REcovery from DEXmedetomidine-Induced Unresponsiveness (REDEX): A Study Protocol for a Single Center, Parallel Arm, Non-Randomized, Controlled Pilot Trial in Healthy Volunteers

David R Schreier,1– 4 Matteo Fecchio,3 Christian S Guay,1,2,5 Reid G Kovacs,1,6– 8 Mark Olchanyi,2,3,6 Ariel L Mueller,1 Timothy T Houle,1 Brian L Edlow,3,9 Emery N Brown,1,2,6,7 Ken Solt1 1Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Department of Anaesthesia, Harvard Medical School, Boston, MA, USA; 2Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA, USA; 3Center for Neurotechnology and Neurorecovery, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA; 4Department of Neurology, Inselspital, Bern University Hospital, and University of Bern, Bern, Switzerland; 5Department of Anesthesiology, Perioperative and Pain Medicine, The University of Utah, Salt Lake City, UT, USA; 6Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, USA; 7Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA; 8Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA; 9Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USACorrespondence: David R Schreier, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, 55 Fruit Street, Boston, MA, 02114, USA, Email [email protected]: Dexmedetomidine (DEX) is a well-tolerated sedative drug that induces a sleep-like state. DEX sedation offers a model to study transitions between different states of consciousness (indicated by, eg, behavior, the electroencephalogram (EEG), or transcranial magnetic stimulation (TMS) evoked EEG responses). However, the effects of repeated DEX exposure on recovery are poorly understood and will be investigated in this pilot study.Participants and Methods: We aim to enroll 12 healthy volunteers (6 females, 6 males). Although we do not expect TMS-EEG to interfere with DEX sedation, due to the paucity of evidence this study uses a parallel arm design (TMS-EEG, non-TMS-EEG). Participants will be sedated twice, one week apart, and responsiveness monitored by a click-task to auditory beeps. A 64-channel EEG and additional physiological signals will be recorded. Cognition and vigilance tests will be performed before sedation (baseline), after return of responsiveness (ROR), and before discharge. TMS-EEG will be performed at baseline, during sedation, and during recovery. Using a smartwatch and questionnaires, we will assess sleep quality, sleepiness, and experiences during sedation and TMS-EEG.Results: We will report the difference of time to ROR between the first and second study visit, and explore potential differences across sex and study arms. We will evaluate state transitions by comparing responsiveness, traditional EEG signatures, TMS-evoked EEG responses (ie, perturbational complexity index), and report on cognition and vigilance test performance.Conclusion: This pilot trial will report on the effect of repeated DEX exposure on the recovery period, and the investigation of state transitions will advance our scientific understanding of altered states of consciousness. REDEX will provide valuable insights and data for designing future DEX sedation studies. Moreover, we will report on the potential of biological sex as a confounding factor and the feasibility of TMS-EEG under DEX.Keywords: consciousness, sedation, sleep, electroencephalography, transcranial magnetic stimulation, target-controlled infusion