Methacholine Dose-Response Slopes from Maximal Bronchial Challenge Tests in Asthmatic Children: Methodological Aspects

To determine whether the slope of a maximal bronchial challenge test (in which FEV1 falls by over 50%) could be extrapolated from a standard bronchial challenge test (in which FEV1 falls up to 20%), 14 asthmatic children performed a single maximal bronchial challenge test with methacholin(dose range: 0.097–30.08 umol) by the dosimeter method. Maximal dose-response curves were included according to the following criteria: (1) at least one more dose beyond a FEV1 ù 20%; and (2) a MFEV1 ù 50%. PD20 FEV1 was calculated, and the slopes of the early part of the dose-response curve (standard dose-response slopes) and of the entire curve (maximal dose-response slopes) were calculated by two methods: the two-point slope (DRR) and the least squares method (LSS) in % FEV1 × umol−1. Maximal dose-response slopes were compared with the corresponding standard dose-response slopes by a paired Student’s t test after logarithmic transformation of the data; the goodness of fit of the LSS was also determined. Maximal dose-response slopes were significantly different (p < 0.0001) from those calculated on the early part of the curve: DRR20% (91.2 ± 2.7 FEV1% z umol−1)was 2.88 times higher than DRR50% (31.6 ± 3.4 DFEV1% z umol−1), and the LSS20% (89.1 ± 2.8% FEV1 z umol−1) was 3.10 times higher than LSS 50% (28.8 ± 1.5%FEV1 z umol−1). The goodness of fit of LSS 50% was significant in all cases, whereas LSS 20% failed to be significant in one. These results suggest that maximal dose-response slopes cannot be predicted from the data of standard bronchial challenge tests.

Bronchial Asthma in Children: Clinical and Epidemiologic Approach in Different Portuguese Speaking Countries

BACKGROUND: Geographical differences in asthma prevalence are currently accepted, but evidence is sparse due to the lack of multicentre studies using the same protocol. OBJECTIVES: To compare the prevalence of asthma and atopy among schoolchildren from Portuguese speaking countries (ISAAC and Portuguese Study) and evaluate some environmental variables, such as house dust mite exposure. MATERIAL AND METHODS: Significant random samples of schoolchildren studied with standard validated methods--questionnaires, skin prick tests, methacholine bronchial challenge tests; dust bed sampling for analysis of mite antigens. RESULTS: In the ISAAC study, in the 13-14 year-old age group, statistical significant differences were found, with higher wheezing prevalence in Brazil than in Portugal (two-fold). In the Portuguese Study, atopy prevalence ranged between 6.0 and 11.9% in Sal and S. Vicente (Cape Verde), up to 48.6 and 54.1% in Macau and Madeira. Active asthma had the higher values in Madeira (14.6%), and the lower in Macau (1.3%). Cape Verde had intermediate asthma prevalence (10.6 and 7.0%). The bronchial challenge test was positive in 25, 66 and 70% of asthmatic children from Sal, S. Vicente and Madeira respectively. Significant HDM antigen concentrations (Der p1) were found in Cape Verde and Madeira. CONCLUSIONS: There are significant variations in asthma and atopy prevalence between these pediatric populations. The reasons remain under discussion, but genetics linked to race, seem to play a central role, modulated by environmental and lifestyle variables.

Impacto do Exercício Físico Combinado na Percepção do Estado de Saúde da Pessoa com Doença Pulmonar Obstrutiva Crónica

