The authors of this study sought to determine if sleep regulation as regulated by circadian and homeostatic processes remains organized in patients being mechanically ventilated. The authors discovered that circadian rhythm pacemaker function appears to be “free running” in most patients evaluated.
A comprehensive and well referenced review of sleep and the consequences of sleep deprivation on ICU recovery.
A nice review of the literature pertaining to the use of melatonin in sleep and delirium. The authors concluded that given the limited number of studies and the varied methodology, recommendations regarding the use of melatonin cannot be made at this time.
In this study, the authors evaluated the feasibility of measuring sleep in the ICU using Polysomnography (PSG). Of the 753 patients who were screened, 274 were eligible and 29 were enrolled in the study. Only 2 patients completed 24 hour PSG. The authors cited an unwillingness to undergo PSG, the limited availability of skilled staff, possible discomfort of PSG for patients and frequent turnover during medical ICU admissions as major barriers to using PSG to study sleep disruption in the medical ICU.
195 adult survivors of an ICU admission were enrolled to evaluate factors associated with psychological outcomes up to 6 months after hospital discharge. The authors discovered that female gender, increased stress as well as poor sleep were associated with worse psychological outcomes.
Over a 22-month period, the authors sought to determine sleep quality in patients admitted to the ICU. Compared to home, self reported sleep was significantly worse in the ICU. Poor sleep quality was multi-factorial in nature.
In a randomized crossover physiologic study of a group of 13 critically ill adult patients, the authors sought to determine the effects of propofol while mechanically ventilated in assist mode and sedated to a Ramsey scale of 3. The authors demonstrated that sleep in critically ill patients is disorganized and of poor quality. They also discovered that propofol infusion does not improve sleep, but instead abolishes REM sleep.
In this study of 10 patients, with several limitations including a lack of control group, the authors concluded that mechanically ventilated patients receiving dexmedetomidine showed a shift in sleep to the nighttime with 78% of sleep occurring between 2100– 0600. However, patients in this study did not demonstrate any SWS or REM while sedated with dexmedetomidine.
24 patients with acute hypercapnic respiratory failure were randomly assigned to receive non-invasive ventilation with either a dedicated non-invasive ventilator or a standard ICU ventilator. The standard ICU ventilator group had more arousals because of noise while the dedicated non-invasive ventilator had more arousals secondary to patient ventilator asynchrony. Overall sleep architecture was similar between the two groups. Sleep quality was better with non-invasive ventilation compared to spontaneously breathing.