Lin C C, Wu J L, Huang W C, Lin C Y
Department of Internal Medicine, Mackay Memorial Hospital, Taipei, Taiwan.
J Asthma. 1991;28(1):31-40. doi: 10.3109/02770909109073368.
The authors compared the inhaled methacholine and exercise responses in 22 stable unmedicated asthmatic patients. The exercise and methacholine challenges were performed at one to three week intervals. Bronchial responsiveness to methacholine was measured in relation to the concentration of methacholine (PC20M). The response to exercise was expressed as the percentage of fall in FEV1 from the pre-exercise FEV1. The findings showed that 21 of 22 subjects demonstrated a fall in FEV1 of more than 20% after methacholine challenge, while only 9/22 subjects experienced a similar decrease in FEV1. All 9 of these positive response exercise cases completed three consecutive exercise challenges prior to the methacholine challenge. Of these cases, five were refractory to the repeated exercise challenge, and the PD20M at the nonexercise stage was significantly lower than the postexercise state. In fact, the methacholine challenge sensitivity actually decreased (PD20 increased) after repeated exercise. The authors concluded that methacholine seems to be a more sensitive bronchial provocation test than exercise. Second, only 55.6% of the exercise test-positive subjects were refractory to the second exercise challenge. Therefore, other factors besides the release of mediators should be considered in exercise-induced asthma. Third, methacholine sensitivity actually decreased (PD20 increases) after repeat exercise challenge.
作者比较了22例病情稳定且未用药的哮喘患者对吸入乙酰甲胆碱和运动的反应。运动和乙酰甲胆碱激发试验每隔1至3周进行一次。根据乙酰甲胆碱的浓度（PC20M）测定支气管对乙酰甲胆碱的反应性。运动反应以FEV1较运动前FEV1下降的百分比来表示。结果显示，22名受试者中有21名在乙酰甲胆碱激发试验后FEV1下降超过20%，而只有9/22的受试者FEV1出现类似下降。所有这9例运动试验阳性的病例在进行乙酰甲胆碱激发试验之前均完成了连续三次运动激发试验。在这些病例中，有5例对重复运动激发试验不敏感，非运动阶段的PD20M显著低于运动后状态。事实上，重复运动后乙酰甲胆碱激发试验的敏感性实际上降低了（PD20增加）。作者得出结论，乙酰甲胆碱似乎是比运动更敏感的支气管激发试验。其次，运动试验阳性的受试者中只有55.6%对第二次运动激发试验不敏感。因此，在运动诱发哮喘中，除了介质释放之外还应考虑其他因素。第三，重复运动激发试验后乙酰甲胆碱敏感性实际上降低了（PD20增加）。
