Inspired air is heated and humidified in the nose before it reaches lower airways. This mechanism is bypassed during tracheostomy, directly exposing the airways to colder and drier air from the environment, known to negatively affect mucociliary transport; however, little is known about how quickly mucociliary transport deteriorates. This study determines the short-term effect of flowing room air and nebulized hypertonic saline and mannitol on mucociliary transport in the trachea. In an ovine perfused in vitro tracheal model (N = 9) the epithelium was exposed to 25 L/min of flow, heated to lamb body temperature (38 °C) and fully saturated with water vapor as the control, followed by either room air (22 °C and 50% relative humidity) or nebulized solutions of NaCl 7% and mannitol 20% up to 1 min for a short duration, until mucociliary transport had visually changed. Mucus transport velocity (MTV) and cilia beat frequency (CBF) were continuously measured with video-microscopy. Exposing the tracheal epithelium to air heated to body temperature and fully humidified had stable MTV 9.5 ± 1.1 mm/min and CBF 13.4 ± 0.6 Hz. When exposed to flow of room air, MTV slowed down to 0.1 ± 0.1 mm/min in 2.0 ± 0.4 s followed by a decrease in CBF to 6.7 ± 1.9 Hz, after 2.3 ± 0.8 s. Both MTV and CBF recovered to their initial state when heated and humidified air-flow was re-introduced. Exposing the tracheal epithelium to nebulized hypertonic saline and nebulized mannitol for 1 min increased MTV without a subsequent increase in CBF. This study demonstrates mucociliary transport can deteriorate within seconds of exposing the tracheal epithelium to flowing room air and increase rapidly when exposed to nebulized hypertonic solutions. The reduction in MTV precedes slowing of CBF with room air and MTV increases without a subsequent increase in CBF during the nebulization. Their relationship is non-linear and a minimum CBF of approximately 6 Hz is required for MTV > 0, while MTV can reach 10.9 mm/min without CBF increasing. Clinically these findings indicate a potential rapid detrimental effect of breathing with non-humidified air via bypassed upper airways and the short-term effects of nebulized osmotic agents that increase MTV.

中文翻译：

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不受调节的室内空气或雾化的高渗盐水和甘露醇引起的气管上皮粘膜纤毛运输的快速变化不能通过跳动纤毛的频率来确定

吸入的空气在到达下呼吸道之前先在鼻子中被加热和加湿。在气管切开术中会绕过这种机制，直接将呼吸道暴露于环境中较冷和干燥的空气中，这已知会对粘膜纤毛运输产生负面影响；然而，人们对粘膜纤毛运输的恶化速度知之甚少。这项研究确定了流动的室内空气以及雾化的高渗盐水和甘露醇对气管粘膜纤毛运输的短期影响。在绵羊灌注的体外气管模型（N = 9）中，上皮暴露于25 L / min的流速下，加热至羔羊体温（38°C），并以水蒸气完全饱和作为对照，接着加入室内空气（在22°C和50％相对湿度下）或NaCl 7％和甘露醇20％的雾化溶液在短时间内持续1分钟，直到粘膜纤毛运输在视觉上发生了变化。用视频显微镜连续测量粘液运输速度（MTV）和纤毛搏动频率（CBF）。将气管上皮暴露于加热至体温并充分湿润的空气中，其稳定的MTV为9.5±1.1 mm / min，CBF为13.4±0.6 Hz。当暴露在室内空气中时，MTV在2.0±0.4 s内减速至0.1±0.1 mm / min，然后在2.3±0.8 s后将CBF降至6.7±1.9 Hz。当重新引入加热和加湿的气流时，MTV和CBF都恢复到其初始状态。将气管上皮暴露于雾化的高渗盐水和雾化的甘露醇1分钟可增加MTV，而CBF不会随之增加。这项研究表明，粘膜纤毛运输在使气管上皮暴露于流动的室内空气的几秒钟内会恶化，并在暴露于雾化的高渗溶液中后迅速增加。MTV的降低先于室内空气导致CBF降低，而MTV升高而雾化期间CBF却没有随之增加。它们之间的关系是非线性的，并且对于MTV> 0，至少需要约6 Hz的CBF，而MTV可以达到10.9 mm / min，而CBF不会增加。临床上，这些发现表明未加湿的空气通过旁路绕过上呼吸道可能具有潜在的快速有害影响，而雾化渗透剂的短期作用会增加MTV。MTV的降低先于室内空气导致CBF降低，而MTV升高而雾化期间CBF却没有随之增加。它们之间的关系是非线性的，并且对于MTV> 0，至少需要约6 Hz的CBF，而MTV可以达到10.9 mm / min，而CBF不会增加。临床上，这些发现表明未加湿的空气通过旁路绕过上呼吸道可能具有潜在的快速有害影响，而雾化渗透剂的短期作用会增加MTV。MTV的降低先于室内空气导致CBF降低，而MTV升高而雾化期间CBF却没有随之增加。它们之间的关系是非线性的，并且对于MTV> 0，至少需要约6 Hz的CBF，而MTV可以达到10.9 mm / min，而CBF不会增加。临床上，这些发现表明未加湿的空气通过旁路绕过上呼吸道可能具有潜在的快速有害影响，而雾化渗透剂的短期作用会增加MTV。