and 75% of vital capacity in predicting childhood asthma morbidity and severity

OBJECTIVES

The forced expiratory volume in 1 second (FEV(1)) felt to be an objective measure of airway obstruction is often normal in asthmatic children. The forced expiratory flow between 25% and 75% of vital capacity (FEF(25-75)) reflects small airway patency and has been found to be reduced in children with asthma. The aim of this study was to determine whether FEF(25-75) is associated with increased childhood asthma severity and morbidity in the setting of a normal FEV(1), and to determine whether bronchodilator responsiveness (BDR) as defined by FEF(25-75) identifies more childhood asthmatics than does BDR defined by FEV(1).

METHODS

The Boston Children's Hospital Pulmonary Function Test database was queried and the most recent spirometry result was retrieved for 744 children diagnosed with asthma between 10 and 18 years of age between October 2000 and October 2010. Electronic medical records in the 1 year prior and the 1 year following the date of spirometry were examined for asthma severity (mild, moderate, or severe) and morbidity outcomes for the three age, race, and gender-matched subgroups: Group A (n = 35) had a normal FEV(1), FEV(1)/forced vital capacity (FVC), and FEF(25-75); Group B (n = 36) had solely a diminished FEV(1)/FVC; and Group C (n = 37) had a normal FEV(1), low FEV(1)/FVC, and low FEF(25-75). Morbidity outcomes analyzed included the presence of hospitalization, emergency department visit, intensive care unit admission, asthma exacerbation, and systemic steroid use.

RESULTS

Subjects with a low FEF(25-75) (Group C) had nearly 3 times the odds ratio (OR) (OR = 2.8, p < .01) of systemic corticosteroid use and 6 times the OR of asthma exacerbations (OR = 6.3, p > .01) compared with those who had normal spirometry (Group A). Using FEF(25-75) to define BDR identified 53% more subjects with asthma than did using a definition based on FEV(1).

CONCLUSIONS

A low FEF(25-75) in the setting of a normal FEV(1) is associated with increased asthma severity, systemic steroid use, and asthma exacerbations in children. In addition, using the percent change in FEF(25-75) from baseline may be helpful in identifying BDR in asthmatic children with a normal FEV(1).

FEF(25-75) might be a predictive factor for bronchial inflammation and bronchial hyperreactivity in adolescents with allergic rhinitis

Allergic rhinitis and asthma are closely associated. Bronchial hyperreactivity (BHR) is a pathophysiological characteristic of asthma. Allergic inflammation is characterized by eosinophilic infiltrate and may by indirectly assessed by exhaled nitric oxide (FeNO). Forced expiratory flow between 25 percent and 75 percent of vital capacity (FEF25-75) may predict BHR in adult patients with allergic rhinitis. The aim of this study was to evaluate the presence of BHR in a large group of adolescents with allergic rhinitis and whether FEF25-75 might be related with BHR and FeNO. Methods 150 adolescents with allergic rhinitis were enrolled. Clinical examination, skin prick test, spirometry, methacholine challenge, and FeNO were performed in all patients. Results Severe BHR is quite frequent in allergic adolescents. Impaired FEF25-75 values (such as less than 65 percent of predicted) constitute a relevant predictive factor for severe BHR (OR 4.4). FeNO levels were significantly related with BHR. Conclusion This study provides evidence that impaired FEF25-75 values might predict severe BHR and BHR is related with FeNO in adolescents. Therefore, BHR should be suspected in adolescents with low FEF25-75 values.

Phenotypic differences between asymptomatic airway hyperresponsiveness and remission of asthma

BACKGROUND

The present study aimed to illustrate differences in characteristics and perception of dyspnea between young atopic adults who have no history of asthma (never-asthmatics) with or without asymptomatic airway hyperresponsiveness (AHR) and those who had childhood asthma and consider themselves to be grown out of the disease (past-asthmatics).

METHODS

Blood parameters, lung function and methacholine PC(20) were measured in 88 never-asthmatics and 24 past-asthmatics. A perception score of dyspnea at 20% fall in FEV(1) (PS(20)) was obtained by interpolation of the two last points on the perception (modified Borg scale)/fall in FEV(1) curve during methacholine challenge.

RESULTS

Thirty-one of 88 never-asthmatics and eighteen of 24 past-asthmatics exhibited AHR (PC(20) was <8 mg/ml). Higher levels of specific IgE to house dust mite in past-asthmatics were observed than never-asthmatics with and without AHR. Mean values of FEV(1) and FEF(25-75) (%predicted) were significantly lower in past-asthmatics than never-asthmatics without AHR, and the values in never-asthmatics with AHR were intermediate between never-asthmatics without AHR and past-asthmatics. PC(20) was not significantly different between past-asthmatics and never-asthmatics with AHR. Of particular interest was that PS(20) was significantly lower in never-asthmatics with AHR compared with past-asthmatics.

CONCLUSION

The present findings suggest the possibilities that presence or absence of past history of outgrow of childhood asthma might be associated with airway narrowing, sensitization to house dust mite and perception of dyspnea in young asymptomatic adults with atopy and AHR.

Effects of ambient air pollution on lung function growth in Chinese schoolchildren

OBJECTIVE

To evaluate the adverse effect of exposure to air pollution on lung function growth in school-aged children.

METHODS

A cohort of 1983 children from three districts in Guangzhou, China was followed-up for 6 months. The children performed pulmonary function tests twice, and their parents reported the child's respiratory symptoms by self-administered questionnaires in both surveys.

