Abstracts

Rationale: Therapeutic hypothermia (TH) seems to improve neurological outcome in patients with cardiac arrest (CA). However, sedation, which is necessary in this setting, limits the accuracy of neurological examination, so that tools are needed to help in determining prognosis. Continuous EEG monitoring (cEEG) has been developed recently and may be useful for this purpose. Methods: This single-center retrospective study included 92 patients with CA, who were treated with TH and underwent cEEG. cEEG was initiated as soon as possible after the initiation of TH and continued at least until restoration of normothermia (>37°). The following EEG characteristics were recorded: variability/reactivity, isoelectric EEG, burst suppression (BS) pattern and epileptic activity (EA: generalized periodic discharges, seizures and spikes). EEG background was defined as malignant (non variable or unreactive/isoelectric/BS) or benign (variable/reactive). EEG findings were divided into groups according to the time period after CA (0-8 hours, 8-16 hours, 16-24 hours, 24-48 hours). Neurological outcome was assessed using Glasgow-Pittsburgh Cerebral Performance Categories (CPCs) at 3 months. Good neurological outcome (GNO) was defined as CPC 1-2 and poor neurological outcome (PNO) as CPC 3-5. Results: Of the 92 patients, 26 (28%) had GNO. A malignant EEG background was more frequent in the group of patients with PNO than in those with GNO at all time points. The positive predictive value (PPV) of a malignant EEG background for PNO was > 94% over the study period. Only one patient with an initially flat EEG had GNO; in this patient, the EEG background rapidly evolved from malignant to benign. The proportion of patients with a benign background was similar among patients with PNO and those with GNO. The PPV of EA for PNO was also high (>92%), but the presence of EA did not significantly increase the PPV of malignant background for PNO. None of the patients with a benign background and periodic discharges or seizures survived. Conclusions: Prognosis after CA is especially poor in the presence of a malignant EEG background or seizures/generalized periodic discharges. These observations are valid at any time during the first 48 hours after CA, even in the first few hours.