Sleep and Circadian Rhythms in Mechanically Ventilated Patients

Sleep and Circadian Rhythms in Mechanically Ventilated Patients: a Feasibility and Mechanistic Study.

National Heart, Lung, and Blood Institute (NHLBI), The Brain Research Foundation, University of Chicago

This study examines the feasibility of assessing sleep and circadian rhythmicity in critically ill patients undergoing mechanical ventilation. Secondarily, it will examine the feasibility of reducing subject exposure to environmental light and noise and of delivering routine care according to classical day/night routines.

Over 1 million patients develop respiratory failure annually in the United States; yet, the sleep of patients undergoing mechanical ventilation has received little attention. This protocol enrolls acutely ill medical patients undergoing mechanical ventilation. The feasibility of assessing sleep and circadian rhythmicity through the use of continuous bedside polysomnography and the measurement of core body temperature and urinary hormonal levels at frequent intervals will be explored. As a secondary goal, the feasibility of delivering routine care according to classical day/night routines, and of employing various noise and light reduction strategies at night, will be explored in a subset of subjects.

Subjects were randomized in 1:1 fashion to receive the Environmental Modification protocol or usual care. Subsequently a third, observational arm was opened to acquire more physiologic data.

Subjects assigned to this group receive the environmental modification intervention for 48 hours beginning the morning after enrollment.

Usual care is provided for the first 48 hours. Subsequently, in the initial protocol, subjects received 48 hours of the environmental modification intervention so long as they remained in the ICU during this time. The opportunity to receive the "Delayed" intervention was later removed from the protocol.

Environmental modification consists of nursing-related efforts to optimize daytime light exposure, to minimize nighttime light and noise exposure, and to batch nursing care at night.

Percentage of Subjects Who Successfully Undergo Continuous Bedside Polysomnography for at Least 24 Hours.

This study assesses the feasibility of studying sleep and circadian rhythmicity in acutely ill, mechanically ventilated patients through the application of continuous bedside polysomnography. Feasibility will be assessed by determining the percentage of enrolled subjects who undergo at least 24 hours of continuous bedside polysomnography.

This outcome measure will examine, in a preliminary fashion, subject tolerance of the environmental modification protocol. Tolerance will be assessed through qualitative interviews performed by the PI with the subjects.

The number of participants in each group who exhibit normal timing of 6-sulfatoxymelatonin excretion will be reported. The normal timing of peak melatonin excretion was considered to be between midnight and 05:00. Subjects in whom the melatonin onset occurred after midnight or the acrophase occurred after 05:00 were considered to be phase delayed, while patients whose acrophase occurred prior to midnight were considered to be phase advanced.

Inclusion Criteria: Adults undergoing mechanical ventilation in the medical intensive care unit. Exclusion Criteria: Central nervous system disease (stroke, seizure, dementia, etc) Metabolic or hypoxic encephalopathy Confirmed or suspected drug overdose Currently receiving neuromuscular blockers Coma