Abstract 12398: Cardiopulmonary Resuscitation Duration Determines Phenotype of Post-Arrest Brain Injury

Introduction: Patients resuscitated from out-of-hospital cardiac arrest (OHCA) have variable severity of brain injury. Signatures of severe injury on brain imaging and EEG including diffuse cerebral edema and burst suppression with identical bursts (BSIB). Current therapies for these patterns of injury are inadequate and patient outcomes are poor. Hypothesis: We hypothesize distinct phenotypes of brain injury are associated with increasing CPR duration. Methods: We identified from our prospective registry OHCA patients treated between January 2010 to July 2019. We abstracted CPR duration, best neurological examination < 6 hours from OHCA, initial brain CT grey-to-white ratio (GWR), and initial EEG pattern. We defined cerebral edema as GWR <1.20. We defined BSIB according to American Clinical Neurophysiology Society guidelines. We considered four phenotypes on presentation: awake; comatose with neither BSIB nor cerebral edema; BSIB; and cerebral edema. BSIB and cerebral edema were considered as non-mutually exclusive outcomes. We compared duration of CPR across groups using Kruskal-Wallis tests with Bonferroni correction for multiple hypothesis testing. We report the probability of presenting phenotype at the median CPR duration for each group using local regression. Results: We included 2,721 patients, of whom 582 (21%) were awake, 1,428 (52%) had coma without BSIB or edema, 372 (14%) had BSIB and 356 (13%) had cerebral edema. Only 47 (2%) had both BSIB and edema. Median CPR duration was 16 [IQR 8-28] minutes overall. Median CPR duration increased in a stepwise manner across groups: awake 6 [3-12] minutes; comatose without BSIB or edema 16 [9-27] minutes; BSIB 21 [14-30] minutes; cerebral edema 32 [22-46] minutes (all P <0.001). The probability of observing each phenotype at the median CPR duration for each was: awake (0.42); comatose without BSIB or edema (0.72); BSIB (0.34); cerebral edema (0.29). Conclusions: The brain injury phenotype is related to CPR duration, which is a surrogate for severity of ischemic injury. The sequence of most likely brain injury phenotype with progressively longer CPR duration is awake, coma without BSIB or edema, BSIB, and finally cerebral edema.