Análise das alterações de mecânica respiratória e da resposta broncodilatadora em crianças asmáticas por meio da Técnica de oscilações Forçadas

• Autor(a) principal: Souza, Georgia Alencar Franco de
• Data de Publicação: 2010
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/8688
• topic: Forced Oscillation Technique; Respiratory mechanics; Asthma. Astmatic children; Bronchodilator; Técnica de Oscilações Forçadas; Mecânica respiratória. Asma. Crianças asmáticas; Broncodilatador; Asma em crianças; CNPQ::CIENCIAS DA SAUDE::MEDICINA::CLINICA MEDICA::PNEUMOLOGIA

The increase of our knowledge about changes in respiratory mechanics and response to bronchodilator use in asthmatic children may contribute to a better understanding of this disease. The forced oscillation technique (FOT) has high potential in this sense, since it allows a detailed assessment of respiratory mechanics in asthmatic children. Thus, the objectives of this study are: (1) increase our understanding of the changes in respiratory mechanics of asthma in children, (2) investigate the clinical potential of FOT and (3) analyze the changes in respiratory mechanics resulting from bronchodilator response in asthmatic children. The present study examined 93 children, separated in the control group (n=31) and the asthmatic group divided according to the degree of airflow obstruction determined by spirometry in normal spirometry results (n=31) and with mild airway obstruction (n=31). Using the FOT we analyzed parameters related to the resistance of the respiratory system R0 (intercept resistance), Rm (resistance average) and S (slope of the resistance). R0 and Rm increased with airflow obstruction (p<0.002 and p<0.02, respectively) and S decreased (p<0.0007), indicating increased respiratory system non-homogeneity. There was a reduction in parameters related to the reactive properties of the respiratory system, Cst,sr (dynamic compliance, p<0.03) and Xm (reactance average, p<0,001) with increasing obstruction. The module of the respiratory system impedance at 4 Hz (| Zrs4Hz |) was also studied. This parameter is related to the total mechanical load on the respiratory system, and increased significantly with obstruction (p<0,001). Analyzing the diagnostic performance of FOT parameters, R0, Rm, Cst,sr and |Zrs4Hz| presented adequate values for clinical use in the identification of mild airway obstruction (AUC>0.7). These values were higher than that observed in the identification of the normal to the spirometric exam group, which may be related to the higher modifications in the group of children with mild airway obstruction. The bronchodilator response was studied by observing the differences within the same group of children, measuring the changes in each group before and after bronchodilator use. The parameters related to the resistance, R0, Rm and S showed significant improvement indicating reduced resistance in control group (p<0.00001,p<0.0003 e 0.00001), normal spirometry results (p<0.000002, p<0.00008 e 0.0006) and with mild airway obstruction (p<0.0001, p<0.0007 e 0.000001). These changes occurred in the control group and groups of children with asthma. Crs,din and Xm also showed significant changes in all groups studied in control group p<0.0001, p<0.00001), normal spirometry results (p<0.00006, p<0.00001) and with mild airway obstruction (p<0.0001, p<0.00001), a fact also observed in the analysis of | Zrs4Hz |, with showed a significant decrease in control group (p<0.00001), normal spirometry results(p<0.00001) and with mild airway obstruction (p<0.00001). We conclude that the increase of the degree of airflow obstruction in asthmatic children introduces increases in the resistance of the respiratory system, reductions in the dynamic compliance, reduction in homogeneity, as well as increase in the total respiratory system mechanical load. The FOT is able to detect respiratory changes in patients with mild airway obstruction. The use of bronchodilator medication introduces changes in asthmatic children, as well as in normal children. The results of the present study indicate that the FOT can be a sensitive test to evaluate the changes associated with asthma in children.