Electroencephalogram Studies of Induction and Recovery From Ketamine-Induced General Anesthesia
Phase: PHASE2
Conditions: Anesthesia
Sponsor: Massachusetts General Hospital

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Electroencephalogram Studies of Induction and Recovery from Ketamine-Induced General Anesthesia  
 
NCT 03553758 
5/11/2018 

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Electroencephalogram Studies of Induction and Recovery from Ketamine-Induced General Anesthesia 
 
Principal Investigator: Oluwaseun Johnson-Akeju, M.D., M.M.Sc 
 
1. BACKGROUND AND SIGNIFICANCE 
General anesthesia is a man-made, neurophysiological phenomenon that has been developed 
empirically to enable the safe and humane performance of surgical and non-surgical procedures. The state 
consists of unconsciousness, amnesia, analgesia, and immobility along with maintenance of physiological 
stability.1 Although general anesthesia is a neurophysiological phenomenon, until recently, approaches to 
studying the mechanisms of anesthetic action have focused primarily on characterizing the actions of these 
agents at molecular targets in the brain and spinal cord.2-5 This important work has identified common 
molecular and pharmacological principles of anesthetics and has established that there are several rather than 
a single mechanism of anesthetic action.6,7 Characterization of pharmacokinetic and pharmacodynamic 
properties, another focus of anesthesia drug research, has provided the guidelines for anesthetic drug dosing.8 
A considerable gap lies between knowing the multiple targets to which anesthetics bind, their pharmacological 
properties, and stating how actions at these targets lead to any behavioral state of general anesthesia. This is 
a problem in systems neuroscience as it requires defining how the stimulus (the anesthetic) acts in specific 
neural circuits to produce one or more behavioral states (unconsciousness, amnesia, analgesia, immobility).9 
 
Human Studies of Anesthesia 
In recent years, aided largely by non-invasive imaging methods, significant progress has been made in 
understanding systems-level anesthetic effects in humans. General anesthetic drugs dramatically reduce or 
increase (unique to ketamine) cerebral metabolism and blood flow globally across the brain.10-16 This is 
consistent with our understanding that general anesthetic drugs act at multiple sites throughout the brain.1,9 
Stimulus-induced activity in primary cortical areas decreases under anesthesia,16-20 as does functional 
connectivity,21-26 though some degree of resting state connectivity has been shown to persist.27,28 Ascending 
arousal systems spanning the brainstem, thalamic and cortical networks appear to become active during 
emergence from anesthesia-induced unconsciousness.29,30 Disruption of anterior-posterior cortico-cortical 
connectivity has been proposed as a common mechanism to explain these diverse findings.31-36 However, 
there is also considerable evidence to support thalamocortical12,20,26,30,37-39 and subcortical mechanisms as 
well.9  
 
The neurophysiological mechanisms underlying these observed changes in brain metabolism and 
functional connectivity remain unclear. However, anesthetic drugs are known to produce large stereotyped 
oscillations that may explain these brain metabolism and functional connectivity changes.30,38-44 To bridge the 
gap between observed changes in brain metabolism and fMRI-derived functional connectivity, it is essential to 
conduct studies that can simultaneously observe fast time-scale neurophysiological dynamics across multiple 
functionally-connected brain regions. To understand how neurophysiology relates to time-varying states of 
altered arousal requires detailed behavioral characterizations. Although it is clear that unresponsiveness is not 
necessarily unconsciousness,45 behavioral responses nonetheless provide crucial information on the state of 
altered arousal.46,47 Most of the aforementioned work has been performed in propofol or inhaled anesthetics, 
and  studies of ketamine are clearly needed. 
 
