Thoracic Medicine, Concord Hospital, Sydney, AUSTRALIA.
Med Sci Sports Exerc. 2018 Feb;50(2):327-333. doi: 10.1249/MSS.0000000000001424.
Protective self-contained breathing apparatus (SCBA) used for firefighting delivers decompressed (cold) dehumidified air that may enhance the severity of exercise-induced bronchoconstriction (EIB) in those susceptible. We investigated the effect of SCBA during exercise on airway caliber in people with asthma and healthy controls.
Two exercise challenges (EC) designed to elicit EIB were performed on separate days within 1 wk. The initial challenge was breathing room air (ECRA) with workload titrated to elicit >60% estimated maximum voluntary ventilation. The exercise intensity was repeated for the second challenge using SCBA (ECSCBA). Forced expiratory volume in 1 s (FEV1) was measured before and up to 20 min after exercise. Bronchial hyperresponsivenss (BHR) to the hyperosmolar mannitol test was measured in the subjects with asthma.
Twenty subjects with current asthma (mean [SD]: age 27 [6] yr) and 10 healthy controls (31 [5] yr, P = 0.1) were studied. The percent fall in FEV1 after ECSCBA was greater in the mannitol-positive asthma subjects (14.4% [15.1%]) compared with mannitol-negative asthmatic subjects (1.6% [1.7%]; P = 0.02) and controls (2.3% [2.3%]; P = 0.04). The FEV1 response was not different between ECRA and ECSCBA (0.49% [5.57%]; P = 0.6). No BHR to mannitol (n = 7) was highly sensitive for identifying a negative response to ECSCBA (negative predictive value 100%).
The SCBA does not increase the propensity or severity for EIB in subjects with BHR. Those subjects with asthma but no BHR to inhaled mannitol did not exhibit EIB. The BHR to a hyperosmolar stimulus maybe considered a useful screening tool for potential recruits with a history of asthma.
用于消防的自给式正压呼吸器（SCBA）输送减压（冷）除湿空气，这可能会加重易患人群运动诱发的支气管收缩（EIB）的严重程度。我们研究了 SCBA 在运动过程中对哮喘患者和健康对照者气道口径的影响。
在 1 周内的不同天进行了两次旨在诱发 EIB 的运动挑战（EC）。初始挑战是在呼吸室气（ECRA）的情况下进行，工作负荷滴定至诱发> 60%的估计最大自愿通气量。第二次挑战使用 SCBA（ECSCBA）重复运动强度。在运动前和运动后 20 分钟测量 1 秒用力呼气量（FEV1）。对哮喘患者进行高渗甘露醇测试的支气管高反应性（BHR）进行了测量。
20 名患有哮喘的受试者（平均[标准差]：年龄 27 [6]岁）和 10 名健康对照者（31 [5]岁，P = 0.1）进行了研究。在甘露醇阳性哮喘患者中，ECSCBA 后 FEV1 的下降百分比（14.4%[15.1%]）明显大于甘露醇阴性哮喘患者（1.6%[1.7%]；P = 0.02）和对照组（2.3%[2.3%]；P = 0.04）。ECRA 和 ECSCBA 之间的 FEV1 反应没有差异（0.49%[5.57%]；P = 0.6）。对吸入性甘露醇无 BHR（n = 7）高度敏感，可识别对 ECSCBA 的阴性反应（阴性预测值 100%）。
SCBA 不会增加有 BHR 的受试者发生 EIB 的倾向或严重程度。那些对吸入性甘露醇无 BHR 的哮喘患者没有出现 EIB。对高渗刺激的 BHR 可能被认为是对有哮喘病史的潜在新兵进行筛选的有用工具。
