Fogel Robert B, Trinder John, Malhotra Atul, Stanchina Michael, Edwards Jill K, Schory Karen E, White David P
Harvard Medical School and Division of Sleep Medicine, Brigham and Women's Hospital, 221 Longwood Avenue, Boston, MA 02115, USA.
J Physiol. 2003 Aug 1;550(Pt 3):899-910. doi: 10.1113/jphysiol.2003.038810. Epub 2003 Jun 13.
Pharyngeal dilator muscles are clearly important in the pathogenesis of obstructive sleep apnoea syndrome. Substantial data support the role of a local negative pressure reflex in modifying genioglossal activation across inspiration during wakefulness. Using a model of passive negative pressure ventilation, we have previously reported a tight relationship between varying intrapharyngeal negative pressures and genioglossal muscle activation (GGEMG) during wakefulness. In this study, we used this model to examine the slope of the relationship between epiglottic pressure (Pepi) and GGEMG, during stable NREM sleep and the transition from wakefulness to sleep. We found that there was a constant relationship between negative epiglottic pressure and GGEMG during both basal breathing (BB) and negative pressure ventilation (NPV) during wakefulness (slope GGEMG/Pepi 1.86+/-0.3 vs. 1.79+/-0.3 arbitrary units (a.u.) cmH2O(-1)). However, while this relationship remained stable during NREM sleep during BB, it was markedly reduced during NPV during sleep (2.27+/-0.4 vs. 0.58+/-0.1 a.u. cmH2O(-1)). This was associated with a markedly higher pharyngeal airflow resistance during sleep during NPV. At the transition from wakefulness to sleep there was also a greater reduction in peak GGEMG seen during NPV than during BB. These data suggest that while the negative pressure reflex is able to maintain GGEMG during passive NPV during wakefulness, this reflex is unable to do so during sleep. The loss of this protective mechanism during sleep suggests that an airway dependent upon such mechanisms (as in the patient with sleep apnoea) will be prone to collapse during sleep.
咽扩张肌在阻塞性睡眠呼吸暂停综合征的发病机制中显然起着重要作用。大量数据支持局部负压反射在清醒状态下吸气过程中调节颏舌肌激活的作用。我们之前使用被动负压通气模型报道了清醒状态下不同咽内负压与颏舌肌肌电图（GGEMG）之间存在紧密关系。在本研究中，我们使用该模型研究了在稳定的非快速眼动睡眠以及从清醒到睡眠的过渡过程中，会厌压力（Pepi）与GGEMG之间关系的斜率。我们发现，在清醒状态下的基础呼吸（BB）和负压通气（NPV）过程中，负会厌压力与GGEMG之间存在恒定关系（GGEMG/Pepi斜率分别为1.86±0.3与1.79±0.3任意单位（a.u.）cmH₂O⁻¹）。然而，虽然这种关系在BB期间的非快速眼动睡眠中保持稳定，但在睡眠期间的NPV过程中却明显降低（2.27±0.4与0.58±0.1 a.u. cmH₂O⁻¹）。这与睡眠期间NPV过程中明显更高的咽气流阻力有关。在从清醒到睡眠的过渡过程中，NPV期间所见的GGEMG峰值降低幅度也比BB期间更大。这些数据表明，虽然负压反射在清醒状态下的被动NPV过程中能够维持GGEMG，但在睡眠期间却无法做到。睡眠期间这种保护机制的丧失表明，依赖于这种机制的气道（如睡眠呼吸暂停患者的气道）在睡眠期间容易塌陷。
