潮湿空气会增加哮喘患者的气道阻力。
Humid air increases airway resistance in asthmatic subjects.
作者信息
Aitken M L, Marini J J, Culver B H
出版信息
West J Med. 1988 Sep;149(3):289-93.
Eight persons with asthma were exposed to seven air conditions varying in temperature (37 degrees C to 49 degrees C [98.6 degrees F to 120.2 degrees F]) and water content (44 mg H2O per liter to 79 mg H2Oper liter) . Normocapnic hyperventilation for three minutes at 40% maximal voluntary ventilation was carried out for each condition. A constant-volume body plethysmograph measured the functional residual capacity and specific airway conductance (SGaw), followed by two forced expiratory manuevers. Measurements were taken before and 1, 5, 10, and 20 minutes after each challenge. Air conditions with 100% relative humidity caused a fall in the SGaw that was maximal in 1 minute. Air conditions at 100% relative humidity caused a greater fall in both the forced expiratory volume in 1 second (FEV1) (P<.05) and the SGaw (P<.005) than did conditions of the same temperature but less water content. At 44 degrees C and 100% relative humidity, the mean percent change in FEV1 and SGaw was -2% and -40%, respectively, at 1 minute after challenge. Of the conditions examined, the optimal temperature was 44 degrees C, and we speculate that the optimal water content is less than 44 mg H2O per liter. Inhaled water concentrations exceeding 44 mg H2O per liter should probably not be used in patients with asthma.
八名哮喘患者暴露于七种温度（37摄氏度至49摄氏度[98.6华氏度至120.2华氏度]）和含水量（每升44毫克H₂O至每升79毫克H₂O）各不相同的空气环境中。在每种环境下，以40%的最大自主通气量进行三分钟的正常碳酸血症性过度通气。使用定容体容积描记器测量功能残气量和比气道传导率（SGaw），随后进行两次用力呼气动作。在每次激发前以及激发后1、5、10和20分钟进行测量。相对湿度为100%的空气环境会导致SGaw下降，在1分钟时降至最低。与相同温度但含水量较低的环境相比，相对湿度为100%的空气环境会使一秒用力呼气量（FEV1）（P<0.05）和SGaw（P<0.005）下降幅度更大。在44摄氏度和100%相对湿度条件下，激发后1分钟时FEV1和SGaw的平均变化百分比分别为-2%和-40%。在所研究的环境中，最佳温度为44摄氏度，我们推测最佳含水量低于每升44毫克H₂O。哮喘患者可能不应使用吸入水浓度超过每升44毫克H₂O的情况。
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