McFadden E R
Airway Disease Center, Case Western Reserve University School of Medicine, Cleveland, Ohio.
Am Rev Respir Dis. 1992 Nov;146(5 Pt 2):S8-10. doi: 10.1164/ajrccm/146.5_Pt_2.S8.
The intrathoracic airways of humans play a prominent part in conditioning inspired air. During inspiration the air is warmed and humidified by the movement of heat and water from the mucosa as a direct function of the temperature and vapor pressure gradients that exist. In this process, the mucosa is cooled. During expiration, the gradients are reversed, and heat and water are given back into the airways. At low levels of ventilation, most of the conditioning process takes place in the upper air passages; however, as ventilation rises, more and more of the tracheobronchial tree becomes involved, and incompletely conditioned air penetrates deeply into the distal airways before it is brought to equilibrium with body conditions. It is likely that the heat required to condition the inspired air is derived from the bronchial circulation, but this has not yet been definitely proved. In normal persons, the thermal events associated with the conditioning of inspired air do not produce any changes in pulmonary mechanics. In contrast, in asthmatics, the airway cooling of hyperpnea and the rapid rewarming that develops when hyperpnea is terminated evoke bronchoconstriction.
人类的胸内气道在调节吸入空气方面起着重要作用。在吸气过程中，空气通过热量和水分从黏膜的移动而被加热和加湿，这是温度和蒸汽压梯度直接作用的结果。在此过程中，黏膜会冷却。在呼气过程中，梯度反转，热量和水分又回到气道中。在低通气水平时，大部分调节过程发生在上呼吸道；然而，随着通气量增加，越来越多的气管支气管树参与进来，未完全调节的空气在与身体状况达到平衡之前就深入到远端气道。调节吸入空气所需的热量可能来自支气管循环，但这尚未得到确切证实。在正常人中，与调节吸入空气相关的热事件不会引起肺力学的任何变化。相比之下，在哮喘患者中，深呼吸时气道冷却以及深呼吸终止时迅速复温会引发支气管收缩。
