Practical aspects of working in
the operating room
Intraoperative neurophysiologic
monitoring
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Electrophysiologic recordings in an electrical hostile
environment
Electrophysiologic recordings in an anesthetized
patients
The need to obtain interpretable records in a short
time
Interpretation of results must occur promptly
What changes to report and what not to report?
Communication with the surgeon
Relation with the anesthesia team
Relations with other members of the operating
room team
Electrophysiologic recordings in
an electrical hostile environment
• Survey an operating room that you not
familiar with for sources of electrical
interference
– Best done the evening before an operation
• Always be in the operating room early
enough to solve unexpected problems
• Always monitor the recorded potentials
directly during an operation
– EEG tells the signature of interference; averaged potentials
do not
Find the source of interference
Electrophysiologic recordings in
an anesthetized patient
• Advantages:
– Can use needle electrodes freely
– Can stimulate peripheral nerves
supramaximal
• Disadvantages:
– Can cause injury by too strong electrical
stimulation of nerves or CNS
The need to obtain interpretable
records in a short time
• Use optimal stimulus and recording
parameters
• Reduce noise as much as possible at its
source
• Use optimal placement of electrode wirings
• Plan your recordings ahead to avoid waste of
time
Interpretation of results must
occur promptly
• Prepare yourself ahead of time so you
understand the recordings and their
interpretation
• Understand the different kinds of
changes that can occur and their
meaning with regard to pathologies
What to report to the surgeon?
INFORMATION THAT IS OF
VALUE
• Changes in recorded potentials
• All unusual events
• In case of dramatic changes:
– First assume a biologic cause and always
notify surgeon immediately
– Then check equipment etc.
What changes to report?
• Changes in the recorded potentials that
are larger than the normal (small)
variations
What not to report?
• Data without interpretation
A stream of numbers without
interpretation is of little value
Communication with the
surgeon
• The surgeon is not a physiologist
• Therefore: Provide interpreted results,
not raw data
• Place the observed changes in
relationship to the ongoing operation
• You must know the basic steps in the
operation you are monitoring
Interpretation of pathologic
changes
• Which parameters are important?
• What to use as reference values?
• What is significant?
Change in relation to what?
• How to get a representative baseline
Which parameters are
important?
• Latency
• Amplitude
Non-pathologic changes
• Change in anesthesia
• Change in body temperature
Artifacts
• Stimulus artifacts
• Movement artifacts
• Irrigation with cold saline may cause
changes in recorded potentials
False positives
False negatives
• Limited relevance for intraoperative
monitoring
Relation with the anesthesia
team
• Always discuss a case with the
anesthesia team before an operation
– What kind of anesthesia they want to use
– How that will influence your work
For that you must know the basics of modern
anesthesia techniques
Relation with the anesthesia
team
• Interchange of information
– You can provide information of value for
the anesthesia team
– They can let you know of changes in vital
signs and in anesthesia regimen
Relation with the anesthesia
team
• Discuss each operation with the
anesthesiologists in advance
• Ask to be informed about any changes in the
anesthesia regimen that may occur during an
operation
• Watch their displays and understand what
they mean
• Treat the anesthesiologists as your friends
and try to understand their situation and
problems
Relations with other members of
the operating room team
• Keep a good relationship with all nurses in
the operating room (they control the
environment)
• Do not be afraid of offering a helping hand
• Remember that they (and you) are all there
for one single purpose, namely to provide the
best possible care for the patient
Practical aspects of working in
the operating room
• Should the person who is responsible
for monitoring be present in the
operating room? YES
• Can monitoring be done by watching a
display of recorded potentials in an
another room? NO