EEG under anesthesia

David Mckalip dmmckali at gibbs.oit.unc.edu
Fri Feb 11 11:19:51 EST 1994


In article <1994Feb10.212432.58482 at kuhub.cc.ukans.edu>,
 <merkley at kuhub.cc.ukans.edu> wrote:
>What happens to the EEG under general anesthesia?
>Thanks in advance,
>
>Matthew Merkley, M.D.       merkley at kuhub.cc.ukans.edu
>  Department of Psychiatry  --------------------------
>    University of Kansas School of Medicine -- Wichita
>

Overall, General anesthesia produces a slowing of the wave activity. 
However, the degree of slowing, the anatomical locations and the rate are
variable depending on locations.  We routinely use EEG during carotid
endarterectomy (removal of carotid artery atherosclerotic plaque) to monitor
for cerebral ischemia during carotid clamping. 
Patients are generally kept as light as possible during the operation to
preserve EEG waveforms.  If the brain can tolerate the loss of flow from
one artery due to intact collateral flow through the circle of willis, no
EEG changes are seen.  However, if the brain becomes ischemic, the EEG
waveforms slow and flatten.  A shunt is then placed to bypass the clamped
artery.  That about taps my knowledge on the subject.
  A good reference for review is a chapter in "CLINICAL NEUROANESTHESIA".
Cucchiara, Roy F., Michenfelder, J.D.  1990.  Published by Churchill
Livingstone, New York, Edinburgh, London, Melbourne.

David McKalip
Division of Neurosurgery
UNC-Chapel Hill




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