Wulbrand Henning, McNamara Frances, Thach Bradley T
Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St. Louis, MO 63110, USA.
Sleep. 2008 Jun;31(6):833-40. doi: 10.1093/sleep/31.6.833.
During obstructive sleep apnea (OSA) in adults upper airway reopening coincides with a sudden burst in activity of pharyngeal dilating muscles. This has been attributed to arousal from sleep as indicated by increased EEG activity. Recovery from OSA in infants often occurs in the absence of cortical arousal. To investigate mechanisms involved in recovery, we performed experimental airway occlusions in sleeping infants. Based on past work, our hypothesis was that a sleep startle combined with an augmented breath and heart rate acceleration would occur during the occlusion, and that such brainstem mediated reflexes might provide an explanation for recovery from OSA in the absence of cortical arousal. However, this is contrary to expectations, since lung inflation is believed to be necessary for occurrence of an augmented breath. We studied 16 healthy infants during sleep. We recorded EEG, EOG, ECG, oxygen saturation, diaphragmatic, nuchal and limb electromyograms, face mask pressure, and airflow. A startle, accompanied by neck extension, limb and nuchal EMG activation, as well as heart rate acceleration occurred during all airway occlusions. The startle occurred simultaneously with a large biphasic inspiratory effort, having characteristics of an augmented breath (sigh). In more than a third of cases, this occurred without any evidence of cortical arousal activity. The magnitude of startles as well as the increase in heart rate correlated positively with peak airway negative pressure, indicating that arousal processes are graded in intensity. We conclude that the neck extension and pharyngeal dilating muscle activity associated with the startle and augmented breath may account for recovery of airway patency in infants as they do adults. Lung inflation is not a prerequisite for the reflex to occur.
在成人阻塞性睡眠呼吸暂停（OSA）期间，上气道重新开放与咽部扩张肌活动的突然爆发同时发生。这被归因于脑电图活动增加所表明的从睡眠中觉醒。婴儿从OSA恢复通常在没有皮质觉醒的情况下发生。为了研究恢复过程中涉及的机制，我们对睡眠中的婴儿进行了实验性气道阻塞。基于过去的研究，我们的假设是在阻塞期间会出现睡眠惊跳，并伴有呼吸增强和心率加速，并且这种脑干介导的反射可能为婴儿在没有皮质觉醒的情况下从OSA恢复提供一种解释。然而，这与预期相反，因为人们认为肺部充气是呼吸增强发生的必要条件。我们在睡眠期间研究了16名健康婴儿。我们记录了脑电图、眼电图、心电图、血氧饱和度、膈肌、颈部和肢体肌电图、面罩压力和气流。在所有气道阻塞期间都出现了惊跳，伴有颈部伸展、肢体和颈部肌电图激活以及心率加速。惊跳与一次大的双相吸气努力同时发生，具有呼吸增强（叹息）的特征。在超过三分之一的病例中，这一情况发生时没有任何皮质觉醒活动的证据。惊跳的幅度以及心率的增加与气道负压峰值呈正相关，表明觉醒过程的强度是分级的。我们得出结论，与惊跳和呼吸增强相关的颈部伸展和咽部扩张肌活动可能像在成人中一样解释婴儿气道通畅的恢复。肺部充气不是该反射发生的先决条件。
