Wilson Grant D, Sittig Steven E, Schears Gregory J
Department of Respiratory Care, Mayo Clinic, Rochester, Minnesota 55905, USA.
J Emerg Med. 2008 Feb;34(2):171-4. doi: 10.1016/j.jemermed.2007.04.026. Epub 2007 Nov 19.
The Laryngeal Mask Airway (LMA) is an accepted adjunct for airway management in emergency patients. There are a number of case reports describing its use in transport medicine for infant to adult patients, including during flight. Although studies of the effect altitude has on air-filled tracheal tubes exists, we were unable to find documentation of the effect of altitude on laryngeal mask airways. Our objective was to assess the effect of altitude on the LMA in both fixed wing and rotary wing models. We performed an in vitro study of the effect of altitude on the LMA cuff. Infant and adult airway trainer mannequins with properly sized and inserted LMA-Classic laryngeal mask airways were monitored for cuff pressure changes while flown at altitudes commonly encountered during air medical transport. Both models demonstrated that LMA cuff pressures may exceed manufacturer recommended levels for safe use even at the relatively low altitudes experienced during rotor wing flight. Properly inserted and inflated laryngeal mask airways at ground level may result in overinflated LMA cuffs when flown to altitudes commonly used for rotor and fixed wing medical transport unless monitored and corrected.
喉罩气道（LMA）是急诊患者气道管理中公认的辅助工具。有许多病例报告描述了其在从婴儿到成人患者的转运医学中的应用，包括在飞行过程中。虽然存在关于海拔对充气气管导管影响的研究，但我们未能找到海拔对喉罩气道影响的文献记录。我们的目的是评估海拔对固定翼和旋翼机模型中LMA的影响。我们对海拔对LMA套囊的影响进行了一项体外研究。在模拟空中医疗转运中常见的海拔高度飞行时，对配备尺寸合适且已插入LMA-Classic喉罩气道的婴儿和成人气道训练模拟人进行套囊压力变化监测。两个模型均表明，即使在旋翼机飞行中相对较低的海拔高度，LMA套囊压力也可能超过制造商推荐的安全使用水平。除非进行监测和校正，否则在地面正确插入并充气的喉罩气道在飞行到旋翼机和固定翼医疗转运常用的海拔高度时，可能会导致LMA套囊过度充气。
