Objective: Asthma is the most common chronic pulmonary disease, characterized by bronchial inflammation. Some children with asthma have persistent pulmonary function impairment. The prevalence and etiology of this abnormality in children with asthma in developing countries remain unknown. The objective of this study was to estimate the proportion of patients with impaired pulmonary function who were unresponsive to treatment in a group of children and adolescents with asthma, and to describe the phenotypic characteristics of the sample. Methods: Using a standardized questionnaire, we selected outpatients (5-17 years of age) diagnosed with persistent asthma. These patients underwent spirometry and skin prick tests for sensitivity to common aeroallergens. Persistent pulmonary function impairment was defined as an FEV1/FVC ratio < 0.80, even after 10 days of treatment with bronchodilators and oral corticosteroids. We used the atopic index to differentiate between patients with little or no response to the skin prick test and those with a strong response (cut-off point: 4 allergens). Results: We included 96 patients with a mean age of 10.6 years. Of those, 52 (54.1%) were male, and 89 (92.7%) were atopic. Of the 96 patients, 8 (8.3%) had impaired pulmonary function even after the treatment. Among those patients, 8 (100%) were atopic, 7 (87.5%) had moderate or severe asthma, and 7 (87.5%) had a history of hospitalization for acute bronchiolitis. Conclusions: Children and adolescents with moderate or severe asthma can present with impaired pulmonary function and be unresponsive to treatment. This clinical situation has been little studied in developing countries, and its risk factors and etiology will be better understood only through birth cohort studies.

Keywords: Asthma; Respiratory function tests; Allergy and immunology.

Background: Several lung diseases are characterized by a predominantly neutrophilic inflammation. A better understanding of the mechanisms of action of some drugs on the airway inflammation of such diseases may bring advances to the treatment. Objective: To develop a method to induce pulmonary neutrophilic response in mice, without active infection. Methods: Eight adult Swiss mice were used. The study group (n = 4) received an intranasal challenge with 1 x 1012 CFU/ml of Pseudomonas aeruginosa (Psa), frozen to death. The control group (n = 4) received an intranasal challenge with saline solution. Two days after the intranasal challenge, a bronchoalveolar lavage (BAL) was performed with total cell and differential cellularity counts. Results: The total cell count was significantly higher in the group with Psa, as compared to the control group (median of 1.17 x 106 and 0.08 x 106, respectively, p = 0.029). In addition to this, an absolute predominance of neutrophils was found in the differential cellularity of the mice that had received the Psa challenge. Conclusion: The model of inducing a neutrophilic pulmonary disease using frost-dead bacteria was successfully developed. This neutrophilic inflammatory response induction model in Swiss mice lungs may be an important tool for testing the anti-inflammatory effect of some antimicrobial drugs on the inflammation of the lower airways.

Keywords: Animal experimentation. Lung disesases. Inflammation. Neutrophils. Pseudomonas.

Objective: To evaluate the acceptability and reproducibility of spirometry in preschool children; to estimate the effect size of early termination of exhalation (ETE) on FVC, FEV1 and FEV0.5; and to evaluate the validity of FEV0.5 in curves with ETE. Methods: Spirometric data were obtained from 240 healthy preschool children, who were selected by simple sampling. On the basis of the best curve from each child according to the end of exhalation, three groups were formed: no ETE (nETE); ETE and flow ≤ 10% of the highest PEF (ETE≤10); and ETE and flow > 10% of the highest PEF value (ETE>10). The reproducibility of FVC, FEV1 and FEV0.5 was compared among the three groups. The effect of ETE on FVC, FEV1, and FEV0.5 was assessed. Results: Of the 240 children tested, 112 (46.5%)-82 (34.0%) of those in the nETE group and 30 (12.5%) of those in the ETE≤10 group-had acceptable curves for all the parameters. In 64 (27.0%) of those in the ETE>10 group, the curves were acceptable only for FEV0.5, increasing the proportion of children with valid FEV0.5 to 73.0%. There were no significant differences between the nETE and ETE≤10 groups in terms of the mean values of the parameters assessed. Conclusions: Maneuvers with ETE and flow ≤ 10% of the highest PEF are valid. In individuals with a flow > 10% of the highest PEF value, these maneuvers are only valid for FEV0.5.

Keywords: Spirometry; Child, preschool; Vital capacity; Forced expiratory volume; Reproducibility of results.

Objective: The interrupter technique is used for determining interrupter resistance (Rint) during quiet breathing. This noninvasive method requires minimal cooperation and can therefore be useful in evaluating airway obstruction in uncooperative children. To date, no reference values have been determined for Rint in a Brazilian population. The objective of this study was to define a prediction equation for airway resistance using the interrupter technique for healthy children aged 3-13 years. Methods: This was a prospective, cross-sectional study involving preschool and school children in Porto Alegre, Brazil, in whom Rint was measured during peak expiratory flow. Results: ­One-hundred and ninety-three children were evaluated. Univariate analysis using linear regression showed that height, weight and age correlated significantly and independently with Rint. Multiple regression with height, weight, age and gender as variables resulted in a model in which only height and weight were significant, independent predictors of Rint. Collinearity was identified among height, weight and age. ­Conclusions: Reference values and an equation for calculating Rint in healthy children were obtained and are adjusted for height.

Keywords: Respiratory function tests; Airway resistance; Diagnostic techniques, respiratory system; Airway obstruction/diagnosis; Reference values.