Testes de broncoprovocação com metacolina e com exercício em bicicleta e corrida livre em crianças com asma intermitente

Abstract

Suggested citation: Souza AC, Pereira CA. Bronchial provocation tests using methacholine, cycle ergometer exercise and free running in children with intermittent asthma. J Pediatr (Rio J). 2005;81:65-72. AbstractObjective: To compare airway responsiveness to methacholine, cycle ergometer exercise and free running in children with intermittent asthma.Methods: A randomized study was conducted with 30 children of both genders with intermittent asthma. Each child was submitted to challenge testing on three separate days, in random order: a) Methacholine challenge using a dosimeter; b) Exercise challenge testing free running along a 50-meter-long corridor; c) Dry-air exercise challenge on a cycle ergometer. Target heart rate during exercise was 80 to 90% of the maximum predicted value. Spirometry was performed 3, 6,10,15,20 and 30 minutes after exercise. Exercise-induced bronchospasm was defined as a decrease in FEV 1 of > 10% in comparison to pretest values.Results: Mean age was 11±3 years. FEV 1 and FEV 1 /FVC ratios were normal and similar before all provocation tests. The maximum heart rate was 178±7 bpm during cycling and 181±6 bpm during the free running test (p > 0.05). Significant bronchospasm was observed with methacholine in 23 cases, after free running in 19 and after cycling in 14 children (p < 0.05, methacholine vs exercise tests). Taking all FEV 1 measurements after exercise into account, the free running test resulted in greater exercise-induced bronchospasm in comparison with exercise made on a cycle ergometer (p = 0.003, χ 2 = 8.948). There was a significant, but poor, correlation between the maximum percentage decrease in FEV 1 after free running and cycling (r = 0.46, p < 0.01). Conclusions:Methacholine challenge identifies a greater number of asthmatics in comparison to exercise tests. When bronchial provocation test with methacholine is not available, free running should be the test of choice due to its simplicity and greater ability to induce bronchospasm. J Pediatr (Rio J). 2005;81(1):65-72: Asthma, bronchial provocation tests, methacholine chloride, exercise test, exercise-induced asthma.

Avaliação da capacidade de exercício em adolescentes asmáticos e saudáveis

“…The nose clip was used in both tests, as reported in other studies [21][22][23] , to simulate mouth breathing that these individuals demonstrated during physical effort. In addition, it allowed to investigate if the inspired drier air could change spirometric variables in the post-test, even in exercises of lower intensity, since the air humidity significantly influences the occurrence of EIB 23 . However, in the present study there were no decreases in the post-test FEV 1 , especially in the 6MST.…”

“…The 6MWT followed the standards of the ATS 20 . To ensure mouth breathing, a nose clip was used during the test, as recommended by other authors to check the occurrence of EIB [21][22][23] . The physical performance on the test was determined through the total walked distance (WD), in ms, and the maximal heart rate was obtained through the formula: HRmax=210-(0.65 x yrs of age) 5 .…”