 
 
 
Ketamine 
Ketamine is an anesthetic, an anesthetic adjunct and an analgesic that acts primarily by binding to 
NMDA type glutamate receptors in the brain and spinal cord.9 Ketamine is a channel blocker and thus requires 
an open channel to be effective.48 Because the channels on inhibitory interneurons are generally more active 
than those on pyramidal neurons, ketamine primarily affects inhibitory interneurons at low to moderate doses 
(Fig. 1), leading typically to increased neural activity.49,50 This is why cerebral metabolism increases with low 
doses of ketamine. Hallucinations, dissociative states, euphoria and dysphoria are common with low dose 
ketamine because brain regions, such as the cortex, hippocampus and amygdala, continue to communicate 

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but with less modulation and control by inhibitory interneurons. Information is processed without proper 
coordination in space and time.1,9 This state is associated with high frequency beta-gamma (>30 Hz) 
oscillations.51 Analgesia results most likely from the action of ketamine on glutamate NMDA receptors at the 
dorsal root ganglia, the first synapse of the pain pathway in the spinal cord where glutamate is the primary 
neurotransmitter (Fig. 1).48  
 
We analyzed 4-channel frontal EEG recorded during routine monitoring in patients receiving ketamine 
(2mg/kg; n = 12 patients) to induce general anesthesia for surgery. As illustrated in figure 2 (middle panel), 
immediately after induction, we observed an alternating pattern of slow oscillations (0.1-4 Hz) and gamma 
bursts (30-40 Hz), Also illustrated in figure 2 (right most panel), this oscillatory dynamic eventually transitioned 
to persistent gamma oscillations (30-40 Hz) after several minutes. Both the slow-gamma and gamma patterns 
were associated with increased theta oscillations (4-8 Hz) and decreased beta/gamma oscillations (10-20 Hz).  
 
Unfortunately, this study and those from other research groups have not provided information on how 
the spatio-temporal dynamics of ketamine-induced oscillatory dynamics relate to loss of consciousness, return 
of consciousness or hallucinatory states. This is because ketamine has been administered in a bolus fashion in 
these studies. Ketamine-induced EEG dynamics may aid principled approaches to brain state monitoring and 
targeting during general anesthesia. They may also lend insights into anti-nociceptive or pain mechanisms. 
Additionally, parallels between ketamine-induced hallucinatory states and clinical diagnoses associated with 
hallucinatory states (i.e. schizophrenia) may lend mechanistic insights into abnormal brain functioning. 
 
Therefore, we aim to study the association between ketamine-induced neural oscillations, altered states 
of arousal and the perception of painful stimuli. Our central hypothesis is that ketamine-induced neural 
oscillations will exhibit clear distinctions between altered arousal states. Our study cohort will be comprised of 
healthy volunteers. We will perform assessments for hallucinations, anxiety and pain. At the conclusion of this 
study, we will have expanded our knowledge of the neurophysiology associated with ketamine-induced altered 
arousal states. The proposed human study is an integral component of our NIH P01 grant “Integrated Systems 
Neuroscience Studies of General Anesthesia (5 P01 GM118269) that is structured to study ketamine-induced 
neurophysiological dynamics across scales using recordings obtained from rodents and non-human primates, 
and from computational models derived from dynamical systems modeling. 
 
2. SPECIFIC AIMS 
AIM 1: To use high-density EEG recordings to characterize the different brain states induced by ketamine  
Hypothesis 1.1. Ketamine gamma-burst pattern will be associated with a zero probability of response to 
auditory stimuli  
Hypothesis 1.2.  Ketamine gamma-stable pattern consists of two distinct brain states: an anesthetic state with 
zero probability of response to auditory stimuli and a hallucinatory state with non-zero probability of response 
to auditory stimuli  
 
AIM 2: To use high-density EEG recordings to characterize oscillatory dynamics associated with the analgesic 
effect of ketamine 
Hypothesis 2.1. Ketamine theta power will correlate with analgesia 
Hypothesis 2.2.  Ketamine gamma power will not correlate with analgesia 
 
