哮喘时造成支气管平滑肌收缩和气道壁增厚的原因极其复杂,其中包括气管上皮受损、血管漏、神经性反射及炎症细胞大量释放介质等。显然,不同的刺激可通过不同的机理引起支气管收缩,但这些机理中哪些因素是关键,尚不清楚。运动时支气管收缩与气道内热量丧失有关,这种效应是气道内温度改变的直接作用,还是气道内表面电介质改变的缘故尚有争论。当然维持气道内正常电介质的恒定是十分重要的,无论吸入低渗(如蒸馏水或“雾”)或高渗液体 Asthma causes bronchial smooth muscle contraction and thickening of the airway wall is extremely complex, including tracheal epithelial damage, vascular leakage, neurological reflex and inflammatory cells release a large number of media. Obviously, different stimuli may cause bronchoconstriction through different mechanisms, but it is unclear which of these mechanisms are the key. Bronchoconstriction during exercise is associated with loss of caloric heat in the airway. This effect is a direct result of temperature changes in the airway or changes in the dielectric on the inner surface of the airway. Of course, it is important to maintain the normal dielectric constant in the airway, regardless of whether hypotonic (eg distilled or “mist”) or hypertonic liquids