Mechanism(s) of Anesthesia

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MGH DACC Clinical Practices Committee
An Electroencephalogram Study of Induction and
Recovery from Propofol Anesthesia July 7,
2005 PI Brown CoPI Walsh, Purdon, Mullaly,
Kwo, Harrell, Williams, Dray, Bonmassar,
Angelone, Hamalainen, Barlow, Matten
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Issues for DACC

• Permission to conduct EEG/propofol study
• Identical to DACC-approved EEG/fMRI/propofol
  study, but with EEG only, no fMRI
• Permission to implement protocol at the GCRC
  Bioimaging Core facility (CNY 149) as an offsite
  location

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Overview

• Protocol History
• Research Background
• Walk Through Protocol
• Human Research Protection/ Safety

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Protocol History

• Similar to BIS/propofol protocol by Rosow/Kearse
  (1998)
• Similar to EEG/fMRI/Anesthesia by Brown
• IRB approved (1999-P-010748 MGH)
• Reviewed by MGH DACC CPC
• MGH Mallinckrodt GCRC (GAC)

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EEG/propofol vs. EEG/fMRI/propofol

• EEG only, no fMRI under anesthesia
• Study conducted in standard clinical area
• Airway management with bag-mask
• ASA I Study Subjects ages 18-36
• Conducted in GCRC Bioimaging core
• Meets requirements for off-site anesthesia
• EEG source localization
• Requires structural MRI in separate session

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Research Background
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EEG Source Localization

• Combine structural/conductivity information from
  anatomic MRI to localize auditory,
  somatosensory, and cognitive function
• Faster time scale than fMRI, but spatial
  resolution lower w/ limited subcortical visibility

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Our Objective

• To correlate simultaneous measurements of
• electroencephalogram (EEG)
• plasma levels of propofol
• well-defined behavioral markers
• changes in source localization
• during induction of and recovery from
• general anesthesia.

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Walk Through Protocol

• Study subject pre-anesthesia clinical assessment
• Prior to study
• GCRC White 13
• Induction and Recovery from Propofol
• Study subject follow-up
• Separate anatomic MRI scan (30 minutes)

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Study Protocol Clinical Assessment

• Subject Recruitment
• Healthy male and female volunteers
• Ages 18-36
• Total 44 subjects recruited
• ASA physical status I
• Telephone Questionnaire
• Pre-study Assessment (2 hours)
• History and Physical Examination
• Toxic Screen and Pregnancy Test (female subjects)

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Study Protocol Clinical Preparation

• Toxic screen and pregnancy test
• Standard Anesthesia Monitors
• ECG, BP cuff, pulse oximeter, capnogram
• Additional Monitors
• EEG, arterial line
• Airway Maintenance
• Bag mask
• Phenylephrine to maintain BP
• Additional Drugs
• bicitra, ondansetron

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Study Protocol Overview
DIAGRAM W/ CONCENTRATION PROFILE
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Equipment/ Supplies at CNY 149

• ACLS cart
• Defibrillator
• Anesthesia Cart
• Airway equipment
• Anesthesia Machine
• O2 and Air (Wall and E-cylinders)
• Monitors (FiO2, SaO2, EtCo2, ECG, NIBP, P1)
• Laboratory Testing (urine pregnancy, tox screen,
  ABG)
• iSTAT
• EEG machine and electrodes
• Routinely maintained by Biomedical Engineering

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ACLS Cart, Defibrillator

• PICTUR OF ACLS CART AND DEFIB

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Anesthesia Cart and Anesthesia Machine

• PICTURE OF ANESTHESIA CART AND ANESTHESIA MACHINE

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O2 Supply Wall E-cylinders

• PICTURE OF WALL AIR/02 AND E-CYLINDERS

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Monitors iSTAT
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Nursing Responsibilities

• Page study Physician
• Urine toxicity screen
• Urine pregnancy test
• ART line setup available
• ABG sampling analysis w/ iSTAT
• Preparation of blood samples for storage
  (propofol)

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Medical Staff Responsibilities

• Clinical Anesthesiologist
• care of study subject
• PACU care
• Study Anesthesiologist
• organization and execution of study protocol
• STANPUMP infusion

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Preliminary Studies
MLAEP
EEG Power Spectrum
EEG time series
Propofol
0.0 ug/ml
2.0 ug/ml
4.0 ug/ml