Flatlining but not dead: Why we need new CPR approaches during cardiac arrest

Emergency medicine and resuscitation experts say that signs of electrical recovery in the brain for as long as an hour into ongoing cardiopulmonary resuscitation underline the importance of prolonged CPR—and of devices that measure the quality of CPR."If people who go into cardiac arrest receive good quality chest compressions that restore blood flow to the brain, then consciousness is restored as well," Dr. Jasmeet Soar, an anesthetics and intensive care medicine specialist in Bristol, U.K., and editor of the journal Resuscitation, said in an interview with Medscape Cardiology. "We know that because if chest compressions are stopped, the person becomes unconscious again. This CPR-induced consciousness has become more common when professionals do the CPR because resuscitation guidelines now place a much bigger focus on high-quality CPR—'push hard, push fast.”Dr. Soar pointed to two types of brain activity that might occur when CPR is done effectively: CPR-induced consciousness—usually indicated by signs such as combativeness, groaning and eye-opening—or a perception of feeling lucid and having memories from the period of cardiac arrest."Patients who experience this may form memories that they can recall,” explained Dr. Soar. “We're not sure whether that happens during CPR or while the patient is waking up during intensive care, or how the brain creates these memories, or if they're real memories or coincidental, but it's clear the brain does form them during the dying and recovery process."Dr. Sam Parnia, director of critical care and resuscitation research at NYU Langone Health—which operates academic medical centres in New York—emphasized the importance of sustained CPR following a cardiac arrest."People are giving up too soon on trying to revive individuals, and they should be trying more modern strategies, such as extracorporeal membrane oxygenation," he said.Dr. Parnia's recent research showed that while the brain may not be functioning in the first few minutes of cardiac arrest, it isn’t dead and brain activity can be restored up to an hour later with proper resuscitation.The 2023 study, which looked at 567 in-hospital cardiac arrest patients in the United States and United Kingdom and interviewed 28 survivors, found that close to one-third had memories or perceptions that suggested consciousness during their cardiac arrest.The study authors organized these reported memories or perceptions into four groups: recalled experiences of death, memories from when the patient emerged from coma during CPR, emergence from coma after CPR, and dreams or dream-like experiences."Many people label recalled experiences of death as 'near-death' experiences, but they're not," said Dr. Parnia. "Medically speaking, being near to death means your heart is about to stop. But the whole point is that these people are not near death. They actually died and came back from it."Dr. Parnia’s study used EEG monitoring in a subset of patients and found that among those with evaluable EEG data, brain activity returned to normal or near-normal after flatlining in about 40% of images. Spikes were seen, in varying degrees, in the delta, theta, alpha and beta waves associated with higher mental function."Incredibly, we found that even though the brain flatlines, which is what we expect when the heart stops, with professionally given CPR even up to about an hour after this, the brainwaves changed into normal to near-normal patterns," Parnia said. "Although the brain stops working when it flatlines, it does not die within five or 10 minutes of oxygen deprivation."Read: 'Significantly higher' than previous estimates: New analysis of out-of-hospital cardiac arrests adds tens of thousands to yearly totalThe first step in effective intervention during a cardiac arrest is to increase blood flow with quality CPR and then measure whether the resuscitation is working, said Dr. Lance B. Becker, professor and chair of the department of emergency medicine at the Zucker School of Medicine in Hempstead, N.Y. These measurements can be taken in a number of ways, including with ultrasound devices that gauge blood flow generated during CPR or with compression devices placed between the patient’s chest and the rescuer’s hands to measure the rate and depth of compression. There are also devices that measure blood pressure during CPR.But these devices are rarely used, said Dr. Becker, who is working to design better devices for CPR quality measurement."An example would be a little probe that you could pop on the neck that would study blood flow to the brain with ultrasound, so that while you were pumping on the person, you could see if you're making them better or not," he explained. "We also have some preliminary data showing that the American Heart Association recommended position on the chest (the lower half of the sternum) for doing CPR is not the perfect place for everybody," he said.”At the 2023 American College of Emergency Physicians meeting, Dr. Becker and his team presented data on 175 video-recorded adult cardiac arrests that involved at least one change of compression location and a total of 29 location changes.The data showed a resumption of spontaneous circulation in 41% of CPR where the compression location was adjusted. For about one-third of patients, said Dr. Becker, repositioning of hands during CPR is needed.Read: Can't stand the Bee Gees? These alternative tracks can help optimize CPR"This is not anything that is taught to the public because you can only figure it out if you have some kind of sensor that will let you know how you're doing,” he added. “That's very achievable. We could have that in the future on every ambulance and even in people's homes."Putting certain patients on extracorporeal membrane oxygenation can also improve cardiac arrest survival rates—perhaps by 10%-to-50%—if done properly, said Dr. Becker.Dr. Parnia at NYU Langone Health said he hopes his study’s findings will encourage the development of new treatments or approaches to restart the heart or prevent brain injury."One of my bugbears is that our survival outcomes from cardiac arrest resuscitation have not changed very much for 60 years because we haven't developed new treatments and innovative methods," he said. "Unlike the rest of medicine, we're living in the past."With the work he’s done, “we've opened up the window to developing cocktails of drugs that could be given to patients who have technically gone through death to bring them back to life again," he added.Read: Calgary researchers develop new tool to diagnose genetic mutations within hours

Flatlining but not dead: Why we need new CPR approaches during cardiac arrest

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