Electroencephalographic changes and their regional differences during pediatric cardiovascular surgery with hypothermia

Monitoring brain function by EEG is an important means of preventing cerebr al insults in pediatric cardiovascular surgery. Vile studied intraoperative EEGs changes and their regional differences associated with hypothermia an d brain ischemia. The subjects of this study consisted of 13 children rangi ng in age from 4 months to 4 years and 6 months. Multi-channel EEGs were re corded using a portable digital EEG system, and the EEG changes were examin ed by visual inspection and computerized analyses. The results were as foll ows. (1) During cooling, a discontinuous EEG pattern was transiently observ ed in four patients, and this phenomenon indicated rapid suppression of cer ebral function and subsequent adaptation. (2) Regarding the patterns of cha nge in equivalent potentials induced by hypothermia: there were two differe nt patterns depending on the degree of hypothermia, and the borderline rect al temperature was found to be around 32 degreesC. (3) During cooling, regi onal differences in the changes in equivalent potentials were observed in n ine patients. A decrease in slow waves was marked in the occipital head are a, and a decrease in fast waves was prominent in the anterior head area. (4 ) Arterial hypotension caused transient EEC abnormalities. Of them, bilater ally synchronous rhythmic high voltage slow waves were remarkable and exhib ited bifrontal or bicentral dominance. (5) The EEG changes induced by hypot hermia were influenced not only by the rectal temperature itself, hut also by the rate of change in rectal temperature, and we speculated that this ph enomenon was a result of adaptation. In intraoperative EEG monitoring, thes e findings constitute the basis fur early detection of a cerebral hypoxic-i schemic stare during pediatric cardiovascular surgery. (C) 2001 Elsevier Sc ience B.V. All rights reserved.