RESUMO
OBJECTIVE: The aim of this study is to evaluate the usefulness of a spectral function detecting cerebral hypoperfusion. METHODS: Continuous electroencephalographic monitoring was employed during 47 consecutive carotid endarterectomies. Patients were assigned to 3 different groups according to the entity of electroencephalographic changes during carotid clamping (major changes: group A; moderate changes: group B; no change: group C). The desynchronization function, indicating the reduction of the 8-15 Hz band power, and the desynchronization index were calculated. RESULTS: Group A function decreased within 20s from clamping, with a constant slope (7.14). Desynchronization indexes were: 76.85% (group A), 40.23% (group B) and 15.29% (group C). Difference among groups was statistically significant (P < 0.0001). A case of syncope due to asystole is also reported, showing the same pattern in the descending phase of the function. CONCLUSIONS: The stereotyped time course of the desynchronization function describes the cerebral reaction to significant blood flow reduction. Values of desynchronization index exceeding 65% seem to correctly detect patients with cerebral hypoxic risk. SIGNIFICANCE: The analysis of the 8-15 Hz band desynchronization is helpful in the evaluation of cerebral hypoperfusion during carotid endarterectomy. This method could be employed in monitoring different clinical situations of ischemia.
