Boulet L P, Morin D, Turcotte H
Unité de Recherche, Hôpital Laval, Sainte-Foy, Québec.
Clin Invest Med. 1990 Apr;13(2):60-6.
This study looked at seasonal fluctuations of airway responsiveness (AR) to methacholine and exercise in ten mild asthmatic and seven normal subjects. Each subject had a monthly methacholine inhalation test. An exercise challenge with measurement of expiratory flows was performed initially in the fall (F), then in winter (W), and in summer (S). Throughout the study, the subjects were asked to record on a diary card twice daily peak flow rates and respiratory symptoms, one week a month. Airway responsiveness to exercise and methacholine remained generally stable throughout the year, although an increase in respiratory symptoms occurred during fall and winter. The overall AR to methacholine was not significantly different during the different seasons (F, W, S and Spring) with the methacholine concentration producing a 20% fall in FEV1, PC20 (mg/ml) values, respectively, of 1.7 +/- 1.2 mg/ml, 1.8 +/- 1.1, 2.1 +/- 1.2, and 2.0 +/- 1.9 for asthmatics and 79.0 +/- 1.2 mg/ml, 66.8 +/- 1.0, 87.3 +/- 1.0, and 73.1 +/- 1.0 for normals. However, short term variations in AR were associated to exposure to antigens and cold weather. Mean daily peak expiratory flows remained generally stable through the seasons. On the three exercise tests, the VO2 max and the mean % fall in FEV1 after maximal exercise showed large variations; these, however, were not significantly different (mean fall: 16.2% (F), 16.6% (W), and 14.7% (S) in asthmatics). In conclusion, although it may increase transiently, overall airway responsiveness to methacholine and exercise remains generally stable in asthmatic and normal subjects throughout the year.
本研究观察了10名轻度哮喘患者和7名正常受试者气道对乙酰甲胆碱和运动的反应性（AR）的季节性波动。每位受试者每月进行一次乙酰甲胆碱吸入试验。最初在秋季（F）、然后在冬季（W）和夏季（S）进行运动激发试验并测量呼气流量。在整个研究过程中，要求受试者每月有一周每天两次在日记卡上记录峰值流速和呼吸道症状。气道对运动和乙酰甲胆碱的反应性全年总体保持稳定，尽管在秋冬季节呼吸道症状有所增加。不同季节（F、W、S和春季）哮喘患者乙酰甲胆碱浓度使第一秒用力呼气容积（FEV1）下降20%时的总体AR无显著差异，PC20（mg/ml）值分别为1.7±1.2mg/ml、1.8±1.1、2.1±1.2和2.0±1.9，正常人为79.0±1.2mg/ml、66.8±1.0、87.3±1.0和73.1±1.0。然而，AR的短期变化与抗原暴露和寒冷天气有关。每日平均峰值呼气流量在各季节总体保持稳定。在三次运动试验中，最大摄氧量（VO2 max）和最大运动后FEV1的平均下降百分比变化很大；然而，这些差异无统计学意义（哮喘患者平均下降：秋季16.2%、冬季16.6%、夏季14.7%）。总之，尽管可能会短暂增加，但哮喘患者和正常受试者气道对乙酰甲胆碱和运动的总体反应性全年总体保持稳定。
