Mezzanotte W S, Tangel D J, White D P
University of Colorado Health Sciences Center, Denver, Colorado, USA.
Am J Respir Crit Care Med. 1996 Jun;153(6 Pt 1):1880-7. doi: 10.1164/ajrccm.153.6.8665050.
Current evidence suggests that patients with obstructive sleep apnea (OSA) may have augmented pharyngeal dilator muscle activity during wakefulness, to compensate for deficient anatomy. However, the isolated effect of sleep on the activity of these muscles (comparing OSA patients with controls) has not been studied. We therefore determined waking levels of genioglossus (GG) and tensor palatini (TP) muscle activity (% of maximum electromyographic [EMG] activity) in 10 OSA patients and eight controls, and then assessed the impact of the first two breaths of sleep (theta electroencephalographic [EEG] activity) following a period of stable wakefulness. Apnea patients demonstrated greater genioglossal (27.4 +/- 4.0 versus 10.7 +/- 2.1%) and tensor palatini (31.9 +/- 6.5 versus 10.6 +/- 1.9%) EMG activity than did controls during wakefulness. This augmented muscle activity in apnea patients could be reduced to near control levels during wakefulness with the application of continuous positive airway pressure (CPAP) to the upper airway. At sleep onset, control subjects demonstrated small but consistent decrements in the activity of both the TP and GG muscles. On the other hand, apnea patients demonstrated large, significantly greater decrements in TP EMG at sleep onset than did the control subjects. The effect of sleep on GG EMG in apnea patients was inconsistent, with most (n = 7) demonstrating large (significantly larger than controls) decrements in genioglossal activity. However, three OSA patients demonstrated small increments in GG EMG at sleep onset despite falling TP EMG and obstructive apnea or hypopnea. We conclude that sleep onset is associated with significantly larger decrements in TP muscle EMG activity in OSA patients than in controls, which may represent a loss of neuromuscular compensation that is present during wakefulness. However, our results for the GG muscle were more variable, and did not always support this hypothesis.
目前的证据表明，阻塞性睡眠呼吸暂停（OSA）患者在清醒时可能会增强咽部扩张肌的活动，以弥补解剖结构上的缺陷。然而，睡眠对这些肌肉活动的单独影响（比较OSA患者与对照组）尚未得到研究。因此，我们测定了10例OSA患者和8例对照者的颏舌肌（GG）和腭帆张肌（TP）肌肉活动的清醒水平（最大肌电图[EMG]活动的百分比），然后评估了一段稳定清醒期后的前两口气睡眠（theta脑电图[EEG]活动）的影响。与对照组相比，呼吸暂停患者在清醒时颏舌肌（27.4±4.0%对10.7±2.1%）和腭帆张肌（31.9±6.5%对10.6±1.9%）的EMG活动更强。通过对上气道应用持续气道正压通气（CPAP），呼吸暂停患者在清醒时这种增强的肌肉活动可降至接近对照水平。在睡眠开始时，对照组受试者的TP和GG肌肉活动均出现小幅度但持续的下降。另一方面，呼吸暂停患者在睡眠开始时TP EMG的下降幅度比对照组受试者大得多且显著。睡眠对呼吸暂停患者GG EMG的影响不一致，大多数（n = 7）患者的颏舌肌活动出现大幅下降（显著大于对照组）。然而，3例OSA患者在睡眠开始时尽管TP EMG下降且出现阻塞性呼吸暂停或呼吸不足，但GG EMG仍出现小幅增加。我们得出结论，与对照组相比，睡眠开始时OSA患者TP肌肉EMG活动的下降幅度显著更大，这可能代表清醒时存在的神经肌肉补偿的丧失。然而，我们对GG肌肉的研究结果更具变异性，并不总是支持这一假设。
