RESUMO
BACKGROUND: Flumazenil is a competitive benzodiazepine receptor antagonist, reverts the sedation effects of benzodiazepines and its effect on electroencephalographic (EEG) patterns is controversial. The purpose of this study was to describe flumazenil's effect on EEG patterns of patients undergoing conscious sedation. METHODS: Ten voluntary patients, aged 16-23, at elective oral surgery had conscious sedation with midazolam and local anesthesia. After the procedure, sedation was reversed with flumazenil. Each patient had 4 EEGs of 4 minutes each: baseline, 5 minutes after midazolam, prior to flumazenil, and 8 minutes after flumazenil. A clinical neurophysiologist interpreted EEGs blinded to time. RESULTS: Eight patients had an awake and 2 had an awake and drowsy normal EEG. After midazolam all developed a diffuse beta wave and alpha wave attenuation or dropout. Prior to flumazenil 7 presented diffuse beta and scattered theta waves, and 3 an awake pattern (procedure required > 30 minutes). After flumazenil, reversal of beta and theta waves and appearance of alpha waves was noted; no changes occurred when procedure lasted more than 30 minutes. One patient presented with diffuse theta waves, 6 Hz. CONCLUSIONS: Flumazenil reverts midazolam EEG changes if administered < 30 minutes after midazolam administration, midazolam-induced EEG changes revert spontaneously after 30 minutes, and flumazenil may precipitate theta activity.