AIM 3: To use inflammatory profiling of serum to understand the effect of ketamine on systemic inflammation  
Hypothesis 3.1.  Ketamine-anesthesia will be associated with decreased levels of pro-inflammatory cytokines 
interleukin 6 and TNF-alpha 
Hypothesis 3.2.  Levels of pro-inflammatory cytokines interleukin 6 and TNF-alpha will correlate with a 
decrease in perception of painful stimuli 
 
3. SUBJECT SELECTION  
All study subjects will be American Society of Anesthesiologists (ASA) physical status classification P1. That is, 
all study subjects will be fit and healthy. A complete medical history will be taken and a complete physical 
examination will be given to rule out active and chronic medical problems.  

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Primary Inclusion Criteria: 
Between the ages of 18 to 45 
Normal body weight and habitus, BMI ≤ 30 
Non-smoker 
American Society of Anesthesiologists (ASA) physical status classification P1 
 
Primary Exclusion Criteria include but are not limited to: 
Cardiovascular: 
myocardial infarction, coronary artery disease, peripheral vascular disease, arrhythmia, 
congestive heart failure, valvular disease, hypertension 
Respiratory:  
bronchitis, chronic obstructive pulmonary disease, smoking, shortness of breath 
Hepatic: 
hepatitis, jaundice, ascites 
Neurologic: 
seizure, stroke, positive neurologic findings on neurologic examination, multiple 
sclerosis, Meniere’s disease, Parkinson’s disease, neuropathy, peripheral stenosis 
Gastrointestinal: 
esophageal reflux, hiatal hernia, ulcer 
Endocrine: 
diabetes, thyroid disease 
Renal: 
acute or chronic severe renal insufficiency  
Hematologic: 
blood dyscrasias, anemia, coagulopathies, on anticoagulant therapy 
Musculoskeletal: 
prior surgery or trauma to head neck or face, arthritis, personal or family history of 
malignant hyperthermia 
Psychiatric: 
history or treatment for an active psychiatric problem, depression 
Reproductive: 
pregnancy, breast-feeding 
Medications:  
regular use of prescription and non-prescription medications expected to affect CNS 
function, St. John’s Wort 
Allergies:  
labetalol, ondansetron, glycopyrrolate, ketamine, midazolam 
 
Patients will be excluded from our study if they fail to pass a drug test that screens for the following: 
Cocaine 
(COC), 
d-Amphetamine 
(AMP), 
d-Methamphetamine 
(Mamp), 
Tetrahydrocannabinol (THC), Methadone (MTD), Opiates (OPI), Phencyclidine 
(PCP), Barbiturates (BAR), Benzodiazepines (BZO), Oxycodone (OXY) 
 
 
Recruitment:  We will select 15 volunteer subjects (male and female) between the ages of 18-45 years.  
The subjects will be recruited using:                                                 
An announcement of the study distributed through the Partners Public Affairs distribution list.                 
The MGH Research Study Volunteer Program (RSVP).       
 
 
 
4. SUBJECT ENROLLMENT 
Procedure for informed consent: Prior to the study, each subject will sign informed consent (detailed in 
Screening Visit subsection of Study Design Section below). The investigator obtaining consent will explain in 
detail the protocol of the study, its purpose and potential benefits to society. Subjects will be informed that if 
they feel uncomfortable with the study, they can choose to terminate the study at any time.  
 
Treatment Assignment and Randomization: Not applicable 
                              
Retention: All subjects who provide verbal or written consent but later decline participation in the study will not 
be subject to any study-related follow-up. 
 
Remuneration: For successful completion of this protocol, subject remuneration will be $500. The subject will 
also be compensated for the cost of parking for their study visit. 
 

