Arousal Pathways and Emergence From Sedation

• Status: Unknown status
• Trial end date: 2016-12-01
• Target enrollment: 0
• Participant gender: Male

Summary

Emergence from sedation involves an increase in both the level of consciousness and arousal. Some insight to the neural core of consciousness was gained in the recent past. Our research objective is to characterize for the first time the spatiotemporal mobilization of the ascending reticular activating system during emergence from sedation; stated otherwise - to capture the neural core of arousal.

To achieve this objective we plan to utilize the advanced imaging modality of EEG-fMRI. In short, volunteers will be placed in the MRI. Following baseline recordings they will be sedated with a continuous drip of propofol, titrated to deep sedation. Once in that sedation level, propofol administration will cease until emerging to an awake-calm/light sedation.

Continuous EEG recordings and fMRI scans will be taken, both task specific (auditory oddball) and resting-fMRI. Analyses will focus (but will not be restricted to) on constituents of the ascending reticular activating system.

The expected advances of this proposal are:

1. Emergence from sedation (and anesthesia) is one of the critical stages and least elucidated area in the practice of anesthesia. Delayed awakening of varying degree is not uncommon after anesthesia and may have a number of different causes, individual or combined, which may be both drug or non-drug related, thus causing a diagnostic dilemma. Eventually - better insight into this subject will lead to better clinical practice and better understanding why patients emerge in such a diverse and sometimes unexpected manner.

2. Knowledge of the internal structure underlying arousal from anesthesia will help develop / upgrade brain monitors that could tell the anesthesiologist the patient's level of consciousness and prediction of arousal.

3. A detailed reproducible mapping of the arousal process may serve as the core of a drug screening platform for drugs that may expedite patient arousal.

4. Elucidation of the arousal paradigm from sedation will enhance our knowledge of physiological sleep.

Research hypothesis

Return of consciousness is a complex phenomenon comprising of interplay between the cortex and deeper brain structures. We hypothesize that the activation signature is conserved and similar between subjects. Furthermore, we hypothesize that inter-subject variability will arise mainly in the time domain, as evident from the clinical observation of variable time to emergence in different patients.

• Phase: N/A
• Accepts Healthy Volunteers?: Accepts Healthy Volunteers

Details

• Lead Sponsor: Tel-Aviv Sourasky Medical Center
• Treatments: Propofol

Criteria

Inclusion Criteria:

• Healthy males (ASA scale 1-2), volunteers only

Exclusion Criteria:

• Use of chronic medications or illicit drugs

• Metallic implants

• Previous brain injury

• General anaesthesia up to a week earlier to research examination

• Known drug sensitivity to Propofol, soybean oil or peanuts