Division of Pulmonary, Critical Care, and Occupational Medicine, Department of Internal Medicine, University of Iowa, Iowa City, IA, USA.
Sleep. 2012 Aug 1;35(8):1105-14. doi: 10.5665/sleep.1998.
Sleep is regulated by circadian and homeostatic processes and is highly organized temporally. Our study was designed to determine whether this organization is preserved in patients receiving mechanical ventilation (MV) and intravenous sedation.
Observational study.
Academic medical intensive care unit.
Critically ill patients receiving MV and intravenous sedation.
Continuous polysomnography (PSG) was initiated an average of 2.0 (1.0, 3.0) days after ICU admission and continued ≥ 36 h or until the patient was extubated. Sleep staging and power spectral analysis were performed using standard approaches. We also calculated the electroencephalography spectral edge frequency 95% SEF₉₅, a parameter that is normally higher during wakefulness than during sleep. Circadian rhythmicity was assessed in 16 subjects through the measurement of aMT6s in urine samples collected hourly for 24-48 hours. Light intensity at the head of the bed was measured continuously.
We analyzed 819.7 h of PSG recordings from 21 subjects. REM sleep was identified in only 2/21 subjects. Slow wave activity lacked the normal diurnal and ultradian periodicity and homeostatic decline found in healthy adults. In nearly all patients, SEF₉₅ was consistently low without evidence of diurnal rhythmicity (median 6.3 [5.3, 7.8] Hz, n = 18). A circadian rhythm of aMT6s excretion was present in most (13/16, 81.3%) patients, but only 4 subjects had normal timing. Comparison of the SEF₉₅ during the melatonin-based biological night and day revealed no difference between the 2 periods (P = 0.64).
The circadian rhythms and PSG of patients receiving mechanical ventilation and intravenous sedation exhibit pronounced temporal disorganization. The finding that most subjects exhibited preserved, but phase delayed, excretion of aMT6s suggests that the circadian pacemaker of such patients may be free-running.
睡眠受昼夜节律和内稳态过程调节，且具有高度的时间组织性。我们的研究旨在确定在接受机械通气（MV）和静脉镇静的患者中，这种组织是否得到保留。
观察性研究。
学术医疗重症监护病房。
接受 MV 和静脉镇静的重症患者。
连续多导睡眠图（PSG）在 ICU 入院后平均 2.0（1.0，3.0）天开始，并持续≥36 小时或直至患者拔管。使用标准方法进行睡眠分期和功率谱分析。我们还计算了脑电图频谱边缘频率 95% SEF₉₅，该参数在清醒时通常高于睡眠时。通过测量 24-48 小时内每小时采集的尿液样本中的 aMT6s，评估 16 名受试者的昼夜节律性。连续测量床头的光照强度。
我们分析了 21 名受试者的 819.7 小时 PSG 记录。只有 2/21 名受试者出现 REM 睡眠。慢波活动缺乏健康成年人中正常的昼夜和超昼夜周期性和内稳态下降。几乎所有患者的 SEF₉₅均持续较低，没有昼夜节律的证据（中位数 6.3 [5.3，7.8] Hz，n=18）。大多数（13/16，81.3%）患者存在 aMT6s 排泄的昼夜节律，但只有 4 名患者的时间正常。比较基于褪黑素的生物昼夜期间的 SEF₉₅，两个时期之间没有差异（P=0.64）。
接受机械通气和静脉镇静的患者的昼夜节律和 PSG 表现出明显的时间紊乱。大多数患者表现出保留但相位延迟的 aMT6s 排泄表明，此类患者的昼夜节律起搏器可能处于自由运行状态。
