Table Of ContentJ. Schulte am Esch . E. Kochs (Eds.)
Central Nervous System
Monitoring in Anesthesia
and Intensive Care
With 127 Figures, Some in Color
Springer-Verlag
Berlin Heidelberg New York London Paris
Tokyo Hong Kong Barcelona Budapest
Prof. Dr. med. J. SCHULTE AM ESCH
Prof. Dr. med. E. KOCHS
Department of Anesthesiology
University Hospital Eppendorf
University of Hamburg
Martinistrasse 52
20246 Hamburg
Germany
ISBN-13:978-3-642-78443-9 e-ISBN-13 :978-3-642-78441-5
DOl: 10.1007/978-3-642-78441-5
Library of Congress Cataloging-in-Publication Data. Central nervous system monitoring in anesthesia and
intensive care/J. Schulte am Esch, E. Kochs, eds. p. cm, Includes bibliographical references and index. ISBN-
13 :978-3-642-78443-9(U .S.)I.Electroencephalography. 2.Evoked potential (Electrophysiology)3.Patient monitoring.
4. Intraoperative monitoring. 5. Critical care medicine. I. Schulte am Esch, J. (Jochen), 1939- . II. Kochs, E.
(Eberhard), 1943- . RC386.6.E43C46 1994 616.8'047547--dc20 94-2610
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Preface
Research in electrophysiologic monitoring in anesthesia and intensive care has
focussed mostly on questions pertinent for patient care: First how to quantitate
drug effects on brain electrical activity and the degree of anesthetic-induced
suppression of the central nervous system. Second, how to monitor functional
impairment following cerebral ischemia and hypoxia. And third, how to differ
entiate between drug-induced effects on the central nervous system and deleteri
ous events related to reductions in cerebral blood flow and/or oxygen
delivery.
Even though progress has been achieved over the last 10 years in this field
and fascinating new techniques have been developed, it is still not clear which
monitor parameter will provide adequate information on the depth of anes
thesia and the analgesic level. Because the central nervous system has been one
of the main research areas in our department over the last 10 years, we
organized a workshop to summarize the latest developments in central nervous
system monitoring. This book comprises the topics of this workshop and is
intended to provide insight into the current status of central nervous system
monitoring, elucidating possible indications and delineating its limitations.
For more than 30 years a primary goal for intraoperative neurophysiologi
cal monitoring has been to get a warning when cerebral oxygen supply may be
hampered. This, obviously, is of special interest during surgical procedures
which may impair cerebral blood flow such as carotid endarterectomy, intra
cranial aneurysm, or spinal cord surgery. Many monitoring techniques have
been developed to predict imminent neuronal damage. In this sense, in
traoperative monitoring is used specifically to observe the response of the
central nervous system to surgical interventions. The hope was that peri
operative morbidity and mortality may be decreased by continuous or frequent
assessment of neuronal function. Some monitoring techniques, such as EEG or
evoked potential monitoring during carotid endarterectomies, have been shown
to be very sensitive and specific for the prediction of postoperative neurologic
outcome. For other surgical procedures the best monitoring parameter still has
to be defined.
A specific anesthesiologic goal which also has gained interest over the past
years is the assessment of the depth of anesthesia by neurophysiological
monitoring. The hope that the EEG may provide unique parameters has not
been substantiated because various anesthetic agents may produce different
VI Preface
EEG patterns. However, using computerized analysis methods, EEG frequency
descriptors (i.e., median frequency and spectral edge frequency) have been
advocated for the assessment of changes in depth of anesthesia. In closed-loop
feedback systems the median frequency has been shown to be useful for super
vising anesthetic drug administration. However, single parameters may not be
helpful for assessing sedative/hypnotic as opposed to analgesic effects. It has
become clear over the last years that the so-called intraoperative arousal
phenomena may be of concern when there is an inadequate depth of anesthesia.
