A new study reveals some interesting insights into the experiences of patients undergoing cardiac arrest (CA). The study is presented as the first of its kind, investigating conscious memories of CA patients who received CPR. The study looked at 53 survivors of CA, with 28 of the survivors being interviewed. Unique to the study, researchers placed headphones over participants’ ears during resuscitation to see if they could recall certain words played during the resuscitation, as well as displaying 10 images on a tablet to see if they could later recall any of the images. Only one of the participants interviewed could recall the three-word sound sequence that was played, and none could recall the images. However, 11 of the interviewees (nearly 40%) did report memories or feelings that suggested some level of consciousness. The researchers divided these into four categories: 1) consciousness during CPR, 2) post CPR consciousness, 3) dream-like experiences, and 4) transcendent experiences where the participant recalled experiencing death. Six of the 28 survivors (over 20 percent) recalled these transcendent experiences. Researchers also analyzed reports of 126 other CA survivors reporting their experiences. EEGs of the patients also noted normal activity consistent with consciousness lasting anywhere from 30 minutes to an hour during CPR. 

 Cardiac arrest is a lethal experience for most patients, with the heart-stopping completely and needing to be resuscitated through CPR and an automated external defibrillator (AED). NFL player Damar Hamlin publicly suffered a cardiac arrest on the field during a football game last season and received CPR. “There’s nothing more extreme than cardiac arrest because they’re literally teetering between life and death, they’re in a deep coma, and they don’t respond to us physically at all,” according to lead study author Dr. Sam Parnia, an associate professor in the department of medicine at NYU Langone Health. Regarding the transcendent experiences that patients experienced, Parnia noted, “They may have had a life review, they may have gone to a place that felt like home, and so on.” Some of the most intense experiences are called near-death experiences (NDE), where the patient may report seeing a deceased loved one or having a sense of intense peace. 

Another study in May looked at the brain activity of deceased patients during cardiac arrest. Researchers in that study found an uptick in gamma activities in the brain during cardiac arrest. The resulting gamma activity was similar to that of having dreams, causing researchers to believe the influx of gamma activity might be why some patients report NDEs. Researchers could not interview any of the patients in the study as to what they saw as they passed away due to cardiac arrest. Dr. Katherine Berg, an assistant professor of medicine at Harvard Medical School, wrote in an email that this latest study will help doctors provide better aftercare for CA survivors. “I hope that studies like this one will prompt physicians to ask cardiac arrest survivors about these memories and experiences and assess for any post-traumatic stress or other psychological symptoms that might need to be addressed.”