Current guidelines recommend the use of sedatives and neuromuscular blocking agents to avoid shivering during therapeutic hypothermia in cardiac arrest victims. Therefore, it is difficult to detect seizure and the frequent or continuous EEG monitoring is recommended. However, it is difficult to follow this recommendation in most clinical situations due to the lack of specialized devices and persons. The purpose of this study is whether SEDline (frontal 4-channel EEG device) has a diagnostic value to detect seizure during therapeutic hypothermia in cardiac arrest victims.

1. Treatment of cardiac arrest victims Enrolled patients receive basic and advanced cardiac life support according to the 2010 American Heart Association (AHA) Guidelines for Cardiopulmonary Resuscitation (CPR) and Emergency Cardiovascular Care (ECC).

   After acquiring sustained return of spontaneous circulation (ROSC), the patients are immediately admitted to the ICU and are provided postresuscitation care including mild therapeutic hypothermia for 24 hours post-ROSC.

   During therapeutic hypothermia, their core temperatures are maintained from 32 to 34°C.

   Then rewarming is conducted (< 0.25°C/hour) till core temperature 36.5°C. To avoid shivering, we use sedatives and neuromuscular blocking agents during the therapeutic hypothermia.

2. Conventional EEG Conventional EEG is conducted for 30 minutes at

   1) During therapeutic hypothermia and rewarming (within 72 hours after cardiac arrest) Then, the results are interpreted by a neurologist for the presence of seizure.

3. SEDline SEDline is monitored during the simultaneous period with the conventional EEG. Data retrieved from the SEDline are blindly interpreted by 3 investigators to determine the presence of seizure activity.

   The presence of seizure activity in SEDline is determined by the definition

   1. Electrographic seizure: rhythmic discharge or spike and wave pattern with definite evolution in frequency, location, or morphology lasting several seconds.
   2. Spike: Transient, clearly distinguishable from background activity, with pointed peak at conventional paper speeds and a duration of 20 to less than 70 ms

4. Anti-epileptic drug The use of anti-epileptic drugs is guided by the results of conventional EEG or the presence of clinically seizure-like movement

5. Gold standard The presence of Seizure identified in conventional EEG.

6. Primary outcome The diagnostic performance of SEDline to detect seizure will be tested: Sensitivity, specificity, positive predictive value, negative predictive value, accuracy, and area under receiver operating characteristics curve (AUC).

Inclusion Criteria:

• Consecutive comatose patients admitted to the emergency ICU for postresuscitation care following successful cardiopulmonary resuscitation after nontraumatic out-of-hospital and in-hospital cardiac arrest.
• Cardiac arrest is defined as cessation of cardiac mechanical activity, confirmed by the absence of a detectable pulse, unresponsiveness, and apnea.

Exclusion Criteria:

• Age < 18 years old
• Contraindication to therapeutic hypothermia: active life-threatening bleeding, septic shock, or refractory fatal arrhythmia..
• Intracranial pathology including hemorrhage or tumor
• Visible generalized seizure before the study enrollment
• Advanced directives to withdraw life-sustaining treatment
• No informed consent

Comatose cardiac arrest survivors admitted to a 12-bed emergency intensive care unit of Seoul National University Hospital, Seoul, Republic of Korea.

After discussion with Masimo

44 provided informed consents. Among them 5 were withdrawn. 1 death before EEG, 2 relative withdrew patient, 1 combined septic shock, and 1 patient did not perform EEG within 72 hours.

Finally 39 patients were enrolled in this study.

30 days

Since the SEDline system provides 4-channel-processed EEG monitoring in the frontal area, focal seizures could not be detected and spatial localization of the seizure might be difficult.