An electroencephalographic classification for coma

Abstract

Background: The assessment of thalamocortical function in comatose patients in the intensive care unit (ICU) can be difficult to determine. Since the electroencephalogram (EEG) affords such assessment, we have developed an EEG classification for comatose patients in our general ICU. Methods: One hundred EEGs were classified in a blinded fashion by two EEGers, using our method and that of Synek. Interobserver agreement was assessed using kappa score determination. Results: Kappa scores were 0.90 for our system and 0.75 for the Synek system. (The Kappa score represents the inter- rater agreement that is beyond chance; 0.90 is almost perfect agreement, while 0.75 is substantial agreement). Conclusion: Our system for classifying EEGs in comatose patients has a higher interobserver reliability than one that was previously published. This EEG classification scheme should be useful in clinical electrophysiological research involving ICU patients, allowing for internal consistency and comparisons among centres.