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Location:  These studies will take place on White 5 at the Carl Rosow Center for Clinical Research. White 5, 
which is located in the cardiac anesthesia office suite, was constructed specifically for the performance of 
research on human subjects receiving the depressant medications used in anesthesia. The research area is 
built to the same standard as a typical surgical procedure room at MGH with respect to ventilation, temperature 
control, plumbing and electrical facilities, as well as storage. There is piped oxygen and air, wall suction and 
waste anesthetic gas removal. The hospital’s backup generator supports electrical outlets in this location. 
There is a fully equipped anesthesia machine, standard anesthetic care monitors and a fully equipped code 
cart. The code cart and medications are checked at intervals by personnel from the OR pharmacy, and the 
anesthesia equipment is safety checked and maintained by Anesthesia Bioengineering. Research subjects 
receiving anesthetic drugs in this unit are given an identical standard of care as patients in MGH operating 
rooms.  
 
5. STUDY PROCEDURES 
Screening Visit: All subjects will complete a screening visit. Informed consent will be obtained during this 
study visit. Study subjects will undergo screening to ensure that they meet the basic inclusion/exclusion criteria 
for the study and give written informed consent. Study staff members will also ensure patients are enrolled in 
an appropriate insurance plan. Insurance coverage will be evaluated through medical record review. Each 
study subject will be asked to bring a copy of his/her insurance card to the screening visit. This is to ensure 
coverage in the unlikely event that follow-up medical care is necessary for an adverse event. All further 
questions will be explained as needed. A urine hCG pregnancy test and urine drug screen will be performed. 
Only subjects with negative tests will be enrolled. 
  
Subjects will be given a standard pre-anesthetic physical examination. Particular attention will be paid to the 
subject’s airway anatomy and neurologic function. Abnormal findings on physical examination may result in 
exclusion from the study. Abnormal findings will be reported to the subjects, and recommendations for medical 
follow-up will be given as needed. 
 
A complete blood count, blood glucose level, liver function tests (LFTs), blood urea nitrogen (BUN) and 
creatinine (Cr) level panel will be obtained at the initial screening visit. For inclusion into the study protocol, 
each subject will be required to have values within the range of normal with the following exceptions: (1) AST 
and ALT levels within 1.5 times the upper limit of normal; (2) Alkaline phosphatase ≤ 130; (3) WBC ≥ 3.5; (4) 
Platelet count ≥ 120; (5) BUN within 1.5 times the upper limit of normal; (6) red cell indices. A formal exception 
will be obtained from the IRB for values outside of this range that represent an expected variation (i.e. 
increased bilirubin in a patient with known Gilbert’s syndrome). Any subject who tests positive for any “street 
drugs” (amphetamine, barbiturates, benzodiazepines, cocaine, opiates, or phencyclidine) will be excluded from 
the study. Any subject who tests positive for cannabinoids may be excluded from the study if drug-abuse is 
suspected. A 12-lead EKG will be performed to confirm healthy cardiac functioning. 
 
Study Visit: During the study, a board-certified anesthesiologist will be present whose sole 
responsibility will be to monitor (check) your safety. The sequence of this study visit will be as follows: 
arrival (approximately 45 minutes), baseline (approximately 15 minutes), loss of consciousness (approximately 
15 minutes), recovery of consciousness (approximately 60 minutes), and discharge (approximately 45 
minutes). We anticipate the study to last approximately 3 to 5 hours.  
 
A. Arrival: Confirmation of the study subjects’ fasting status (minimum 8 hours) will be made. A urine sample 
will be obtained for pregnancy testing in all female study subjects. The following assessments will be 
performed: 1.) Clinician Administered Dissociative States Scale (CADSS)52 to assess for hallucinations; 2.) 
Promis Item Bank v.1.0 – Emotional Distress-Anxiety Short Form 8A modified to ask for symptoms 
experienced within the past hour; 3.) Promis Item Bank v.1.0 – Meaning and purpose Short Form 8A; and, 4.) 
Promis Item Bank v.1.0 – Positive Affect Short Form 15A (modified to ask for symptoms experienced within the 
past hour). The following computer presented neurocognitive assessment tests will also be performed: Global 
Precedence, Operation Span and Columbia Card tasks will also be administered (https://www.neurobs.com). 
 