AIM: The aim of the study was to evaluate the effectiveness of a 10-week combined training programme (aerobic and strength exercise) compared to an aerobic training programme, and respiratory physiotherapy on COPD patients' health. METHODS: Fifty subjects with moderate to severe COPD were randomly assigned to two groups. Combined group (CG, n=25) who underwent combined training, and aerobic group (AG, n=25) who underwent aerobic training. These were compared with fifty COPD subjects who underwent respiratory physiotherapy, breathing control and bronchial clearance techniques (RP group, n = 50). We evaluated health state through two questionnaires, St. George's Respiratory Questionnaire (SGRQ) and SF-36, at the beginning and at the end of the programme. RESULTS: The CG group showed differences (p<0.0001) in modification rates in state of health compared to the AG and RP groups in the activity (64 ± 9%, 19 ± 7%, 1 ± 15%) , impact (35 ± 5%, 20 ± 18%, 1 ± 14%) and total (41 ± 9%, 26 ± 17%, 1 ± 15%) domains assessed by the SGRQ, and the physical function (109 ± 74%, 22 ± 12%, 0.1 ± 18%), physical role (52 ± 36%, 11 ± 15%, 1.3 ± 21%) and vitality (83 ± 39%, 14 ± 38%) domains assessed by SF-36. CONCLUSION: These results suggest that combined training in subjects with COPD appears to be a more effective method, with better clinical changes, and improvements in health state perception.

Adolescents and School Asthma Knowledge and Attitudes

Introduction: bronchial asthma is a chronic disease that affects a high percentage of adolescents, with a significant restriction of daily activities, and is a cause of school absenteeism. The relationships between adolescents and asthma disease in school were assessed, with a view to improving knowledge about the asthmatic adolescent. Methods: a survey was conducted in the Lisbon metropolitan area, covering urban (Lisbon) and rural (Lourinh˜a ) zones and including 1879 students and 81 teachers from the 7th to 9th high school years. The study groups were asthmatic students, their peers, and teachers. A self-administered questionnaire was applied to collect information. The results were compared with a reference group of 91 asthmatic students attending our Department of Immunoallergy-Hospital Dona Estefânia. Cotinine urinary measurements were made in a sample of asthmatics and a control group. Results: the prevalence of current asthma among students was 10%. Estimates of asthma annual burden among 7th to 9th year students from Lisbon and Lourinh˜a high schools included 4,307 days missed from school, 4,148 medical consultations and a minimum of 351 hospital emergency care and 80 hospital admissions. Exposure to passive smoking was not significantly different between asthmatic students and theirs peers. Cotinine urinary measurements did not discriminate between exposed and non-exposed individuals. Cigarette smoking was almost as common among adolescent asthmatics (5.4%) as it was in non-asthmatic subjects (6.7%). However, 55% of asthmatics mentioned active and passive smoking as an asthma exacerbating factor. Asthmatic students, theirs peers and teachers showed a deficient knowledge about asthma (mean group scores: 17.6; 14.2 and 17.7 of a possible 30), particularly in the areas related to asthma recognition and its management. Asthmatics attending our Allergy Department had the highest scores. All groups showed tolerance in the sense of a positive and understanding attitude toward a person with asthma. However, traditional beliefs about asthma disease (dependence, inferiority...) were confirmed. A positive correlation between knowledge levels and tolerance attitudes was found. Conclusion: in view of the dimension of the asthma problem in adolescence and its social and economic impact, it is justifiable to assess the need for the implementation of asthma education programs in schools in order to improve asthma management by the adolescents and their schools.

Cystic Fibrosis, Atopy, Asthma and ABPA

The role of atopy on cystic fibrosis (CF) progression remains unclear but evidence suggests that it may influence the appearance of co-morbid conditions such as CF asthma or allergic bronchopulmonary aspergillosis (ABPA). Recognising asthma in patients with CF is not always easy but the identification of atopic markers favours the diagnosis. Physicians should be aware of this fact in order to achieve a better control of respiratory symptoms in patients with CF. Bronchial mucosa inflammation and abnormal mucus predispose to mould colonisation. These patients are at higher risk of allergic sensitisation, especially when atopic susceptibility is present. In the particular case of A. fumigatus, allergic sensitisation precedes ABPA development, which occurs in up to 10% of CF patients. Progression of lung function deterioration is most strikingly pronounced in patients with ABPA. Therefore, sensitisation with A. fumigatus should be regularly tested in patients with CF, especially those at higher risk. Recombinant allergens constitute an important advance in differentiating Aspergillus sensitisation from ABPA itself.