We investigated the effects of heliox administration (80% Helium in O₂) on tidal inspiratory flow limitation (tIFL) occurring in supine anesthetized spontaneously breathing rabbits, regarded as an animal model of obstructive apnea-hypopnea syndrome. 22 rabbits were instrumented to record oro-nasal mask flow, airway opening, tracheal and esophageal pressures and diaphragm and genioglossus electromyographic activities while breathing either room air or heliox, and, in 12 rabbits, also during the application of continuous positive airway pressure (CPAP; 6 cmH2O). For the group, heliox increased peak inspiratory flow, ventilation (18±11%), peak inspiratory tracheal and dynamic transpulmonary pressures, but in no animal eliminated tIFL, as instead CPAP did in all. Muscle activities were unaffected by heliox. In the presence of IFL the increase in flow with heliox (ΔV̇IFL) varied markedly among rabbits (2 to 49%), allowing the distinction between responders and non-responders. None of the baseline variables discriminated responders and non-responders. However, fitting the Rohrer equation (R=K₁+K₂V̇) to the tracheal pressure-flow relationship over the first 0.1s of inspiration while breathing air allowed such discrimination on the basis of larger K₂ in responders (0.005±.002 vs 0.002±.001 cmH₂O·s²·ml^-2; p<0.001), suggesting a corresponding difference in the relative contribution of laminar and turbulent flow. The differences in ΔV̇IFL between responders and non-responders were simulated by modeling the collapsible segment of the upper airways as a non-linear resistor and varying its pressure-volume curve, length and diameter, thus showing the importance of mechanical and geometrical factors in determining the response to heliox in the presence of tIFL.

中文翻译：

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自发吸气流量受限的麻醉兔的Heliox给药

我们调查了氦氧混合气给药的效果（80％的氦气在O _2中）在仰卧麻醉的自发呼吸的兔子中发生的潮气吸入流量限制（tIFL），被认为是阻塞性呼吸暂停低通气综合征的动物模型。22只兔子被仪器记录在呼吸室内空气或氦氧混合气时口鼻面具流量，气道张开，气管和食道压力以及and肌和舌肌肌电图活动，并且在12只兔子中，持续施加持续气道正压（CPAP） ; 6 cmH2O）。对于该组，日程增加了峰值吸气流量，通气量（18±11％），峰值吸气气管压力和动态经肺压，但没有动物消除了tIFL，而CPAP却完全消除了。肌肉活动不受日光照射的影响。在存在IFL的情况下，家兔的日血流量增加（ΔV̇IFL）明显不同（2％至49％），允许区分响应者和非响应者。基线变量均不能区分响应者和非响应者。但是，拟合Rohrer方程（R = K₁ + K ₂ V）到超过吸气的第一0.1S而呼吸空气所允许的大小K的基础上这种歧视气管压力-流量关系₂在应答者（0.005±0.002 0.002 VS±0.001 CMH ₂ ö·s的² ·ml ^-2； p <0.001），表明层流和湍流的相对贡献存在相应的差异。通过将上呼吸道的可折叠段建模为非线性电阻器并更改其压力-体积曲线，长度和直径，来模拟响应者和非响应者之间的ΔV̇IFL差异，从而显示出机械和几何因素在确定中的重要性在tIFL存在下对氦氧混合气的反应。