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Standard monitors for anesthesia care monitoring including blood pressure (cuff), electrocardiogram, 
capnography and pulse oximetry and a 64-channel EEG montage will be placed on the subject. Video of the 
study subject may be recorded during baseline, induction and recovery from hypnosis periods to assess the 
study subject’s level of arousal. Permission to record video for data analysis purposes will be obtained from the 
research consent form. An intravenous line will be placed for drug administration, and we will obtain 
approximately 15ml of blood (baseline pre-ketamine). 
 
During this period, a calibrated cuff pain stimuli will be delivered to the gastrocnemius area of the lower leg 
using a validated cuff pain device (Hokanson Rapid Cuff Inflator),53-56 titrated to 8-9/10 pain. One advantage of 
using cuff algometry pain is that, unlike more superficial methods (e.g. heat pain), cuff pain responses are 
unaffected by sensitization or desensitization of the skin.53  The following questionnaires will be administered to 
assess pain intensity and quality: 1) PROMIS Numeric Rating Scale V1.0 – Pain Intensity 1A; 2) PROMIS 
Scale v2.0 – Neuropathic Pain Quality 5a; and, 3) PROMIS Scale v2.0 – Nociceptive Pain Quality 5a. 
Participants will be oriented to the following pain scale: (1) 0-1 out of 10 as “tolerable”; (2) 2-3 out of 10 as 
“slight discomfort”; (3) 4-7 out of 10 as “moderate discomfort”; (4) 8-9 out of 10 as “painful”; and (5) 10 as 
“maximum pain”. 
 
B. Baseline: A 10 to 15-minute period of EEG recording will be obtained for EEG calibration (i.e. eye 
movements, eye blinks, facial muscle movement) and EEG normalization (awake-eyes closed). Recordings of 
physiological measurements (blood pressure, heart rate, pulse oximetry, end-tidal carbon dioxide, 
electrooculogram, electromyogram and galvanic skin response) will be initiated and maintained from the 
beginning of the study protocol until the subject is ready for discharge.  
 
C. Loss consciousness: 2mg/kg of ketamine will be infused (Medfusion pump) over approximately 5 minutes 
to gradually induce and allow for rapid emergence from ketamine-anesthesia. This anesthetic dose is expected 
to cause approximately 10-15 minutes of loss of consciousness/responsiveness. Subjects will be asked to 
respond to auditory stimuli via button-press jittered at random between 4 and 8 second intervals in order to 
resolve the precise period at which loss and recovery of consciousness/responsiveness occurred at a fine 
temporal scale.  
 
General anesthetic agents, including ketamine, can produce apnea after loss of consciousness. The standard 
clinical approach for airway management in surgical patients is for the anesthesiologist to assist oxygenation 
and ventilation after the loss of consciousness. Thus, a staff anesthesiologist will use standard airway 
maneuvers to maintain normal oxygenation and ventilation. These maneuvers include a jaw and chin thrust 
and assisted ventilation with a mask and bag as part of a circle circuit. Ventilation will be manually assisted as 
needed. At all times, the inspired oxygen concentration, expired carbon dioxide waveform and partial pressure 
will be monitored continuously. The minimum inspired oxygen concentration will be 30%. The end-tidal 
(capnogram) carbon dioxide levels will be maintained within 10% of the baseline values. Manually assisted 
oxygenation and ventilation will continue until the subject recovers spontaneous ventilation. Vlisides et al. 
recently studied correlates of ketamine-anesthesia.57 Because the authors rapidly administered 1.5mg/kg bolus 
of ketamine, the temporal correlation of EEG dynamics with loss of consciousness was not feasible in this 
study. Also, this study did not relate ketamine-induced altered arousal states to pain perception. While planning 
the present study, we spoke with the study authors and confirmed that spontaneous ventilation was maintained 
in all of their study subjects. They noted that nausea was frequently encountered in their study cohort. Thus, 
we expect that spontaneous ventilation will be maintained in our study subjects. Prior to the administration of 
ketamine, we will administer 4mg intravenous odansetron for the pre-emptive treatment of nausea.  
 