RESULTS

The annual mean concentrations of air pollutants for the past 5 years for particulate matter less than 10 microns in diameter (PM(10)), nitrogen (NO(2)), and sulfur dioxide (SO(2)) were respectively: 96.1 microg/m(3), 76.0 microg/m(3), and 65.7 microg/m(3) in the highly-polluted district (HPD), 80.3 microg/m(3), 67.6 mug/m(3), and 54.5 microg/m(3) in the moderately-polluted district (MPD), and 80.0 microg/m(3), 48.1 microg/m(3), and 52.2 microg/m(3) in the least-polluted district (LPD). After adjustment for potential confounders, significant deficits were found in the annual growth rates of forced expiratory flows at 25% (FEF(25)), and between 25% and 75% (FEF(25-75)) in boys and FEF(25) in girls (In boys, for FEF(25), -0.136 l/s, p = 0.008 in MPD and -0.153 l/s, p = 0.004 in HPD, respectively; for FEF(25-75), -0.176 l/s, p = 0.013 in MPD and -0.167 l/s, p = 0.021 in HPD, respectively. In girls, for FEF(25), -0.123 l/s, p = 0.043 in HPD), using LPD as the reference. Deficits in the annual growth rate of forced expiratory volume in 1 s (FEV(1)) were also negatively associated with air pollution in boys (-0.063 L, p = 0.032 in HPD).

CONCLUSIONS

The study adds more evidence that exposure to air pollution has adverse effects on lung function growth in schoolchildren.

Single-breath counting: a pilot study of a novel technique for measuring pulmonary function in children

INTRODUCTION

Although peak expiratory flow rate is the conventional way to measure asthma severity in adults, its use is problematic in children because it is effort dependent. Forced expiratory volume in 1 second (FEV₁) and the ratio of FEV₁ to forced vital capacity (FEV₁/FVC) are more accurate, but generally not available in the emergency department (ED). A better test is needed. Single-breath counting (SBC) is the measurement of how far an individual can count in a normal speaking voice after a maximal effort inhalation. The count is in cadence to a metronome set at 2 beats per second. Previous work has suggested that SBC correlates with standard measures of pulmonary function in adults. However, it has never been tested in children.

OBJECTIVES

The aims of this study are to determine if SBC can be easily performed by children and to assess the correlation between SBC and standard measures of pulmonary function in a pediatric population.

METHODS

This was a prospective observational study of a convenience sample of children presenting to the pulmonary clinic for scheduled pulmonary function testing (PFT). Peak expiratory flow rate, FEV₁, FVC, forced expiratory flow 25% to 75%, and FEV₁/FVC were measured and recorded. After PFT, subjects were asked to perform SBC. Three attempts were allowed, and the average was recorded. Correlation was determined by the Pearson coefficient.

RESULTS

Sixty-seven children (ages 5-18 years, 64% male) were enrolled. All were able to understand and complete the testing. Indications for PFT included asthma and/or allergies (n = 44), cystic fibrosis (n = 9), and other chronic diseases (n = 14). The correlations (r) of SBC to peak expiratory flow rate, FEV₁, FVC, forced expiratory flow 25% to 75%, and FEV₁/FVC were 0.55, 0.66, 0.71, 0.44, and -0.29, respectively (P < .05 for all results).

CONCLUSION

Single-breath counting is easy to perform in children, seems to correlate well with standard measures of pulmonary function, and shows promise for measuring asthma severity in children. Further work to define the range of reference SBC values (as a function of age and/or body size) and an evaluation of the utility of SBC in an ED population of acute asthmatics is indicated.

Asthma control test and peak expiratory flow rate: independent pediatric asthma management tools

BACKGROUND

Management of asthma reflects the complexity of the pathogenesis. According to current National Heart Lung Blood Institute (NHLBI) guidelines, asthma control can be assessed using the validated asthma control test, measures of airway function, and overall assessment of risk and quality of life. We hypothesized that the asthma control test and measures of airway function are independent tools in asthma management. We also studied whether the presence of nasal symptoms is correlated to these measures.

METHODS

Serial visits (n = 45) to a pediatric respiratory clinic in an underserved area of San Diego County with a predominantly Hispanic population were reviewed. Patients were included if they were able to perform airway function tests and had more than one provider visit. Patients with other major diseases were excluded. We determined whether uncontrolled asthmatics, defined as an Asthma Control test (ACT) score of 19 or less, had lower % predicted peak expiratory flow Measurements as a group compared to those with higher scores. In addition, the individual ACT and airway function results were analyzed. Patients with and without nasal symptoms at the time of presentation were sub-analyzed to determine differences in ACT and peak flow measurements.

RESULTS

Based on n = 45 physician visits, the mean ACT score was 21 +/- 3.3 (range 12-25) and the mean peak expiratory flow rate (PEFR) was 87.4% +/- 11 (range 65-109%). Patients with ACT scores < or = to 19 or lower (< or = 90%) PEFRs were determined not to have more nasal symptoms. The measures of ACT and peak expiratory flow were independent and not correlated.

CONCLUSIONS

Our study indicates that ACT and PEFR are distinct parameters used to manage patients in a pediatric outreach asthma clinic.

Clinical implications of serum retinol-binding protein 4 in asthmatic children

Recently the prevalence of both asthma and obesity have increased substantially in many countries. The aim of this study was to evaluate the role of retinol-binding protein (RBP) 4 in childhood asthma and its association with atopy markers, pulmonary function, and bronchial hyperresponsiveness in relation to obesity. We studied 160 children between the ages 6 to 10 yr, including 122 asthmatics and 38 controls. The body mass index, pulmonary function tests, and methacholine challenge tests were measured on the same day. Total eosinophil count, serum total IgE, serum eosinophil cationic protein, and serum RBP4 were measured in all subjects. There was no difference in serum RBP4 levels between the asthmatics and the control group. In all subjects or subgroups, serum RBP4 was not associated with total eosinophil count, serum total IgE, serum eosinophil cationic protein, or PC(20). There was no relationship between serum RBP4 and pulmonary function in female asthmatics. Forced expiratory volume in 1 second/forced vital capacity (FVC) and forced expiratory flow between 25% and 75% of FVC contributed to serum RBP4 in male asthmatics. Our findings show an association between RBP4 and pulmonary function in prepubertal male asthmatics. This relationship may indirectly affect the high prevalence of childhood asthma in males.

