Contribution of the Intensive Care Unit Environment to Sleep Disruption in Mechanically Ventilated Patients and Healthy Subjects

Abstract

Recent studies have challenged the traditional hypothesis that excessive environmental noise is central to the etiology of sleep disruption in the intensive care unit (ICU). We characterized potentially disruptive ICU noise stimuli and patient-care activities and determined their relative contributions to sleep disruption. Furthermore, we studied the effect of noise in isolation by placing healthy subjects in the ICU in both normal and noise-reduced locations. Seven mechanically ventilated patients and six healthy subjects were studied by continuous 24-hour polysomnography with time-synchronized environmental monitoring. Sound elevations occurred 36.5 +/- 20.1 times per hour of sleep and were responsible for 20.9 +/- 11.3% of total arousals and awakenings. Patient-care activities occurred 7.8 +/- 4.2 times per hour of sleep and were responsible for 7.1 +/- 4.4% of total arousals and awakenings. Healthy subjects slept relatively well in the typically loud ICU environment and experienced a quantitative, but not qualitative, improvement in sleep in a noise-reduced, single-patient ICU room. Our data indicate that noise and patient-care activities account for less than 30% of arousals and awakenings and suggest that other elements of the critically ill patient's environment or treatment should be investigated in the pathogenesis of ICU sleep disruption.

Nonpharmacological Interventions to Manage Common Symptoms in Patients Receiving Mechanical Ventilation

“…Although the effect of noise may not be directly linked to physiological healing in adults, elevated noise levels do increase stress, which can affect the body's ability to heal. 10,16 Evidence 17 indicates health care environments are getting noisier, and the ICU can be among the noisiest units with its alarms from multiple devices and the sheer number of providers in attendance 24 hours a day. Consider the ICU environment: telephones ringing; alarms from intravenous pumps, monitors, ventilators, and other medical devices; beeps and clicking from computer use; television noise.…”

“…18,20 Approximately half of the sleep that critically ill patients do get occurs during the day rather than primarily at night. 16,21,22 Even when patients appear to be getting an adequate amount of sleep, the quality of the sleep is less optimal than in healthy volunteers. 18,21,23 Compared with healthy volunteers, critically ill patients tend to spend more time in the first 2 stages of sleep, which is more superficial sleep, than in the restorative sleep of the rapid eye movement stage.…”

“…According to estimates, less than 30% of patient awakenings are attributable to noise and care activities, 16 and investigators have surmised that other causes of sleep deprivation or interruption are less obvious and controllable. Increased use of medications such as sedatives, hypnotics, and analgesics in patients receiving mechanical ventilation may actually lead to decreased quality of sleep, a finding that may be counterintuitive.…”

“…18,22,27 Other medications, stress, anxiety, altered circadian rhythms, and altered melatonin secretion may also affect sleep. 16,22 In addition, among patients receiving mechanical ventilation, difficulty in resolving ventilator dyssynchrony may be an important cause of inability to sleep. 16,22,28 Several CATs might be useful in promoting sleep in patients receiving mechanical ventilation.…”

“…16,22 In addition, among patients receiving mechanical ventilation, difficulty in resolving ventilator dyssynchrony may be an important cause of inability to sleep. 16,22,28 Several CATs might be useful in promoting sleep in patients receiving mechanical ventilation. Relaxation techniques such as progressive muscle relaxation can help patients relax successive muscle groups.…”