Estrechez relativa de las vías aéreas en ni？os con broncoespasmo inducido por el ejercicio

introduction: it has been recently described that the relationship between airways diameter and lung parenchyma is reflexed in the fef25-75/fvc ratio of spirometry. it has been observed that there is a relationship between the decrease in the fef25-75/ fvc ratio and bronchial hypereactivity to metacholine. bronchial reactivity to exercise is characteristic of asthma. in a population of asthmatic children we evaluated if a relationship existed between the fef25-75/fvc ratio and exercise induced bronchospasm (eib). population, material and methods. we recovered the exercise tests performed between 1998-2000 to 7-14 years asthmatic children, who had never received preventive treatment and with normal basal spirometry. the exercise test consisted in six minutes of free running; with spirometries before and 10 and 20 minutes after running. exercise-induced bronchospasm was assumed when the fev1 fell more than 15%. the tests were divided in two groups: positive eib and negative eib. in both groups we calculated the fef25-75/fvc ratio on basal spirometries. we compared the basal values of fvc, fev1, fev1/ fvc, fef25-75, and fef25-75/fvc. results. 74 tests were evaluated: 20 were positive eib and 54, negative eib tests. the analysis of fvc, fev1, fev1/fvc, and fef25-75 did not show significative differences. the fef25-75/fvc ratio was 0,77 ± 0,24 in the positive eib group and 0,91± 0,28 in the negative eib group (p<0,05). conclusion. the asthmatic children with positive eib showed a smaller fef25-75/fvc ratio, suggesting a relative narrowness of their airways