Sanna A, Veriter C, Kurtansky A, Stănescu D
Pulmonary Laboratory and Division, Cliniques Universitaires Saint-Luc, Brussels, Belgium.
Sleep. 1994 Apr;17(3):220-5.
Upper airway muscles (UAM) are activated during inspiration, but little is known about their activity during expiration. We studied six healthy volunteers in supine position. Negative pressure (-10 to -30 cm H2O) was applied cyclically at the mouth during expiration. Subjects actively breathed during inspiration and either contracted or relaxed their UAM during expiration. Supraglottic pressure (Psg) was measured with a catheter with the tip at the supraglottic level. During relaxation, but not during contraction, there was expiratory flow limitation (FL) accompanied by high frequency pressure and flow oscillations (70 +/- 5.7 Hz at -30 cm H2O). The average linear supraglottic resistance was higher during relaxation than during contraction at both -10 and -20 cm H2O (p < 0.05), but not at -30 cm H2O. Amplitude of expiratory genioglossus electromyogram was 3.6 +/- 2.5 mm during quiet breathing, 7.0 +/- 3.8 mm during contraction (p < 0.05) and 4.1 +/- 1.8 mm during relaxation. Average mouth pressure, which immediately preceded pressure (and flow) oscillations was -2.1 +/- 0.9 cm H2O. In one subject cineradiography of the neck during expiratory application of -30 cm H2O showed anterior flexion and high frequency oscillations of the soft palate during relaxation. During contraction, the soft palate was close to the posterior pharyngeal wall without oscillations. We conclude that cyclically applied negative pressure at the mouth during expiration produced expiratory flow limitation during relaxation but not during contraction, and that expiratory contraction of UAM stabilizes upper airways during negative pressure application at the mouth.
上气道肌肉（UAM）在吸气时被激活，但关于其在呼气时的活动情况知之甚少。我们对6名仰卧位的健康志愿者进行了研究。在呼气时，在口腔处周期性施加负压（-10至-30 cm H₂O）。受试者在吸气时主动呼吸，在呼气时收缩或放松其UAM。使用尖端位于声门上水平的导管测量声门上压力（Psg）。在放松时而非收缩时，出现了呼气气流受限（FL），伴有高频压力和气流振荡（在-30 cm H₂O时为70±5.7 Hz）。在-10和-20 cm H₂O时，放松时的平均线性声门上阻力高于收缩时（p<0.05），但在-30 cm H₂O时并非如此。安静呼吸时呼气颏舌肌肌电图的幅度为3.6±2.5 mm，收缩时为7.0±3.8 mm（p<0.05），放松时为4.1±1.8 mm。紧接压力（和气流）振荡之前的平均口腔压力为-2.1±0.9 cm H₂O。在一名受试者中，在呼气时施加-30 cm H₂O时进行的颈部动态放射成像显示，放松时软腭向前弯曲并出现高频振荡。收缩时，软腭靠近咽后壁且无振荡。我们得出结论，呼气时在口腔处周期性施加负压在放松时产生呼气气流受限，而在收缩时则不会，并且UAM的呼气收缩在口腔处施加负压期间稳定上气道。