Research staff will be responsible for monitoring potential side effects. An experienced board-certified 
anesthesiologist will always monitor and care for the subject according to the standards for delivery of 
anesthesia at MGH. The White 5 research unit is equipped with an anesthesia machine and physiologic data 
are collected electronically. This research unit has been specifically designed and equipped according to MGH 
standards and Massachusetts regulations as an anesthetizing location, and it has been approved for this 
purpose by the Clinical Practices and Safety Committee of the MGH Department of Anesthesia, Critical Care 
and Pain Medicine. Because ketamine may cause an increase in the heart rate and blood pressure, an 

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anesthesiologist may be required to administer intravenous labetalol 5 to 20 mg IV push over approximately 2 
minutes for three blood pressure readings greater than 160/100. Blood pressure readings will be obtained 3-5 
minutes apart. Intravenous glycopyrrolate in 0.1mg increments may also be administered for excessive salivary 
secretion. In order to minimize external stimuli, ketamine administration will occur in a room with low lighting 
and minimal noise. Based on the acuity of physiological or behavioral changes, the anesthesiologist may 
modify these treatment recommendations.  
 
The study investigator will be available over the phone at anytime to address any concerns. Subjects will be 
advised to contact the study PI for any medical related concerns. The study PI may advise subjects to obtain 
follow-up care from their nearest emergency department or primary care physician. Study staff will use the 
EPIC alert system to monitor subject admittance to any Partners Hospital. The study investigator will contact all 
study subjects 24 hours after completion of the study visit to address any concerns or study related adverse 
effects.  
 
D. Recovery of consciousness: We will conduct assessments 5-minutes after recovery of consciousness 
and at approximately 15-minute intervals after recovery of consciousness for a total of three assessments. 
These assessments will consist of: 1.) CADSS; 2.) Promis Item Bank v.1.0 – Emotional Distress-Anxiety Short 
Form 8A modified to ask for symptoms experienced within the past hour; 3.) Promis Item Bank v.1.0 – Meaning 
and Purpose Short Form 8A; and, 4.) Promis Item Bank v.1.0 – Positive Affect Short Form 15A (modified to 
ask for symptoms experienced within the past hour. After these assessments, the cuff pain device will be 
inflated (pre-calibrated pressure; see Arrival subsection above), and pain intensity and quality assessments will 
consist of: 1.) PROMIS Numeric Rating Scale V1.0 – Pain Intensity 1A; 2.) PROMIS Scale v2.0 – Neuropathic 
Pain Quality 5a; and, 3.) PROMIS Scale v2.0 – Nociceptive Pain Quality 5a.  
 
 
After the third assessment (i.e. approximately 35 minutes after recovery of consciousness), we will administer 
0.05 mg/kg of midazolam (maximum dose of 4 mg) to resolve ketamine-induced perceptual disturbances. 
Midazolam is routinely administered during the peri-operative period to mitigate ketamine-induced perceptual 
disturbances. Approximately 5 minutes after midazolam is administered, we will resume assessments for a 
minimum of two assessments (approximately 55 minutes after recovery of consciousness) or until the subject 
is ready for discharge.  We will obtain approximately 15ml of blood (post-ketamine, pre-midazolam). The 
following computer presented neurocognitive assessment tests will also be performed: Global Precedence, 
Operation Span and Columbia Card tasks will also be administered (post-ketamine, pre-midazolam). 
 
