Untoward Events
One of the suggested reasons for monitoring the brain of the anesthetized
patient is to enable detection of injuries to the nervous system that would not be
otherwise apparent. Although there are hundreds of such case reports in the literature
and many in our experience, the cost-effectiveness of such monitoring is not clear.
In a case being prepared for publication, severe electroencephalographic changes
occurred at the beginning of a carotid endarterectomy, before surgical incision,
and were not associated with any other vital sign changes or hypotension. Immediate
angiography revealed acute carotid occlusion and completely changed the operation
performed, and the patient recovered completely. Some intraoperative events may
lead to a CNS insult that, if detected early, can be rapidly reversed or treated
to prevent permanent injury. However, given the rarity of such
TABLE 38-5 -- Criteria for determination of brain death
|
Absent cerebral and brainstem functions |
|
Well-defined, irreversible cause |
|
Persistent absence of all brain function after observation or
treatment |
|
Hypothermia, drug intoxication, metabolic encephalopathy, and
shock excluded |
|
Adapted from Darby JM, Stein K, Grenvik A, et al: Approach
to management of the heart beating "brain dead" organ donor. JAMA 261:2222, 1989. |
events, it is extremely unlikely that such monitoring could be shown to be beneficial
in any foreseeable randomized trial. If the at-risk patient can be identified preoperatively,
electroencephalographic monitoring may be useful in detecting untoward CNS events
during anesthesia, such as a new stroke after elective general surgery.