High-pitched breath sounds indicate airflow limitation in asymptomatic asthmatic children

BACKGROUND AND OBJECTIVE

Asthmatic children may have airway dysfunction even when asymptomatic, indicating that their long-term treatment is less than optimal. Although airway dysfunction can be identified on lung function testing, performing these tests can be difficult in infants. We studied whether breath sounds reflect subtle airway dysfunction in asthmatic children.

METHODS

The highest frequency of inspiratory breaths sounds (HFI) and the highest frequency of expiratory breath sounds (HFE) were measured in 131 asthmatic children while asymptomatic and with no wheezes for more than 2 weeks. No child was being treated with inhaled corticosteroids (ICS). Breath sounds were recorded and analysed by sound spectrography and compared with spirometric parameters. After initial evaluation, cases with more than step 2 (mild persistent) asthma were treated using inhaled fluticasone (100-200 microg/day) for 1 month, and then breath sound analysis and pulmonary function testing were repeated.

RESULTS

On initial evaluation, HFI correlated with the percentage of predicted FEF(50) (%FEF(50)), (r = -0.45, P < 0.001), the percentage of predicted FEF(75) (%FEF(75)) (r = -0.456, P < 0.001), and FEV(1) as a percentage of FVC (FEV(1)/FVC (%)) (r = -0.32, P < 0.001). HFI did not correlate with the percentage of predicted PEF (%PEF). The 69 children with lower than normal %FEF(50) were then treated with ICS. The %FEF(50) and %FEF(75) improved after ICS treatment, and increases in %FEF(50) (P < 0.005) correlated with decreases in HFI (P < 0.001).

CONCLUSIONS

Higher HFI in asymptomatic asthmatic children may indicate small airway obstruction. Additional ICS treatment may improve the pulmonary function indices representing small airway function with simultaneous HFI decreases in such patients.

[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.

Not all children with under-control asthma are controlled

Subclinical lung function alterations can sometimes be discovered in asthmatic patients under clinical control. This study aimed to identify the burden of asthmatic children with subclinical airways abnormalities who may benefit from an adjustment in asthma therapy. 134 6-to-17-year-old asthmatic children were enrolled. Of them, 98 presented apparently under clinical control disease and all performed spirometry before and after bronchodilation: 17 (17.3%) had a positive bronchodilation test, in addition to significantly lower lung function indexes as compared to those with under-control asthma who had a negative bronchodilation test. These patients were randomized and re-evaluated: patients (n=8) receiving an adjustment in their therapy showed an improvement in lung function tests and quality of life indexes as compared to 7 without therapy adjustment. In conclusion, a substantial number of apparently-under-control asthmatic children show airways alterations that can be improved by adjusting their therapy, which also seems to enhance their quality of life.

Peak expiratory flow variability adjusted by forced expiratory volume in one second is a good index for airway responsiveness in asthmatics

BACKGROUND

The lowest peak expiratory flow (PEF) over a week, expressed as a percentage of the highest PEF (Min%Max PEF) has been reported to be the index that most closely correlates with airway hyperresponsiveness (AHR) in asthmatics. However, both fluctuation of the airway caliber and airflow limitation are regarded as physiological properties of asthma closely related to AHR. An accurate index that shows the degree of AHR may be obtained by combining the index of airway lability with the parameters that represent airway caliber.

METHODS

Ninety-two steroid-naive and twenty-eight steroid-treated asthmatic patients were enrolled. Using the physiological parameters obtained from spirometry and PEF monitoring, we investigated the indices which correlate accurately with airway responsiveness measured by the inhalation challenge test.

RESULTS

Although the methacholine threshold was related to all parameters that represent airway caliber and lability, Min%Max PEF had the strongest correlation with AHR. When Min%Max PEF was adjusted by the airway geometric factors, the normalization of Min%Max PEF with forced expiratory volume in one second as a percentage of the predicted value (%FEV(1)) improved the relationship between Min%Max PEF and AHR.

CONCLUSIONS

Min%Max PEF adjusted by %FEV(1) showed a good correlation with airway responsiveness measured by the inhalation challenge test, and may be useful as a convenient alternative index of AHR in asthmatic patients.

Parent-reported symptoms may not be adequate to define asthma control in children

INTRODUCTION

Asthma guidelines have suggested that treatment decisions should be guided by indices of asthma control and not only by disease severity. In adults, symptom-based asthma control parameters have been shown to predict exacerbations and health care services use (HSU). We hypothesize that defining asthma control using parent-reported symptoms alone is not adequate in children.

MATERIALS AND METHODS

Cross-sectional data from the population-based asthma in Canada study were reanalyzed. Random-digit dialing was used to produce the final sample, consisting of 1,001 asthmatics: 801 adults (aged 16+) and 200 children (aged 4-15) participating by parental proxy. Weighted frequencies of Canadian guideline defined asthma control parameters, perceived asthma control, HSU and medication use were calculated separately for adults and children. Stratified analyses compared HSU in controlled versus uncontrolled asthmatics.

RESULTS

Over 90% of parents of asthmatic children believed their child's asthma to be controlled. Only 45% were actually controlled as defined by guideline parameters. Among controlled asthmatics, children reported higher HSU (32% reported 2+ health care encounters versus 17% of adults, P < 0.001). Irrespective of control and despite similar use of controller therapy, children reported a higher number of health care encounters than adults (any emergency department visits 37% vs. 24%, P = 0.00003; unscheduled doctor visits 59% vs. 36%, P < 0.00001). While reporting higher HSU, asthmatic children had less frequent episodes of excessive daytime symptoms than adults (29% vs. 49%, respectively, P < 0.0001).

DISCUSSION

Current symptom-based asthma control parameters reported by parental proxy are likely poor predictors of asthma HSU and may not provide adequate asthma control estimates in children.

