Bispectral Index Scale Variations in Patients Diagnosed With Brain Death

IntroductionBrain death (BD) is defined as the total irreversible loss of brain stem function. According to the Greek legislation, BD diagnosis is based on clinical criteria that test brain stem function. Bispectral Index Scale (BIS), a parameter derived from a mathematical analysis of the electroengephalogram depicts brain activity. The aim of our study was to record BIS alterations in brain-dead paitents.MethodsThirty-five brain dead patients according to the clinical criteria were included in this study. All patients were hemodynamically stable, normothermic, and normocapnic, free of oxygenation disturbances and electrolyte abnormalities. Continuous BIS monitoring (BIS XP, A-2000, Aspect Medical Systems, Newton, Mass, USA) was performed in all patients for periods ranging from 24 to 36 hours.ResultsBIS values were 0 for the majority of the study period in all patients. However, in 23 patients the BIS value exceeded 30 for more than 30 minutes. This increase could not be attributed to any external stimulation.ConclusionBIS is a noninvasive, easily interpreted method to monitor cerebral activity. According to our results, BIS could be helpful in BD confirmation but cannot replace the valid clinical tests, which are consistent with Greek legislation for this diagnosis.