Horstman D H, Seal E, Folinsbee L J, Ives P, Roger L J
Clinical Research Branch, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711.
Am Ind Hyg Assoc J. 1988 Jan;49(1):38-47. doi: 10.1080/15298668891379341.
The purpose of this study was to determine the shortest duration of exposure to 1.0 ppm sulfur dioxide (SO2) sufficient to induce bronchoconstriction significantly greater than that observed with exposure to clean air (CA) in exercising SO2-sensitive asthmatics. Asymptomatic, nonmedicated, male asthmatics (n = 12) with airway hyperresponsiveness to both methacholine and SO2 were exposed in a chamber (20 degrees C, 40% relative humidity) for 0.0, 0.5, 1.0, 2.0 and 5.0 min to both CA and 1.0 ppm SO2 on separate days (10 exposures). Just prior to each exposure, subjects walked on a treadmill in CA for 5 min at a predetermined speed/elevation to elicit a target ventilation of about 40 L/min, i.e., a brisk pace up a slight incline. After this walk, subjects rapidly entered an adjoining exposure chamber containing either CA or SO2 and immediately walked at the same speed/elevation for the specified exposure duration. Subjects then rapidly exited the chamber. Specific airway resistance (SRaw) and ratings of respiratory symptoms associated with asthma [shortness of breath/chest discomfort (SB/CD) and wheezing (WHZ)] were measured prior to any exercise and following each exposure. Postexposure SRaw and symptom ratings increased with increased exposure duration in SO2; postexposure SRaw also was increased with increased exposure duration in CA but to a lesser extent. After adjusting for the CA response, significantly greater SO2-induced bronchoconstriction was observed for the 2.0 and 5.0 min exposures as indicated by substantially greater increases in SRaw and substantially higher ratings of respiratory symptoms. The authors conclude that with the above exposure conditions, on average, SO2-sensitive asthmatics exhibit significant bronchoconstriction at exposure durations of 2.0 min or more.
本研究的目的是确定对于运动型二氧化硫（SO₂）敏感哮喘患者，暴露于1.0 ppm二氧化硫的最短时长，该时长足以诱发比暴露于清洁空气（CA）时显著更严重的支气管收缩。对乙酰甲胆碱和SO₂均有气道高反应性的无症状、未用药男性哮喘患者（n = 12）在一个舱室（20摄氏度，相对湿度40%）中，于不同日期分别暴露于CA和1.0 ppm SO₂ 0.0、0.5、1.0、2.0和5.0分钟（共10次暴露）。每次暴露前，受试者在CA环境中以预定速度/坡度在跑步机上行走5分钟，以引发约40升/分钟的目标通气量，即轻快地走上轻微斜坡。此次行走后，受试者迅速进入相邻的含有CA或SO₂的暴露舱室，并立即以相同速度/坡度行走指定的暴露时长。然后受试者迅速离开舱室。在任何运动前以及每次暴露后，测量特定气道阻力（SRaw）以及与哮喘相关的呼吸道症状评分[呼吸急促/胸部不适（SB/CD）和喘息（WHZ）]。暴露后SRaw和症状评分随SO₂暴露时长增加而升高；暴露后SRaw在CA中也随暴露时长增加而升高，但程度较小。在对CA反应进行校正后，对于2.0和5.0分钟的暴露，观察到SO₂诱发的支气管收缩显著更严重，表现为SRaw显著更大幅度增加以及呼吸道症状评分显著更高。作者得出结论，在上述暴露条件下，平均而言，SO₂敏感哮喘患者在暴露时长达到2.0分钟或更长时会出现显著的支气管收缩。
