Abstracts

Rationale: Cardiac arrest in the pediatric population puts children at risk of hypoxic injury and electrographic seizures. While the neurologic sequelae of cardiac arrest in adults are well established there is still a paucity of information in children. The aim of this study is to characterize the clinical and electrographic features of critically ill children following cardiac arrest.Methods: Retrospective observational study of children ages 1 month to 21 years who had a cardiac arrest and underwent a clinically indicated continuous electroencephalography (cEEG) (defined as greater than 3 hours of uninterrupted EEG) in the pediatric and cardiac intensive care units at Boston Children’s Hospital from January 2011 to December 2013. In patients with multiple episodes on cEEG, only the first recording was considered. Electrographic seizures were defined as any seizure detected on cEEG, whether electro-clinical or electrographic-only. Electrographic status epilepticus (ESE) was defined as a continuous seizure lasting greater than 30 minutes or seizures totaling 50% of a 1 hour epoch.Results: Fifty three children were studied (62% male) with a median age of 2.1 years. The main indications for admission were cardiac arrest in 35 patients (66%), respiratory failure in 8 and sepsis in 4 patients. The median length of ICU stay in the ICU was 19.3 days. Twenty four patients had congenital heart disease and 31 required extracorporeal membrane oxygenation (ECMO). Twenty three patients suffered hypoxic injury and 12 patients underwent therapeutic hypothermia. The main indications for cEEG were to evaluate for nonconvulsive seizures in 38 patients, characterization of events with clinical concern for seizure in 24, and assessment of response to treatment in 1. In 10 patients dual indications were apparent. Six patients had a burst suppression background and 21 patients (40%) had epileptiform discharges. The median duration of EEG monitoring was 24 hours. Electrographic seizures were detected in 5 patients (9.4%) of whom 4 were electrographic only. One patient met criteria for ESE. Eighty percent of patients with seizures had epileptiform discharges. The typical seizure duration was less than 60 seconds and with 60 percent having a generalized onset. The minimum time to first seizure was 30 minutes with the maximum being 59 hours. The overall mortality was 49%. Of the 12 patients undergoing hypothermia no seizures were detected.Conclusions: Children presenting with cardiac arrest are at risk for electrographic seizures. The majority of seizures are electrographic only, which would go undetected without continuous monitoring. The data indicates that EEG monitoring for up to 60 hours post arrest could be warranted to assist in detecting and subsequently treating these events. No patients in the cohort of those treated with therapeutic hypothermia had seizures, suggesting a possible antiepileptogenic effect.