Electroencephalogram Characteristics in Critical Ill Patients Before Cardiac Arrest: A Case Series

Background/Objectives. To illustrate characteristic electroencephalogram (EEG) features in patients prior to their first cardiac arrest. Methods. We identified 15 patients who suffered cardiac arrest during continuous EEG at our institution from June 2016 to June 2019. Eight patients were excluded due to co-administration of intravenous anesthetics (which may confound EEG) or if they had a previous prolonged cardiac arrest (>5 minutes) during the same hospitalization. We collected background information, analyzed the time span and vital signs between the initial background change and cardiac arrest. Results. The time span range (minutes) from initial background change to cardiac arrest was 4 to 483 (average 128.9), initial background change to suppression was 0 to 372 (average 75.6), suppression to cardiac arrest was 1 to 140 (average 53.3), suppression to complete suppression was 0 to 66 (average 20.4), and complete suppression to cardiac arrest was 1 to 111 (average 32.9). Three patients showed background changes more than 160 minutes before cardiac arrest. All patients showed progressive heart rate (HR) decline at or before the beginning of suppression on EEG. HR (beats/min) (mean +/- SE) at background change, background suppression, complete suppression, and cardiac arrest was 86.3 +/- 7.5, 63.9 +/- 7.5, 36.0 +/- 6.8, and 0, respectively. We found statistically significant HR changes (P < .05) between background change and complete suppression time points. Conclusions. Our data indicate that EEG pattern change can occur minutes to hours before the initial cardiac arrest. These patterns may be due to progressive cerebral ischemia. Further studies with broad-scale monitoring of vital signs and evoked potentials may help develop models for predicting cardiac insufficiency.