Afifi Lamia, Guilleminault Christian, Colrain Ian M
Department of Neurology, Cairo University, Cairo, Egypt.
Respir Physiol Neurobiol. 2003 Jul 16;136(2-3):221-34. doi: 10.1016/s1569-9048(03)00084-3.
The application of inspiratory occlusion stimuli produces cortical responses called respiratory-related evoked potentials (RREPs). During wakefulness the RREP waveform consists of early P1 and Nf components, an N1 and a P300. During non-REM sleep the predominant component is an N550, best seen in the averages of elicited K-complexes. Obstructive sleep apnea syndrome (OSAS) patients have been previously shown to have a normal wake RREP but to have a reduced amplitude N550 and a smaller proportion of elicited K-complexes than controls. The present study tested the hypothesis that this reflects a sleep-specific dampening peculiar to inspiratory effort-related stimuli, by assessing both respiratory and auditory evoked potentials (AEPs) during wakefulness and non-REM sleep in OSAS patients and controls. Auditory tones were presented in an oddball sequence during wakefulness and as a monotonous series during stage 2 sleep. Inspiratory occlusions, delivered for 500 msec via an nCPAP mask were also presented during wakefulness and stage 2 sleep, every three to five breaths. Data were collected from ten OSAS patients and ten controls. There were no significant differences in the amplitudes of the auditory N1 and P3 or the respiratory P1, Nf, N1 or P3 components during wakefulness. The amplitude of the auditory N550 and the proportion of elicited K-complexes did not differ between groups for auditory stimuli presented during stage 2 sleep. The respiratory N550 and K-complex elicitation rate were both significantly reduced in the OSAS group, despite there being no differences in the mask occlusion pressure response to the occlusion. The results confirm a blunted cortical response to inspiratory occlusions that is specific to sleep. The absence of significant group differences in the responses to auditory stimuli highlight that the sleep-related differences seen in OSAS patients are specific to the processing of inspiratory effort related stimuli.
吸气阻断刺激的应用会产生称为呼吸相关诱发电位（RREPs）的皮质反应。在清醒状态下，RREP波形由早期的P1和Nf成分、一个N1和一个P300组成。在非快速眼动睡眠期间，主要成分是N550，在诱发的K复合波的平均值中最明显。先前已表明，阻塞性睡眠呼吸暂停综合征（OSAS）患者清醒时的RREP正常，但与对照组相比，其N550振幅降低，诱发的K复合波比例较小。本研究通过评估OSAS患者和对照组在清醒和非快速眼动睡眠期间的呼吸和听觉诱发电位（AEPs），检验了这反映了与吸气努力相关刺激特有的睡眠特异性抑制这一假设。在清醒期间，听觉音调以奇偶数序列呈现，在睡眠第2阶段以单调系列呈现。在清醒和睡眠第2阶段，每隔三到五次呼吸，还通过nCPAP面罩进行500毫秒的吸气阻断。从10名OSAS患者和10名对照中收集数据。清醒时，听觉N1和P3或呼吸P1、Nf、N1或P3成分的振幅没有显著差异。在睡眠第2阶段呈现听觉刺激时，两组之间听觉N550的振幅和诱发的K复合波的比例没有差异。尽管面罩阻断压力对阻断的反应没有差异，但OSAS组的呼吸N550和K复合波诱发率均显著降低。结果证实了对吸气阻断的皮质反应减弱是睡眠特有的。对听觉刺激反应中没有显著的组间差异，这突出表明OSAS患者中观察到的与睡眠相关的差异是与吸气努力相关刺激处理特有的。