In the EEG desynchronization with appearance of fast low wave activity has
been considered to indicate arousal phenomena. Recent studies have shown
that the shift to slower waves induced by surgical manipulations may also reflect
electrophysiologic arousal reactions. This has made it clear that at the time
being no single EEG parameter can be defined which unequivocally indicates
intraoperative arousal. Furthermore, the EEG may not reflect the level of
drug induced analgesic effects. Several studies suggest that evoked responses
hold promise for intraoperative assessment of the inadequate depth of anes
thesia. Early cortical auditory and somatosensory evoked responses change
in a graded manner with changes in depth of anesthesia. With few exceptions
these changes are not anesthetic specific. In addition, it has been shown that
surgical stimulation during an inadequate depth of anesthesia will reverse the
depressant effects of anesthetics. Further work has to show which anesthetic
technique will be most useful for achieving this goal in intraoperative monitor
ing. There is evidence that auditory evoked responses may indicate in
traoperative awareness. Specific cortical components of auditory evoked re
sponses seem to be related to auditory signal processing. Further studies have to
show if drug administration can be controlled by auditory evoked responses in
order to impair transmission of sensory stimuli to implicit memory. From
several studies on auditory evoked responses including the 40-Hz steady state
response, it can be concluded that these measures hold promise for assessing the
hypnotic effect of anesthesia. Somatosensory evoked responses have also been
shown to change in relation to anesthetic drug concentration in a non-agent
specific manner (exception: etomidate). It has been demonstrated in a few studies
that surgery may also offset the anesthetic induced depressant effects on
somatosensory evoked responses. However, it is unclear if these changes are
related to inadequate sedation. The stimulation of large mixed peripheral
nerves, such as is used for conventional somatosensory evoked response
monitoring, recruits different afferent pathways. In contrast, specific pathways
have to be stimulated to assess changes in nociceptive signal transmission.
Various studies have shown that somatosensory evoked responses following the
stimulation of C- and Ab- fibers correlate to drug induced changes in pain
perception. However, these cortical evoked responses are very vulnerable to
changes in psychophysiologic variables (i.e., attention, alertness, vigilance)
and are suppressed by virtually all anesthetics. Few studies have shown that
these evoked responses may be used for the assessment of analgesic treatment
effects during anesthesia.
Preface VII
In contrast to somatosensory evoked responses, transcranial stimulation
may be used for monitoring efferent pathways. This modality may be especially
useful during surgical procedures when motor pathways are at risk. However,
most anesthetics reduce the amplitudes of the evoked responses significantly. To
interpret electrophysiologic data, changes in systemic variables have to be
considered. Simultaneous recordings of brain function and cerebral blood flow
velocities or venous jugular bulb oxygen saturation may help in the detection of
deleterious effects.
Basic science and clinical applications complement each other. The syn
thesis of both, the exchange of scientific research and routine clinical practice,
will lead to a concept which will bring about the maximal benefit for patient
care. Therefore, one of today's pending challenges is to find monitoring tech
niques for clinical practice which allow the unequivocal assessment of central
nervous system function during anesthesia and intensive care.
It was O. W. Holmes who, in 1840, stated that the great thing in this world
is not so much where we stand, but in what direction we are going. In this sense
we understand the current trends in the development of central nervous system
monitoring techniques. It was the goal of this book to give an insight into the
ever developing process on new specific monitoring techniques and how they
may be used in the future. This in mind, we hope that this book will stimulate
scientists and physicians to continued research in the field of central nervous
system monitoring.
We are very grateful to the international group of distinguished speakers
and chairmen as well as to the audience for the excellent contributions and
discussions in this workshop. We are also much indebted to Mrs. L. Berger for
her technical assistance in preparing the workshop and her help in organizing
the publication of this book.
Hamburg, January 1994 JOCHEN SCHULTE AM ESCH
EBERHARD KOCHS
Contents
Part I Monitoring of the Electroencephalogram - Fundamentals
Interactions of Anesthetics at Different Levels
of the Central Nervous System
w.
B. Urban . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Principles of Central Nervous System Monitoring in Humans
R.-D. Treede . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
n
Part Techniques and Applications of
Electroencephalogram-Monitoring
Pharmacokinetic and Pharmacodynamic Interactions
Relevant To Cerebral Monitoring
H. J. M. Lemmens ........................................ 29
Electroencephalographic Feedback Control
of Anesthetic Drug Administration
H. Schwilden . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
The Use of Processed EEG in the Operating Room
M. J. Bloom ............................................. 56
Bispectral Electroencephalogram Analysis
for Monitoring Anesthetic Adequacy
J. M. Vernon, P. S. Sebel, S. M. Bowles, N. Chamoun,
and V. Saini ............................................. 69
Does Spectral Edge Frequency Assess Depth of Anesthesia?
