Quantity and quality of sleep in the surgical intensive care unit: are our patients sleeping?

BACKGROUND

The lack of adequate sleep during intensive care unit (ICU) admission is a frequently overlooked complication. Disrupted sleep is associated with immune system dysfunction, impaired resistance to infection, as well as alterations in nitrogen balance and wound healing. The effects of surgical ICU admission on patients' sleep quality and architecture remain poorly defined. The purpose of this study was to describe the quantity and quality of sleep as well as sleep architecture, as defined by polysomnography (PSG), in patients cared for in the surgical ICU.

METHODS

A prospective observational cohort study was performed at our urban Level I trauma center. A convenience sample of surgical or trauma ICU patients underwent continuous PSG for up to 24 hours to evaluate sleep patterns. A certified sleep technician performed, monitored, and scored all PSG recordings. A single neurologist trained in PSG interpretation reviewed all PSG recordings. chi goodness-of-fit analysis was performed to detect differences in the proportion of time spent in stages 1 and 2 (superficial stages), stages 3 and 4 (deep stages), or rapid eye movement (REM) sleep between study patients and healthy historical controls. All PSG recordings were performed greater than 24 hours after the administration of a general anesthetic. Patients with traumatic brain injury were excluded.

RESULTS

Sixteen patients were selected to undergo PSG recordings. Median age was 37.5 years (range, 20-83), 81.3% were male patients, 62.5% were injured, and 31.3% were mechanically ventilated. Total PSG recording time was 315 hours (mean, 19.7 hours per patient), total sleep time captured by PSG was 132 hours (mean, 8.28 hours per patient), and there were 6.2 awakenings per hour of sleep measured. ICU patients had an increase in the proportion of time spent in the superficial stages of sleep, and a decrease in the proportion of time spent in the deeper stages of sleep as well as a decrease in REM sleep compared with healthy controls (p < 0.001).

CONCLUSIONS

Patients do achieve measurable sleep while cared for in a surgical ICU setting. However, sleep is fragmented and the quality of sleep is markedly abnormal with significant reductions in stages 3 and 4 and REM, the deeper restorative stages of sleep. Further studies on the effects of a strategy to promote sleep during ICU care are warranted.