Abstract 287: Bimodal Brain Monitoring Using Portable EEG and Cerebral Oximetry During Cardiopulmonary Resuscitation (CPR): A Pilot Study

Background: There is a need to monitor brain resuscitation during CPR. Furthermore, 10% of CA survivors report cognitive activity and 2-3% report consciousness during CPR. Methods: Using data from a prospective study (AWARE-II) with bimodal brain monitoring during CPR (EEG, [Massimo] and regional cerebral oxygenation [rSO2 normal 60-80%]) using cerebral oximetry [Nonin]), we sought to identify EEG rhythms, their progression over time, and underlying rSO2 thresholds. Inclusion criteria: In hospital CA, ≥ 18 years. Raw EEG data were captured as images (1/second) during CPR pauses, while rSO2 was captured continuously. Results: 38 patients were recruited; mean age 69±16 with duration of CPR (10-60 mins). We captured 362 EEG images. 91 (25%) were artifacts. Among the 271 interpretable images, there were 13 EEG rhythms placed into 6 groups based on their association with normal/near normal, seizures, coma, absence of cortical activity as follows: Group 1 (Non-epileptogenic): Theta, Delta, Alpha, Group 2 (Epileptogenic/Spike and Wave): Generalized Rhythmic Delta Activity (GRDA) + Spike (S), Delta + S, Theta + S, Burst Suppression with GRDA + S, Group 3 (Flat-line): Marked Voltage Attenuation (MVA), Group 4 (Coma State): Burst Suppression (w/ GRDA, Delta, and/or Theta), Group 5: GRDA, Group 6: Generalized Periodic Discharges (GPD). MVA/absence of activity was observed throughout CPR time and across all rSO2 ranges. Normal/near normal (non-epileptogenic) including alpha rhythms (which to our knowledge is described for the first time), and epileptogenic rhythms were observed with rSO2>30% Conclusions: While unclear whether non-epileptogenic rhythms are associated with transient periods of ROSC, however real-time bimodal brain monitoring provides insights regarding brain resuscitation and its dynamic interaction with patient factors. While ischemia may cause epileptogenic activity, there are periods of normal/near-normal cortical activity despite prolonged CPR >45-60 mins. A minimal threshold of brain oxygen delivery (rSO2>30%) may be required for cortical activity. These data raise questions regarding assumptions of irreversible brain damage with prolonged CPR, as well as the possibility of consciousness and cognitive activity during CPR.