Providing "Good Sleep" for ICU Sedation
Condition: Sleep Disorders
MeSH terms: Sleep Wake Disorders
Study type: Interventional

Summary: 
      Cognitive dysfunction, either alone or as an element in the syndrome of delirium, is a common
      occurrence with an incidence as high as 75% in intensive care unit (ICU) patients and can
      independently result in serious consequences including higher mortality rate. Delirium
      develops through a complex interaction between the patient's baseline vulnerability (risk
      factors) and precipitating factors such as disruption of sleep that may occur during
      hospitalization. While sedative-hypnotic agents that are used to facilitate hypnosis and the
      management of mechanically ventilated patients converge on the neural substrate that mediate
      endogenous sleep, they do so at different juncture points depending on its molecular
      mechanism of hypnotic action. Hypnotic agents that modulate the GABAA receptor converge at
      the level of the hypothalamus while α2 adrenergic agonists converge on sleep pathways within
      the brainstem. This translational project seeks to determine whether sedation mediated by
      activation of α2 adrenoceptors (dexmedetomidine) is more like natural sleep than that
      provided by a sedative agent that modulates the GABAA receptor (propofol). The investigators
      will examine volunteers who will be monitored continuously by electroencephalography (EEG)
      and whole-brain functional connectivity by magnetoencephalography (MEG) during each of three
      sleep stages, namely, that induced by dexmedetomidine, propofol, or saline (natural sleep,
      control). The two drug-induced sleep regimens will be compared to natural sleep using EEG and
      brain connectivity by MEG
    

Detailed description: 
      In this proposal the investigators seek to determine whether sedation mediated by activation
      of α2 adrenoceptors (dexmedetomidine) is more like natural sleep than that provided by a
      sedative agent that modulates the GABAA receptor (propofol), two common widely used sedative
      agents in ICU. Ten volunteers will be enrolled and each subject will be studied on three
      experimental sessions. Subjects will be randomized to receive a continuous infusion of either
      saline, dexmedetomidine (DEX), or propofol in each of the three sessions. By relying on
      clinical rating scales, the investigators ensure that the doses of DEX and propofol
      administered induce equisedative states before progressing to magnetoencephalography and
      electroencephalography data collection.

      If the restorative and reparative benefits of sleep mitigate the development of cognitive
      dysfunction, this will result in shorter ICU length of stay for critically ill patients with
      a concomitant reduction in healthcare costs. Furthermore, it is possible that the restorative
      properties of sleep for the central nervous system can extend to the immune system with less
      infection and/or greater likelihood of survival from sepsis.

      In this manner, our project will translate experimental data towards clinical practice and
      the adoption of rational and clinically supported interventions in the ICU that are likely to
      improve not only patient reported outcome measures, but also the chance of surviving critical
      illness.

      Each experimental session will take a maximum of 7 hours (5 hours maximum for control
      sessions).

      Sessions have to be separated by at least one week. Subjects will be enrolled for a minimum
      of 3 weeks (1 session on each week) and no more than 3 months.
    

Intervention name(s): Normal saline infusion; Dexmedetomidine; Propofol
Intervention type(s): Other; Drug; Drug
Intervention description(s): Normal saline infusion; Infusion of Dexmedetomidine will be administrated during the overnight sleep study. An initial target concentration of 0.25 ng/ml will be selected. After 5 min, the sedative point will be assessed and the concentration will be adjusted stepwise by increments and decrements of 0.05 ng/ml. This process will be repeated until the target sedative state is achieved. Using the Richmond Agitation Sedation Scale (RASS) infusion rates, using known pharmacokinetic parameters will be adjusted to achieve equivalent levels of sedation (RASS -3) for both DEX and propofol sessions.
We aim to achieve an RASS of -3 so that the subjects are "moderately sedated". This state of sedation will be maintained for 3-4 hours.; For propofol, an initial concentration of 0.75 ng/ml will be targeted. Depending on the score achieved, the infusion rate will be increased or decreased every 5 min by 0.2 ng/ml until the target sedative state is achieved.
Note that the target sedative state (RASS score of -3) is the same for both DEX and propofol sessions, with the investigator being unaware of which drug is being administered. To ensure the investigator is not aware of the type of drug being administered, all drug delivery systems will be covered.
Intravenous drug delivery will be continued throughout the scanning period for 3-4 hours to maintain equivalent levels of sedation for both DEX and propofol.
Other intervention name(s): Precedex; DEX; Diprivan
Intervention MeSH terms: Dexmedetomidine; Propofol
Allocation: Randomized
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Other
Keywords: Sleep disruption; Sleep hygiene; Sedative agents and sleep; Electroencephalography; REM sleep; Magnetoencephalography