Home monitoring in asthma self-management

Peak flow monitoring of asthma came into vogue with the advent of asthma self-management programs. Because it offered an objective way to gauge asthma severity, it promised improvement in the accuracy of asthma monitoring over that attainable by symptom monitoring. This promise has not been fulfilled. The ensuing years have witnessed a debate concerning the relative merits of symptom and peak flow monitoring. The debate has focused both on the degree to which peak flow and symptom scores are related to one another and on the relative effectiveness of symptom and peak flow monitoring for asthma control. We review research relating to these topics. The work shows that the strength of the relationship between peak flow and symptoms is low to moderate and varies between individuals and that benefits of peak flow monitoring in asthma self-management provide, at best, no more than a small increment in effectiveness beyond that afforded by symptom monitoring.

A randomized, double-blind trial of the effect of anti-asthma treatment on lung function in children with asthma

BACKGROUND

Pulmonary function tests (PFTs) and especially spirometry measures are useful tools in evaluating early response to treatment of asthma in children mainly due to their worldwide availability. The aim of our study was to determine the effects of anti-asthma treatment in children, equally on FEV(1), FEF25-75%, R(int) and SR(aw) values.

METHODS

Children 6-18 years of age with moderate atopic asthma were randomized to 4-week, placebo-controlled, double-blind trial. Patients were randomly allocated to receive 200 microg budesonide (B) (n=29), 5 or 10 mg (according to age) montelukast (M) (n=29), 200 microg B + 5 or 10 mg M (n=29), 200 microg B + 9 microg formoterol (F) (n=29) or placebo (n=27). FEV(1,) FEF25-75%, R(int), SR(aw) were measured before and after treatment.

RESULTS

R(int), SR(aw), FEV(1) improved significantly in all active treatment groups while FEF25-75% improved significantly only in BM group and M group. Combination therapy, showed significantly greater effects on R(int) than monotherapy: BM group compared to B group (P=0.01) and M group (P=0.03) and BF group compared to B group (P=0.01) and M group (P=0.04).

CONCLUSION

This study shows that using single parameter for monitoring asthma can be misleading. Using combination of lung function techniques provides better assessment of treatment. Results of our study confirm this hypothesis. The best effect on large and small airways was achieved with combined anti-inflammatory therapy.

Role of FEF25%–75% as a predictor of bronchial hyperreactivity in allergic patients

BACKGROUND

The small airways may play an important role in the clinical manifestations of asthma. Forced expiratory flow between 25% and 75% (FEF25%-75%) has been proposed as an approximate measure of the caliber of distal airways. Bronchial hyperreactivity (BHR) is a feature of asthma.

OBJECTIVE

To evaluate the possible role of FEF25%-75% as a predictor of BHR in allergic patients with asthma and rhinitis.

METHODS

A total of 726 patients (mean +/- SD age, 24.7 +/- 6.3 years) were evaluated. Spirometry and methacholine bronchial challenge were evaluated in all the participants.

RESULTS

A difference between forced expiratory volume in 1 second and FEF25%-75% greater than 20 or a ratio between these variables greater than 1.24 discriminates between patients with no response to a mild response to methacholine vs patients with a moderate-to-severe response with high sensitivity (P < .001).

CONCLUSION

This study highlights the possible role of FEF25%-75% in predicting BHR in allergic individuals with airway disorders.

Relationship between lung function and asthma symptoms in patients with difficult to control asthma

Several studies have demonstrated a poor relationship between measures of asthma control and lung function in patients with asthma. We sought to examine this relationship in a cohort of difficult to control asthmatics attending a hospital outpatient clinic. FEV1 % and asthma control scores (ACSs) were measured at the first clinic visit and at a follow-up visit. A total of 59 patients took part in the study. At the initial visit, FEV1 % correlated with limitation of activity (p = 0.002), shortness of breath (p = 0.02), wheezing (p = 0.029), and ACS (p = 0.014). However, at follow-up, there was no correlation between FEV1 % and any measured index of asthma control. When patients with severe fixed airflow obstruction were excluded from the analysis (n = 16), FEV1 % at follow-up became significantly correlated with night waking (p = 0.02), wheezing (p = 0.05), and ACS (p = 0.036). The improvement in asthma control score at follow-up was significantly and strongly associated (r = 0.51 for total asthma control, p < 0.001) with the improvement in lung function in patients without severe fixed airflow obstruction. Lung function was not associated with any measure of asthma control in patients with severe fixed airflow obstruction. FEV1 % correlates well with asthma symptoms in difficult asthma patients with poor control but not when control improves. This loss of relationship is due to subjects with severe fixed airflow obstruction where good subjective control does not exclude the presence of significant obstruction. How severe fixed airflow obstruction should be prevented, delayed, or managed in asthma requires further research.

Montelukast administered in the morning or evening to prevent exercise-induced bronchoconstriction in children

Montelukast is recommended to be taken in the evening. The effectiveness of this drug to prevent exercise-induced bronchoconstriction (EIB) in children was already evaluated. However, there is no information to determine if this effectiveness could vary depending on dosage time. Children (n = 24) with a documented history of EIB performed an exercise challenge test before starting montelukast treatment. Twelve children were randomly allocated to receive the drug in the morning for 2 weeks, and another 12 to receive it in the evening. After this treatment period and after a week of washout, the children were crossed over. An exercise test was repeated after the first and second periods of treatment. Values obtained after morning or evening dosage were compared with pretreatment values for the whole group of children. There was a significant effect of montelukast for protecting against EIB, measured both as percent of maximum fall in forced expired volume in 1 sec (FEV1) (18.9 +/- 9.7, morning, 18.7 +/- 11.3, evening, vs. 27.5 +/- 9.8, pretreatment; P < 0.05) or as area under the curve (156.4 +/- 102.0, morning, 145.4 +/- 130.6, evening, vs. 294.3 +/- 156.5, pretreatment; P < 0.005). There were no statistical differences between taking the drug in the morning or evening. In conclusion, montelukast, taken for 2 weeks, is equally effective in exercise-induced bronchoconstriction when dosing either in the morning or in the evening.

