Electroencephalography: the worst traditionally recommended tool for brain death confirmation

Excerpt

In their current contribution to Intensive Care Medicine Wennervirta et al. [1] observe that the bispectral index (BIS), state entropy, and response entropy differ from zero in most brain-dead (BD) patients, even excluding cases with persistent residual electroencephalographic (EEG) activity. The authors judiciously explain their observation by the superimposition on the EEG of artifacts of various origins. Actually, that BIS and entropy parameters add nothing to visual EEG analysis for BD diagnosis was fully predictable: electrocerebral silence is usually not associated with a flat EEG, and only a flat EEG in the frequencies tested by BIS or entropy could have given rise to zero values of these indices. The real surprise was that several patients had zero values, considering such large contamination by artifacts. This is likely due to the proximity between active and reference electrodes; this is in conflict with classical recommendations for the use of EEG in BD diagnosis [2], which require large interelectrode distances. This constitutes one further argument to reject such EEG-derived parameters for BD confirmation. …