Korean J Thorac Cardiovasc Surg.
2001 Jun;34(6):465-471.
The Significance of Electroencephalography in the Hypothermic Circulatory Arrest in Human
- Affiliations
-
- 1Department of thoracic and cardiovascular surgery, Sejong General Hospital, Puchon.
- 2Department of thoracic and cardiovascular surgery, Gil Medical Center, Gachon Medical School .
- 3Department of thoracic and cardiovascular surgery, Medical College, Hanyang University.
Abstract
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BACKGROUND: Hypothermia protects the brain by suppressing the cerebral metabolism and it
is performed well enough before the total circulatory arrest(TCA) in the operation of aortic
disease. Generally, TCA has been performed depending on the rectal or nasopharyngeal
temperatures; however, there is no definite range of optimal temperature for TCA or an
objective
indicator determining the temperature for safe TCA. In this study, we tried to
determine the optimal range of temperature for safe hypothermic circulatory arrest by using
the intraoperative electroencephalogram(EEG), and studied the role of EEG as an indicator
of optimal hypothermia.
MATERIAL AND METHOD: Between March, 1999 and August 31, 2000,
27 patients underwent graft replacement of the part of thoracic aorta using hypothermia and
TCA with intraoperative EEG. The rectal and nasopharyngeal temperatures were monitored
continuously from the time of anesthetic induction and the EEG was recorded with a
ten-channel portable electroencephalography from the time of anesthetic induction to
electrocerebral silence(ECS).
RESULT: On ECS, the rectal and nasopharyngeal temperatures
were not consistent but variable(rectal 11degree C -25degree C, nasopharynx 7.7degree C -23degree C). The
correlation between two temperatures was not significant(p=0.171). The cooling time from
the start of cardiopulmonary bypass to ECS was also variable(25-127min), but correlated
with the body surface area(p=0.027).
CONCLUSION
We have found that ECS appeared at
various body temperatures, and thus, the use of rectal or nasopharyngeal temperature were
not useful in identifying ECS. Conclusively, we can not fully assure cerebral protection
during hypothermic circulatory arrest in regards to the body temperatures, and therefore, the
intraoperative EEG is one of the necessary methods for determining the range of optimal
hypothermia for safe circulatory arrest.