Exaled nitric oxide and air trapping correlation in asthmatic children

Exhaled nitric oxide (eNO) levels have been shown to correlate with atopy and with airway hyperresponsiveness but not with standard spirometry. The aim of our study was to evaluate the correlation between eNo levels and functional residual capacity (FRC), residual volume (RV), RV to total lung capacity (TLC) ratio, and pulmonary resistances in asthmatic children ages 6-13 years. Forty-nine patients (35 males) were enrolled in the study. Nineteen of them were not receiving inhaled corticosteroids. The eNO levels were measured by chemiluminescence's analyzer and lung function study were performed by body box plethysmography. As expected, there was no correlation between eNO levels and forced vital capacity (FVC); forced expiratory volume in the first second (FEV1); mid respiratory flow between 25 and 75% of the vital capacity (MEF(25 -75)), FEV1/FVC, and pulmonary resistances. Instead a correlation was found between eNO level and RV both considering all the study population together (r = 0.51, P = 0.001) and separately the asthmatic children not receiving ICS (r = 0.6, P = 0.003). In the patients receiving ICS the correlation was still present (r = 0.43, P = 0.01). The correlation between eNo levels and RV may reflect the effect of airway inflammation on NO production and diffusion as well as peripheral airway trapping and consequent RV.

Understanding mild persistent asthma in children: the next frontier

Limitations in asthma prevalence studies and difficulties in diagnosing pediatric asthma lead to uncertainty over the full extent of mild persistent asthma in children and adolescents. Although recent surveys have reported that the majority of pediatric patients with asthma in the United States and Europe have symptoms consistent with mild disease, these surveys have limitations in design. Thus, the true prevalence of mild asthma remains unknown. It is unclear whether children with mild persistent asthma progress to more severe asthma, but the risk of severe asthma exacerbations seems to be unrelated to the symptom severity. Clinical studies restricted to pediatric patients with mild asthma are limited, but available data do suggest substantial morbidity of mild persistent asthma in this population and support inhaled corticosteroid intervention. There is a need for further investigation into the true prevalence of mild persistent asthma in children and adolescents, and optimal treatment.

Monitoring response to treatment in asthma management: food for thought

Asthma is a chronic inflammatory disorder of the airways that is characterized by episodic symptoms. In this regard, asthma management has classically involved periodic re-assessment by the health-care provider, during which therapy is altered mainly based on clinical and physiological parameters, such as assessment of symptoms, spirometry and peak expiratory flow monitoring. In this context, various markers of airway inflammation (e.g. eosinophils in the induced sputum, nitric oxide in the exhaled air) have been proposed to assess the severity of asthma and to adjust the therapy accordingly. The evaluation of airway hyper-responsiveness with different stimuli has also been suggested as a new tool to monitor asthma. However, the lack of definite relationships between airway inflammation and asthmatic symptoms strongly limit the use of markers of asthma severity in the clinical setting. Therefore, the need of new tools to assess the severity of asthma is raised. The ideal measurement employed to establish the proper asthmatic therapy should be safe, non-invasive, easy to perform, reproducible and accurate, and have the capability to monitor the changes induced by the therapeutic interventions. A careful review of the available techniques, and the evaluation of their sensitivity and specificity in the clinical setting is warranted.

Monitoring pulmonary function in asthma and COPD: point-of-care testing

OBJECTIVE

To provide pharmacists and other healthcare providers with a better understanding of new monitoring technologies for asthma and chronic obstructive pulmonary disease (COPD) available to clinics and pharmacies.

DATA SOURCES

Forty scientific articles were identified through a MEDLINE search (1990-June 2003), additional references listed in articles, and abstracts from scientific meetings.

STUDY SELECTION AND DATA EXTRACTION

English-language literature of controlled human clinical studies was reviewed to evaluate the accuracy, reliability, validity, and response of the new monitoring technologies.

DATA SYNTHESIS

The In-Check DIAL is a pulmonary airflow meter that identifies the most appropriate inhaler for a patient and is useful in determining how efficiently patients use their inhalers. Electronic peak flow meters such as the AirWatch, VMX Wright Mini-Log, PiKo-1, and electronic asthma monitor store and download multiple pulmonary function test (PFT) readings to a personal computer, allowing easy identification of patients who are fabricating results. The AirWatch also has the ability to measure forced expiratory volume in 1 second. The Spirophone AG-SP, VM Plus, and Micro DiaryCard spirometer are portable spirometers that can be used at home without the need for supervision. Bronchial challenge tests have been recently standardized and may prove to be beneficial in modifying drug therapy in patients with asthma and COPD.

CONCLUSIONS

Despite recent advances in medical technology, monitoring of asthma and COPD has not changed significantly. PFTs continue to be the gold standard for evaluating airway obstruction and/or restriction. Clinical trials that will evaluate outcomes such as decreased number of hospitalizations, emergency department visits, unscheduled visits to physicians, and days absent from school or work are needed to determine the utility of new monitoring technologies.

Exercise-induced bronchospasm in children: comparison of FEV1 and FEF25-75% responses

The response of asthmatic children to exercise has usually been evaluated by forced expiratory volume in 1 sec (FEV(1)). We reasoned that other respiratory indexes derived from the forced vital capacity maneuver such as forced expiratory flow between 25-75% of vital capacity (FEF(25-75%)) would add significant information in the evaluation of the relationship between asthma severity and response to exercise. We studied 164 children with intermittent (n = 63), mild persistent (n = 30), moderate persistent (n = 40), and severe persistent asthma (n = 31). Subjects exercised for 6 min on a cycle ergometer at 80% of their maximum heart rate, and spirometry was performed before and 5, 10, and 20 min after exercise. There was good correlation between changes in FEV(1) and FEF(25-75%) after exercise (r = 0.60, P < 0.001 for intermittent asthma and r = 0.80, P < 0.001 for severe persistent asthma). The presence of a fall in both FEV(1) (>/=10%) and in FEF(25-75%) (>/=26%) when compared to a decrease in only one of these two indexes was significantly greater in children with more severe asthma (60.0% for intermittent asthma and 94.4% for severe persistent asthma, P = 0.022). FEF(25-75%) can decrease in response to exercise without changes in FEV(1), mainly in children with mild asthma. In the evaluation of the response to exercise in children with different asthma severities, more than one maximum expiratory flow-volume parameter should be used.