 
E. Discharge: If medically stable, as deemed by a board-certified anesthesiologist, the intravenous line and 
physiological monitoring devices will be discontinued, and subjects will be discharged home with a responsible 
family member or other adult caretaker. Discharge home will be based on criteria established by the MGH 
Department of Anesthesia practices for discharge from the hospital following ambulatory surgery. The subject 
must have stable vital signs, be able to respond appropriately to normal commands, be pain free, be free from 
any nausea and vomiting and have no bleeding from the intravenous sites. Subjects must be able to walk 
unassisted and have an accompanying adult to escort them home. Subjects will be advised against returning 
to work and driving or operating heavy equipment for 24 hours.  
 
If subjects experience adverse events at home, they will be referred for evaluation at the nearest emergency 
department. These instructions will also be provided to the responsible adult escort prior to discharge. The 
subject’s individual insurance plan will be responsible for covering this visit.  
 
 
 
6. BIOSTATISTICAL ANALYSIS 
EEG acquisition Preprocessing: Continuous 64-channel EEG will be recorded. All data will be stored for 
subsequent off-line analysis. We will apply an anti-aliasing filter and down-sample the EEG data to reduce 
computational complexity before analysis. Bandpass filtering of the acquired signal will vary depending upon 

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the features of the EEG data of interest. Trigger signals will be sent from the stimulus delivery system to the 
EEG recording system to tag the stimulus events for subsequent binning, temporal epoching and averaging of 
EEG data into the relevant evoked potential averages.  
 
Spectral Analysis: We will compute spectrograms for all subjects using the multitaper method. We will also 
compute group-level baseline-normalized spectrograms for induction and emergence by taking the median 
across subjects with the data aligned to the LOC and ROC time points, respectively. To assess statistical 
significance for the difference in EEG spectra at each frequency, we will compute the 99% confidence interval 
of the median difference between groups by using an empirical bootstrap approach. The null hypothesis will be 
rejected only if the confidence interval of the median difference at each frequency exceeds the significance 
threshold over a contiguous frequency range ≥ 2W. 
 
Eigenvalue and Modal Projection Analyses: We will perform an eigenvector decomposition analysis of the 
cross-spectral matrix to identify the principal modes of oscillation in the conscious and unconscious states and 
to analyze how activity within these principal modes changes through time. We will estimate the cross-spectral 
matrices Pbaseline(f) and Punconscious(f) at each frequency f using the multitaper method using data from the full 
baseline period, as well as segments of at least 5 min extending from LOC to ROC, respectively, for each 
subject. An eigenvalue decomposition of the median cross-spectral matrix at each frequency will be performed. 
Each eigenvector describes a coherent spatial distribution or mode of oscillation, and the corresponding 
eigenvalue quantifies the power in this mode. We then use modal projection analysis to characterize how 
power within principal modes change as a function of time. A permutation-based procedure will be performed 
to assess statistical significance for the modal projection analysis.  
 
Behavioral Analysis: The probability of response to verbal stimuli and the difference in probability of response 
will be estimated by using Bayesian Monte Carlo methods to fit a state-space model to these data. To perform 
group-level analyses, we will align the behavioral data across subjects with respect to each subject’s LOC time 
for induction and with respect to each subject’s ROC time for emergence. We will then pool the responses, and 
pooled data will be used to estimate group-level probabilities of response using the state-space model. 
 
Inflammatory profile Analysis: Plasma samples will be submitted to Myriad/Rules Based Medicine (Myriad 
RBM, Austin, TX, USA) for analysis using their proprietary platform. Wilcoxon rank-sum tests with corrections 
for multiple comparisons will be used to assess analyte differences. In exploratory analyses, we will examine 
Pearson correlations between analytes and variables of interest (i.e. pain, anxiety).  
 
Power Analysis: Assuming the point estimate for gamma power at baseline is -20 dB and 5 dB for ketamine 
induced-unconsciousness (Fig 2.), a standard deviation of 20 dB, type 1 error of 0.05, and desired power of 
0.9, n =14 study volunteers will enable us to detect a gamma power ratio of 25 dB. Therefore, we aim to recruit 
up to 15 subjects.   
 
