AHA: Consciousness, Awareness May Occur During Cardiac Arrest

THURSDAY, Nov. 17, 2022 (HealthDay News) -- Consciousness has been captured during cardiac arrest, according to a study presented at the American Heart Association Resuscitation Science Symposium 2022, held from Nov. 5 to 6 as part of the annual meeting of the American Heart Association. The study has been accepted for publication in a future issue of Circulation.

Sam Parnia, M.D., Ph.D., from New York University Grossman School of Medicine in New York City, and colleagues examined consciousness and its underlying electrocortical biomarkers during cardiopulmonary resuscitation (CPR). Independent audiovisual testing of awareness, including explicit and implicit learning using a computer and headphones, was incorporated with continuous real-time electroencephalography (EEG) and cerebral oxygenation (rSO₂) monitoring into CPR during in-hospital cardiac arrest (IHCA). Interviews were administered to survivors to examine recall of awareness and cognitive experiences.

Overall, 53 of 567 IHCAs survived (9.3 percent); 28 (52.8 percent) completed interviews and 11 (39.3 percent) reported memories/perceptions that indicated consciousness. The researchers identified four categories of experiences: emergence from coma during CPR (two of 28; 7.1 percent) or in the postresuscitation period (two of 28; 7.1 percent); dream-like experiences (three of 28; 10.7 percent); and transcendent recalled experience of death (six of 28; 21.4 percent). These categories were reinforced by 126 community cardiac arrest survivors in a cross-sectional study; survivors also identified another experience: delusions (misattribution of medical events). The ability to examine implicit learning was limited by low survival. Normal EEG activity consistent with consciousness emerged as long as 35 to 60 minutes into CPR despite marked cerebral ischemia (mean rSO₂ = 43 percent).

"Our results offer evidence that while on the brink of death and in a coma, people undergo a unique inner conscious experience, including awareness without distress," Parnia said in a statement.

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