Symptom perception in childhood asthma: how accurate are children and their parents?

Accurate symptom perception on the part of the patient is a critical component of asthma management. Limited data are available about how accurate children and their parents are in evaluating asthma symptoms. This study was designed to determine the symptom perceptual accuracy of families and to identify risk factors associated with inaccurate symptom perception. One hundred children (6-19 years) and their parents evaluated symptoms using subjective (visual analog scales) as well as objective (peak expiratory flow rates) measures of symptom severity. Accuracy was evaluated by comparing the match in zones (based on NHLBI clinical practice guidelines) indicated on the subjective measure with the objective measure. Children and parents were inaccurate about one-third of the time overall. Poor and minority families initially appeared to be less accurate; however, when we adjusted for the child's illness severity, these sociodemographic features were no longer significant risk factors. Children were as accurate as parents. When we evaluated symptom accuracy at "sick times" (when the child's peak flow reading was <80% personal best) accuracy decreased markedly to only about one-third of the episodes being correctly evaluated.

Polyclonal and allergen-induced cytokine responses in adults with asthma: resolution of asthma is associated with normalization of IFN-gamma responses

BACKGROUND

Atopic disease is associated with skewing of immune responses away from a T(H)1 toward a T(H)2 profile. Previous studies have implicated this cytokine imbalance in the development of disease. However, it is not known whether normalization of this imbalance is conversely associated with disease resolution.

OBJECTIVE

To further delineate the role of reduced T(H)1 and increased T(H)2 cytokine production in the pathogenesis of atopic disease and to determine whether disease resolution is associated with alteration of cytokine profiles, we investigated cytokine responses in a cohort of adult patients with asthma followed from childhood.

METHODS

A cohort of wheezy children and control subjects aged 7 to 10 years were recruited from 1964 to 1967. Subjects were reevaluated every 7 years to monitor the outcome of childhood asthma. At the 42-year follow-up, 89 subjects from this cohort were evaluated for mitogen and house dust mite (HDM)-induced T(H)1 (IFN-gamma) and T(H)2 (IL-4, IL-5, and IL-13) cytokine responses. Cytokine responses were compared in patients with ongoing asthma, patients with resolved asthma, and control subjects.

RESULTS

Patients with severe ongoing asthma had significantly reduced HDM-induced IFN-gamma production compared with that of control subjects and patients with resolved asthma. In contrast, HDM-induced IFN-gamma production in patients with resolved asthma was equivalent to that seen in control subjects. Patients with ongoing and resolved asthma produced significantly higher levels of IL-5 in response to HDM compared with that seen in control subjects, with levels being equivalent in patients with active and resolved asthma. HDM-induced IL-13 production was significantly increased in the patients with resolved asthma when compared with that seen in the control subjects. PHA-induced cytokine responses did not parallel HDM-induced responses.

CONCLUSION

Patients with persistent and severe atopic asthma have a reduced HDM-induced T(H)1 response, whereas those with resolved asthma do not. This suggests that reduced HDM-induced IFN-gamma production might be an important factor contributing to ongoing severe asthma and that normalization of allergen-induced T(H)1 responses might be important for disease resolution. The finding that all subjects with a history of asthma displayed increased HDM-induced T(H)2 (IL-5 and IL-13) cytokine responses, irrespective of the presence or absence of asthma, suggests that increased T(H)2 responses reflect the presence of the atopic state per se rather than being specifically linked to asthma.

Mite avoidance can reduce air trapping and airway inflammation in allergic asthmatic children

BACKGROUND

We investigated the effects of prolonged allergen avoidance in 18 house dust mite-sensitized asthmatic children during a prolonged residential period at a high altitude, allergen-free environment.

METHODS

Evaluations of residual volume (RV) and exhaled nitric oxide (eNO) were performed (i) at admission to the residential house in September, (ii) in December after 3 months of stay, (iii) in January after 15 days at home, exposed to allergens, and (iv) in June after 9 months of stay.

RESULTS

During the study period RV showed a significant decrease in December (from 117.5 +/- 7.7% to 96.5 +/- 3.2%) (P < 0.02) and a following increase in January (126.2 +/- 17.2%), after allergen re-exposure (P < 0.03). RV decreased again in June at the end of the study period (91.1 +/- 6.0%) (P = 0.001). FEV(1), FEF(25-75) and VC values did not present significant variations. ENO showed a significant decrease in December after 3 months at high altitude (from 21.3 +/- 3.9 p.p.b. to 11.9 +/- 1.7 p.p.b.) (P = 0.03), but no further significant change. No correlation was found between lung volumes and eNO, probably reflecting different aspects of asthma.

CONCLUSIONS

Results suggest that RV may be more sensitive than other respiratory function parameters in identifying children with air trapping, being influenced significantly as the inflammatory indices by effective allergen avoidance/exposure regimen.

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

OBJECTIVES

To compare the acceptability, reproducibility, and sensitivity of spirometric outcome measures of airway caliber during challenge testing in children.

DESIGN

FEV(1), forced expiratory volume in 0.75 s, forced expiratory volume in 0.5 s, and peak expiratory flow (PEF) were recorded during stepwise dosimetric histamine challenge tests. The responses were compared, and the reproducibility at baseline and from duplicate measurements at each challenge step was determined.

PATIENTS

One hundred five children with newly diagnosed asthma, aged 5 to 10 years.