7. RISKS AND DISCOMFORTS 
EEG risks: The risks associated with EEG electrodes are redness and irritation at the placement site. 
 
Questionnaire risks: Minimal risks associated with completing questionnaires are subject fatigue and the 
possibility of minor psychological distress associated with answering sensitive questions regarding 
psychological functioning. 
 
Data risks: Procedures are in place to reduce the likelihood of a breach of confidentiality including the de-
identification of data and storage of data only on Partners approved devices/portals. However, there is a small 
risk that people outside of this study may be exposed to information about study subjects. 
 
Ketamine: Although it has a good safety profile overall, ketamine has documented sympathomimetic activity 
that may result in mild to moderate increases in heart rate, blood pressure and cardiac output, though this 
activity is generally short-lived.58 Other possible side effects reported during ketamine infusion include 
arrhythmia, increased salivation, increased bronchial secretions, horizontal nystagmus, euphoria and 

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hallucinations. Nystagmus may persist for a period after the ketamine infusion has terminated. Any acute 
changes in physiology, such as changes in heart rate or blood pressure, will be treated using standard 
anesthesiology practices. Rare side effects are allergic reactions (skin rash), pain at the site of injection, 
increased intraocular pressure, ulcerations and inflammation in the bladder (reported in ketamine abusers). 
Ketamine is a controlled substance and has the potential for abuse and dependence, particularly in subjects 
with history of drug abuse. Subjects with history of substance abuse or dependence will be excluded.  
 
Glycopyrrolate risks: Risks involved in the administration of glycopyrrolate include hypertension and 
tachyycardia. 
 
Labetalol risks: Risks involved in the administration of labetalol include hypotension and bradycardia. 
 
Cuff pain stimuli risks: Risks of cuff pain include mild transient bruising associated with inflation of the cuff. 
Our previous experience has also demonstrated that pain ratings go down to nil within several seconds of 
stimulus termination. A button press rapidly deflates the cuff, ensuring subject safety. 
 
Blood draw risks: Pain at the needle insertion site, infection, and bleeding. 
 
 
8. POTENTIAL BENEFITS 
Subjects will have no direct benefit from taking part in this study. Ketamine-induced EEG dynamics may aid 
principled approaches to brain state monitoring and targeting during general anesthesia. They may also lend 
insights into anti-nociceptive or pain mechanisms. 
 
9. MONITORING AND QUALITY ASSURANCE 
The principal investigator and co-investigators will be responsible for monitoring and quality assurance of the 
study. In conjunction with the research assistants, weekly meetings will be held and documented. Current 
subjects in the study will be discussed at each meeting, and charts will be reviewed for completeness. The 
team will evaluate the progress of the study; verify that the rights and well being of the subjects are protected; 
ensure that the reported study data are accurate, complete and verifiable from source documents; and assure 
the conduct of the study is in compliance with the approved protocol and amendments. 
 
Serious Adverse Events:  Expedited review will occur for all events meeting the FDA definition of SAEs – i.e., 
any events that are fatal, immediately life-threatening, permanently or substantially disabling, or 
requiring/prolonging inpatient hospitalization. This also includes any event that a study investigator judges to 
impose a significant hazard, contraindication, side effect or precaution.  Reporting to the IRB will be done 
within 24 hours of the SAE. 
 
Study Stopping Rules:  If at any time during the course of the study the PIs or CO-Is judge that risk to 
subjects outweighs the potential benefits, the PI/CO-Is shall have the discretion and responsibility to 
recommend that the study  terminated.  
  
AE Reporting Guidelines: Unanticipated problems involving risks to subjects or others including adverse 
events will be reported to the PHRC in accordance with PHRC unanticipated problems including adverse 
events reporting guidelines, as well as the RDRC within 5 days. 
 
 

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