Zhang Zhongxing, Khatami Ramin
Center for Sleep Medicine and Sleep Research, Clinic Barmelweid, Barmelweid, Switzerland.
Department of Neurology, University Hospital Bern, Bern, Switzerland.
Sleep. 2015 Aug 1;38(8):1211-7. doi: 10.5665/sleep.4894.
Current knowledge on hemodynamics in sleep is limited because available techniques do not allow continuous recordings and mainly focus on cerebral blood flow while neglecting other important parameters, such as blood volume (BV) and vasomotor activity.
Observational study.
Continuous measures of hemodynamics over the left forehead and biceps were performed using near-infrared spectroscopy (NIRS) during nocturnal polysomnography in 16 healthy participants in sleep laboratory.
Temporal dynamics and mean values of cerebral and muscular oxygenated hemoglobin (HbO2), deoxygenated hemoglobin (HHb), and BV during different sleep stages were compared. A biphasic change of cerebral BV was observed which contrasted a monotonic increase of muscular BV during non-rapid eye movement sleep. A significant decrement in cerebral HbO2 and BV accompanied by an increase of HHb was recorded at sleep onset (Phase I). Prior to slow wave sleep (SWS) HbO2 and BV turned to increase whereas HHb began to decrease in subsequent Phase II suggested increased brain perfusion during SWS. The cerebral HbO2 slope correlated to BV slope in Phase I and II, but it only correlated to HHb slope in Phase II. The occurrence time of inflection points correlated to SWS latencies.
Initial decrease of brain perfusion with decreased blood volume (BV) and oxygenated hemoglobin (HbO2) together with increasing muscular BV fit thermoregulation process at sleep onset. The uncorrelated and correlated slopes of HbO2 and deoxygenated hemoglobin indicate different mechanisms underlying the biphasic hemodynamic process in light sleep and slow wave sleep (SWS). In SWS, changes in vasomotor activity (i.e., increased vasodilatation) may mediate increasing cerebral and muscular BV.
目前关于睡眠中血流动力学的知识有限，因为现有技术无法进行连续记录，且主要关注脑血流量，而忽略了其他重要参数，如血容量（BV）和血管舒缩活动。
观察性研究。
在睡眠实验室对16名健康参与者进行夜间多导睡眠图检查时，使用近红外光谱（NIRS）对左前额和二头肌的血流动力学进行连续测量。
比较了不同睡眠阶段大脑和肌肉的氧合血红蛋白（HbO2）、脱氧血红蛋白（HHb）和BV的时间动态变化及平均值。观察到大脑BV呈双相变化，这与非快速眼动睡眠期间肌肉BV的单调增加形成对比。在睡眠开始（第一阶段）时，大脑HbO2和BV显著下降，同时HHb增加。在慢波睡眠（SWS）之前，HbO2和BV转而增加，而在随后的第二阶段HHb开始下降，这表明SWS期间脑灌注增加。在第一阶段和第二阶段，大脑HbO2斜率与BV斜率相关，但仅在第二阶段与HHb斜率相关。拐点出现时间与SWS潜伏期相关。
睡眠开始时脑灌注最初下降，血容量（BV）和氧合血红蛋白（HbO2）减少，同时肌肉BV增加，符合体温调节过程。HbO2和脱氧血红蛋白的非相关和相关斜率表明浅睡眠和慢波睡眠（SWS）中双相血流动力学过程的不同机制。在SWS中，血管舒缩活动的变化（即血管扩张增加）可能介导大脑和肌肉BV的增加。