RESULTS

Compared to PEF, FEV(1) showed better baseline reproducibility (p = 0.002) and higher sensitivity (p < 0.0001) during challenge testing, determined as the change normalized to the baseline variation, while the forced expiratory volumes were not significantly different in these respects. During challenge testing in subjects with acceptable flow-volume tracings, paired recordings of FEV(1) agreed within 0.1 L in 85% and within 0.2 L in 93% of measurements. During challenge testing, the reproducibility of FEV(1) measurements was not better than that of the other indexes. Failure to exhale long enough precluded the use of FEV(1) in 16 of the children, particularly the youngest children.

CONCLUSIONS

The results demonstrated that the recently published guidelines for FEV(1) measurements during challenge tests can be applied to children. During challenge tests in asthmatic children, the advantage of the shorter fractions of forced expiratory volume was that they were more often acceptably recorded than FEV(1), while they showed as good reproducibility and were also equally sensitive in assessing changes in airway obstruction.

Can peak expiratory flow measurements estimate small airway function in asthmatic children?

BACKGROUND

Asthma is characterized in part by small airways dysfunction. Peak expiratory flow (PEF) measurement has been suggested by all international guidelines as an important tool in asthma management. The correlation between PEF and FEV(1) but not with forced expired flow at 50% of vital capacity (FEF(50)) is well-established.

STUDY OBJECTIVE

To determine the value of PEF measurement as a predictor of small airways status as expressed by FEF(50).

DESIGN

Analysis of the association between PEF and FEF(50) in single and multiple determinations.

PATIENTS

One hundred eleven asthmatic children (mean age, 11.8 years), grouped in the following way according to FEV(1) values: within normal range (n = 46); mildly reduced FEV(1) (n = 44); and moderately/severely reduced FEV(1) (n = 21).

RESULTS

Overall, FEF(50) and PEF were significantly correlated (r = 0.49; p < 0.0001). However, in 41.6% of the patients, the actual FEF(50) differed by > 20% from the calculated FEF(50). PEF has a high specificity (82.4%) but a poor sensitivity (51.7%) to detect FEF(50) status. PEF was better able to reflect abnormal FEF(50) in the patients with more severe asthma and to reflect normal FEF(50) values in the healthier patients. In patients with multiple measurements (n = 40), the correlation between FEF(50) and PEF was significantly better than that derived from a single determination (multiple measurements r = 0.77; single measurement, r = 0.49).

CONCLUSIONS

Although PEF is an important tool in the management of asthmatic patients, it does not yield a complete picture because it is not sensitive in detecting small airways function. It is best used at home along with regular spirometry measurements at the clinic. PEF may serve as a better index of changes in small airways function once an individual regression is determined.

A comparison of the efficacy and safety of a half dose of fluticasone propionate with beclamethasone dipropionate and budesonide in childhood asthma

This study was carried out in an attempt to compare the efficacy and safety of fluticasone propionate (FP) at the half dose of budesonide (BUD) and beclamethasone dipropionate (BD) in childhood asthma. Ninety-six children with moderate to severe asthma (9.6 +/- 2.17 years) whose asthma was already controlled on BUD (n = 52) or BD (n = 44) were recruited into the study. In the first part of the study (the first 12 weeks) each group was followed with three weekly lung function measurements, daily diary records, and peak expiratory flow (PEF) measurements on the initial medication. At the end of 6 weeks, drugs were switched to a half dose of FP, and the subjects were followed for another 6 weeks. Blood samples were obtained for osteocalcin and plasma cortisol levels after each treatment period. In the second part of the study, 50 patients continued to take FP at the half dose of BUD or BD for another 30 weeks. Clinic visits, including lung function and PEF measurements, were conducted every 10 weeks. After 6 weeks of FP treatment, there was a small but statistically significant decrease in FEV1 and FEF(25-75) in both groups (BUD and BD) without any significant obstruction. These mild changes in lung function measurements continued during long-term follow-up. However, there was no statistically significant further decrease in any lung function parameters while receiving FP (visits 3-8) (coefficient = -0.00751 L/day, p = 0.39 for FEF(25-75) and coefficient = -0.00910 L/sec/day, p = 0.055 for FEV1). There were no significant changes in the morning and evening PEF measurements and diurnal PEF variations after 6 weeks of treatment with FP compared with BUD and BD treatments. There were no significant changes in basal cortisol and osteocalcin levels before or after 6 weeks of FP treatment (p > 0.05). The present study concluded that, although FP at the half dose of BUD or BD seems to maintain reasonable control of the disease symptoms, a mild but significant and persistent decrease in lung function parameters may indicate that FP may not be twice as potent as BUD or BD in childhood asthma by evaluation of lung functions. This conclusion must be further verified with long-term studies.

Children's perception of breathlessness in acute asthma

AIM

To determine whether asthmatic children who present to hospital with hypoxia perceive breathlessness less well than non-hypoxic presenters.

METHODS

A total of 27 children aged 5-16 years (mean age 10) admitted with acute asthma had recordings of oxygen saturation (SaO(2)), clinical score, forced expiratory volume in one second (FEV(1)), and breathlessness score (HMP) at admission and at 5, 10, 24, 48, and 72 hours after admission. Those defined as hypoxic (SaO(2) <92%) at admission were compared with a non-hypoxic group.

RESULTS

Twelve children were hypoxic at admission. Compared with the non-hypoxic group they were younger (8.6 (SD 2.8) v 11.2 (2. 8) y, p = 0.02), and had greater airway obstruction (FEV(1) 32.5 (10)% v 54.3 (26)%, p = 0.0073, 95% confidence interval (CI) -36.9 to -6.6) yet had a trend towards less breathlessness (median HMP 4 v 3, p = 0.062, CI -0.001 to 2.00) at admission. The hypoxic group had a smaller change in breathlessness from admission to discharge, despite a similar improvement in FEV(1), reflected in a lower ratio of change in HMP to change in FEV(1) (DeltaHMP/DeltaFEV(1)) (median DeltaHMP/DeltaFEV(1) 0.021%(-1) v 0.073%(-1), p = 0.0081, CI -0.075 to -0.016). Linear regression analysis showed a strong relation between DeltaHMP/DeltaFEV(1) and initial SaO(2) (p = 0.004, r = 0. 54).

