Abstracts

Rationale: Cardiac arrest affects a very high number of patients annually in the United States. It is a major cause of mortality and survivors often suffer from neurological deficits. Nonconvulsive seizures and abnormalities in the electroencephalogram (EEG) are also observed in many patients, and have been used to prognosticate the outcome. In this study, we use time-locked video and EEG monitoring to characterize seizures and alterations in the EEG in a mouse model of cardiac arrest (CA) and cardiopulmonary resuscitation (CPR). Methods: CA was induced in 6-12 week old male mice by injection of 50 microL 0.5 M KCl via the jugular catheter. Eight minutes after induction of CA, CPR was begun by injection of 0.5-1ml of epinephrine solution, chest compression at a rate of 300/min, and ventilation with 100% oxygen. Cardiac massage was discontinued immediately upon restoration of spontaneous circulation. To record EEG, electrodes were implanted over the motor cortex of each hemisphere and in CA1 region of the right hippocampus one week before CA-CPR procedure. A 24 hour baseline video-EEG recording was obtained before the mouse was subjected to CA-CPR. Beginning 8-10 minutes after completion of the CA-CPR procedure, the mice were continuously monitored by video-EEG for 72 hours, and for 24 hours continuously at 10, 20 and 28 days after the CA-CPR. Video-EEG records were examined manually to determine the presence of spikes and sharp waves, and electroclinical and purely electrographic seizures. EEG power in the 1-50 Hz frequency band was calculated using a fast Fourier transform (FFT) algorithm written using Visual Basic subroutines. Results: Suppression of the background EEG and appearance of spikes and sharp wave activity across three EEG channels was observed in all mice immediately following CA-CPR. One mouse out of eight developed a purely electrographic seizure in the acute period after CA-CPR. At 10 days after the CA-CPR, 25% of the mice developed clinical and nonconvulsive seizures that remained restricted to the hippocampus. Only 50% mice survived beyond 72 hours following CA-CPR procedure. We are currently analyzing the data to determine prognostic significance of EEG power. Conclusions: Our mouse model of CA-CPR replicates seizure and EEG characteristics of the human disease. Funding: None