氦气自1935年Barach首次用其改善患者的气道阻塞以来,主要披用于上部气道阻塞或诊断研究。但其治疗作用一直未能完全发掘。氦气是一种惰性气体,无支气管扩张或抗炎作用。湍流时气道阻力直接与气体密度相关。氦气由于较氧气或氮气密度低,而能使气道阻力降低。此外氦气可降低雷诺数从而使部分气道的湍流变为层流进一步降低气道阻力。气道阻力降低最终使呼吸功减少。近年来哮喘的死亡率上升,而急 Helium has been primarily used for upper airway obstruction or diagnostic studies since Barach first used it to improve airway obstruction in 1935. However, its therapeutic effect has not been fully explored. Helium is an inert gas with no bronchodilation or anti-inflammatory effects. Airway resistance is directly related to gas density in turbulent flow. Helium reduces airway resistance due to its lower density than oxygen or nitrogen. In addition, helium can reduce the Reynolds number, so that part of the airway turbulence into laminar flow to further reduce airway resistance. Reduced airway resistance eventually reduces the work of breathing. In recent years, the mortality rate of asthma has risen, and the urgency