CONCLUSIONS

Asthmatic children who present to hospital hypoxic tend to perceive themselves as less breathless than non-hypoxic children. This may predispose to a future life threatening attack.

Relationship between clinical signs and lung function in horses with recurrent airway obstruction (heaves) during a bronchodilator trial

During a trial to determine the dose response to the beta2-adrenergic agonist pirbuterol, we judged the severity of airway obstruction by use of a clinical scoring system and compared this to objective data obtained by quantitative measures of lung function. Six horses affected by recurrent airway obstruction were used in this trial. Four hundred and sixty-eight measurements of lung function and clinical scores were obtained from 13 measurement periods when horses received each of 6 doses of pirbuterol. Scores of 1-4 were assigned to degree of nasal flaring and abdominal effort and summed for a total score. The veterinarian scoring the signs did not know the dose of pirbuterol received by the horse and was unaware of the lung function data. Nasal, abdominal and total scores were significantly related to changes in lung function and changes in breathing pattern. There were significant differences between total scores greater than 5 in indices that reflected changes in breathing strategy (peak inspiratory and expiratory flow), peripheral airway obstruction (dynamic elastance), and effort of breathing (maximal change in pleural pressure). Below a total score of 5, there were fewer significant differences in lung function even though measurements of pulmonary resistance and dynamic elastance indicated considerable airway obstruction. Failure of clinical score to reflect this low-grade airway obstruction suggests that airway disease is underdiagnosed and its detection would be helped by the availability of a convenient lung function test.

Structural consequences of airway inflammation in asthma

Asthma represents a chronic inflammatory process of the airways followed by healing, the end-result of which is an altered structure referred to as a remodeling of the airways. Repair usually involves 2 distinct processes: regeneration (which is the replacement of injured tissue by parenchymal cells of the same type) and replacement by connective tissue and its eventual maturation into scar tissue. In many instances both processes contribute to the healing response and inflammation. In asthma the processes of cell dedifferentiation, migration, differentiation, and maturation and connective tissue deposition can be followed either by complete or altered restitution of airway structure and function, the latter often seen as fibrosis and increase in smooth muscle and mucus gland mass. These features result in an increased resistance to airflow, particularly when there is bronchial contraction and bronchial hyperresponsiveness. The effect on airflow is compounded by the presence of increased mucous secretion and inflammatory exudate, which not only blocks the airway passages but also causes an increased surface tension that favors airway closure.

Can peak expiratory flow predict airflow obstruction in children with asthma?

STUDY OBJECTIVES

A recent trend in the treatment of asthma has been the widespread, independent use of peak expiratory flow (PEF). We examined whether PEF monitoring creates inaccuracies in assessment of children with moderate to severe asthma.

METHODS

We compared the negative predictive value of PEF in relation to the forced expiratory volume in 1 second (FEV(1)), and to the forced expiratory flow between 25% and 75% of the vital capacity (FEF(25-75%)) at different levels of air trapping as determined by the residual volume over total lung capacity ratio (RV/TLC).

RESULTS

The study included 244 patients, ages 4 to 18 years with all classes of asthma severity, with FEV(1) ranging from 28% to 134% of predicted value. We analyzed 367 sets of pulmonary function tests performed throughout a 3-year period. Thirty percent of patients with a normal PEF value had an abnormal FEV(1) or FEF(25-75%). As air trapping increased, the ability of a normal PEF to predict normal FEV(1) and FEF(25-75%) readings fell from 83% to 53%. The negative predictive value was significantly lower for patients with RV/TLC ratio >30 compared with patients with RV/TLC <30.

CONCLUSIONS

The results of this study suggest that it might be possible to identify children for whom the PEF is likely to give false-negative results. As air trapping increases, it causes the PEF to give misleading reassurance of normal pulmonary function. Furthermore, poor predictiveness of PEF is obtained when values 80% of predicted for age are considered normal.

Internet-based home asthma telemonitoring: can patients handle the technology?

STUDY OBJECTIVE

To evaluate the validity of spirometry self-testing during home telemonitoring and to assess the acceptance of an Internet-based home asthma telemonitoring system by asthma patients.

DESIGN

We studied an Internet-based telemonitoring system that collected spirometry data and symptom reports from asthma patients' homes for review by physicians in the medical center's clinical information system. After a 40-min training session, patients completed an electronic diary and performed spirometry testing twice daily on their own from their homes for 3 weeks. A medical professional visited each patient by the end of the third week of monitoring, 10 to 40 min after the patient had performed self-testing, and asked the patient to perform the spirometry test again under his supervision. We evaluated the validity of self-testing and surveyed the patients attitude toward the technology using a standardized questionnaire.

SETTING

Telemonitoring was conducted in patients' homes in a low-income inner city area.

PATIENTS

Thirty-one consecutive asthma patients without regard to computer experience.

MEASUREMENT AND RESULTS

Thirty-one asthma patients completed 3 weeks of monitoring. A paired t test showed no difference between unsupervised and supervised home spirometry self-testing. The variability of FVC (4.1%), FEV(1) (3. 7%), peak expiratory flow (7.9%), and other spirometric indexes in our study was similar to the within-subject variability reported by other researchers. Despite the fact that the majority of the patients (71%) had no computer experience, they indicated that the self-testing was "not complicated at all" or only "slightly complicated." The majority of patients (87.1%) were strongly interested in using home asthma telemonitoring in the future.

CONCLUSIONS

Spirometry self-testing by asthma patients during telemonitoring is valid and comparable to those tests collected under the supervision of a trained medical professional. Internet-based home asthma telemonitoring can be successfully implemented in a group of patients with no computer background.