G. M. Gurman ........................................... 78
"Paradoxical Arousal" During IsofluranejNitrous Oxide Anesthesia:
Quantitative Topographical EEG Analysis
P. Bischoff, E. Kochs, and J. Schulte am Esch ................... 91
Central Nervous System Monitoring; Reduction
of Information Content of Quantitative Electroencephalograms
for Continuous On-Line Display During Anesthesia
W. Dimpfel and H.-C. Hofmann............. .. .. ........... .. 103
x Contents
Part HI Monitoring of Stimulus Evoked Responses
Central Evoked Brain Potential as Overall Control
of Afferent Systems
B. Bromm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Indication for Evoked Potential Monitoring: A Surgical View
J. Zentner and J. Schramm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Anesthesia and Somatosensory Evoked Responses
E. Kochs and P. Bischoff ................................... 146
Peri-operative Anesthesiological Monitoring
of Auditory-Evoked Potentials
C. Thornton, P. Creagh-Barry, and D. E. F. Newton. . . . . . . . . . . . . . 176
The 40-Hz Auditory Steady State Response for Monitoring Level
of Consciousness: Methodological Considerations
C. Villemure, G. Plourde, and P. April. . . . . . . . . . . . . . . . . . . . . . . . . 187
Motor Evoked Potentials
C. J. Kalkman . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
Part IV Evoked Response: Special Applications
Auditory Evoked Potentials to Monitor Intra-operative Awareness
D. Schwender, S. Klasing, C. Madler, E. Poppel, and K. Peter ...... 215
Evoked Potential Monitoring for Vascular Surgery
M. Dinkel, H. Loder, H. Langer, H. Schweiger, and E. Riigheimer 230
Assessment of Analgesic Drug Treatment
E. Scharein .............................................. 248
Long-Term Monitoring in Intensive Care Patients:
Electroencephalogram, Evoked Responses, and Brain Mapping
E. Facco, M. Munare, F. Baratto, A. U. Behr, and G. P. Giron 257
Part V Present and Future Trends in Cerebral Monitoring
Present and Future Trends in Multimodal Cerebral Monitoring
in Anesthesia and Intensive Care
G. Litscher, G. Schwarz, W. Marte, G. Pfurtscheller,
and W. F. List ........................................... 283
Jugular Bulb Venous Oxygen Saturation
and Transcranial Doppler Ultrasonography
in Neurosurgical Patients
N. M. Dearden . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292
Contents XI
Transcranial Doppler Sonography: Monitoring
of Cerebral Perfusion
C. Werner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314
BRAINDEX - An Expert System for Supporting
Brain Death Diagnosis
G. Rom, R. Grims, G. Schwarz, and G. pfurtscheller . . . . . . . . . . . . . . 326
Subject Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335
Contributors
BISCHOFF, P., Dr.
Abteilung fiir Anasthesiologie, Universitats-Krankenhaus Eppendorf,
Martinistr. 52, 20246 Hamburg, Germany
BLOOM, M.J., M.D., Ph.D. Assistant Professor
School of Medicine, Departments of Anesthesiology jCCM,
University of Pittsburgh, Pittsburgh, PA 15213, USA
BROMM, B., Prof. Dr. Dr.
Physiologisches Institut, Universitats-Krankenhaus Eppendorf, Martinistr. 52,
20246 Hamburg, Germany
DEARDEN, N.M., M.D.
Dept. of Anaesthesia, Leeds General Infirmary, Leeds LS12 4AD, Scotland
DIMPFEL, W., Prof. Dr.
ProScience, Private Research Institute, Linden, 35390 Giessen, Germany
DINKEL, M., Dr.
Institut fiir Anasthesiologie der Universitat Erlangen - Nurnberg,
Krankenhaus Str. 12, 91054 Erlangen, Germany
DOENICKE, A., Prof. Dr.
Anasthesiologische, Abteilung, Chirurgische Poliklinik der Universitat,
Pettenkoferstr. 8a, 80336 Munchen, Germany
F ACCO, E., M.D.
1st. Anestesiologia e Rianimazione, Universita di Padova, Via C. Battisti 267,
35121 Pado va, Italy
GURMAN, G., M.D., Prof.
Division of Anesthesiology, Soroka Medical Center, Beer-Sheva 84101, Israel
HEMPELMANN, G., Prof. Dr.
Institut fur Anasthesiologie, Universitatskliniken, Klinikstr. 29, 35392 Giessen,
Germany
Description:Research in electrophysiologic monitoring in anesthesia and intensive care has focussed mostly on questions pertinent for patient care: First how to quantitate drug effects on brain electrical activity and the degree of anesthetic-induced suppression of the central nervous system. Second, how to mon
