Clinical trial NCT02624401: The Neural Mechanisms of Anesthesia and Human Consciousness (Part 6)
Official title: The Neural Mechanisms of Anesthesia and Human Consciousness (Part 6)
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: PHASE4
Conditions: Anesthesia
Unconsciousness
Lead sponsor: University of Turku
Sponsor class: OTHER
Collaborators: name: University of California, Irvine
name: University of Michigan
name: Yale University
name: University of Helsinki
First posted: 2015-12-08
Enrollment: 160
Sex: MALE
Minimum age (years): 18
Maximum age (years): 30
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: PARALLEL
Primary purpose: BASIC_SCIENCE

Brief summary: Positron Emission Tomography (PET), Magnetic Resonance Imaging (MRI) and electroencephalography (EEG) studies will be carried out to reveal the neural correlates of consciousness. Consciousness of the subjects will be manipulated with anesthetic agents dexmedetomidine, propofol, S-ketamine and sevoflurane. One-hundred-and-sixty (160) healthy male subjects will be recruited to receive EC50 concentration of the anesthetic (40 dexmedetomidine, 40 propofol, 20 S-ketamine, 40 sevoflurane) or placebo (20) while being imaged for cerebral metabolic rate of glucose (CMRglu). Also genetic, immunological and metabolomics samples will be taken and analysed to find possible genetic factors explaining the variability in drug response and to find chemical fingerprints of acute drug effect.

Detailed description: The explanation of consciousness poses one of the greatest challenges to science and philosophy in the 21st century. It remains unclear what consciousness is and how it emerges from brain activity. Positron Emission Tomography (PET), Magnetic Resonance Imaging (MRI) and electroencephalography (EEG) studies will be carried out to reveal the neural correlates of consciousness. Consciousness of the subjects will be manipulated with anesthetic agents dexmedetomidine acting through α2-agonism, with propofol and sevoflurane both mainly acting through the enhancement of gamma-aminobutyric acid (GABA) system, and with S-ketamine acting through N-methyl-D-aspartate (NMDA) receptor antagonism. One-hundred-and-sixty (160) healthy male subjects will be recruited to receive EC50 concentration of either dexmedetomidine, propofol, S-ketamine or sevoflurane, or placebo while being imaged for cerebral metabolic rate of glucose (CMRglu). 40 subjects will receive dexmedetomidine, 40 subjects propofol, 20 subjects S-ketamine, 40 subjects sevoflurane and 20 subjects will receive placebo. Also genetic, immunological and metabolomics samples will be taken and analysed to find possible genetic factors explaining the variability in drug response and to find possible immunological and chemical fingerprints of acute drug effect.

Eligibility criteria: Inclusion Criteria:

1. Male
2. Age 18-30 years
3. Good general health i.e. American Society of Anesthesiologists (ASA) physical status I
4. Fluent in Finnish language
5. Right handedness
6. Written informed consent
7. Good sleep quality

Exclusion Criteria:

1. Chronic medication
2. History of alcohol and/or drug abuse
3. Strong susceptibility for allergic reactions
4. Serious nausea in connection with previous anesthesia
5. Strong susceptibility for nausea
6. Any use of drugs or alcohol during the 48 hours preceding anesthesia
7. Use of caffeine products 10-12 hours prior the study
8. Smoking
9. Clinically significant previous cardiac arrhythmia / cardiac conduction impairment
10. Clinically significant abnormality in prestudy laboratory tests
11. Positive result in the drug screening test
12. Blood donation within 90 days prior to the study
13. Participation in any medical study with an experimental drug or device during the preceding 60 days
14. The study subject has undergone a prior PET or SPECT study
15. Any contraindication to magnetic resonance imaging (MRI)
16. Hearing impairment
17. Detected unsuitability based on MRI scanning results if available before the PET scanning
18. Sleep disorder or severe sleep problem

Primary outcomes:
measure: Regional cerebral metabolism of glucose
timeFrame: 40 min
Secondary outcomes:
measure: EEG
timeFrame: 1 hour
measure: Immunological effects
timeFrame: 2 hours
measure: Metabolomic effects
timeFrame: 2 hours
measure: Gene expression
timeFrame: 2 hours
measure: Psychological well-being
timeFrame: 2 hours
measure: Dream report
timeFrame: 1 hour
Other outcomes:
measure: Drug concentration in plasma or end-tidal
timeFrame: 1 hour
Locations:
city: Turku
country: Finland
facility: Turku PET Centre
Study officials:
affiliation: Turku PET Centre, University of Turku, Turku, Finland
name: Harry Scheinin, MD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Langsjo JW, Alkire MT, Kaskinoro K, Hayama H, Maksimow A, Kaisti KK, Aalto S, Aantaa R, Jaaskelainen SK, Revonsuo A, Scheinin H. Returning from oblivion: imaging the neural core of consciousness. J Neurosci. 2012 Apr 4;32(14):4935-43. doi: 10.1523/JNEUROSCI.4962-11.2012.
citation: Langsjo JW, Revonsuo A, Scheinin H. Harnessing anesthesia and brain imaging for the study of human consciousness. Curr Pharm Des. 2014;20(26):4211-24.
citation: Nummela AJ, Laaksonen LT, Laitio TT, Kallionpaa RE, Langsjo JW, Scheinin JM, Vahlberg TJ, Koskela HT, Aittomaki V, Valli KJ, Revonsuo A, Niemi M, Perola M, Scheinin H. Effects of dexmedetomidine, propofol, sevoflurane and S-ketamine on the human metabolome: A randomised trial using nuclear magnetic resonance spectroscopy. Eur J Anaesthesiol. 2022 Jun 1;39(6):521-532. doi: 10.1097/EJA.0000000000001591. Epub 2021 Sep 22.
citation: Laaksonen L, Kallioinen M, Langsjo J, Laitio T, Scheinin A, Scheinin J, Kaisti K, Maksimow A, Kallionpaa RE, Rajala V, Johansson J, Kantonen O, Nyman M, Siren S, Valli K, Revonsuo A, Solin O, Vahlberg T, Alkire M, Scheinin H. Comparative effects of dexmedetomidine, propofol, sevoflurane, and S-ketamine on regional cerebral glucose metabolism in humans: a positron emission tomography study. Br J Anaesth. 2018 Jul;121(1):281-290. doi: 10.1016/j.bja.2018.04.008. Epub 2018 May 8.