About 4 in 10 people who survive resuscitation after a cardiac arrest seem to have had some kind of awareness during the process, perhaps due to blood returning to the brain 鈥� and this might be why people sometimes report strange visions afterwards, known as near-death experiences.
As a result, some doctors now say that people having cardiopulmonary resuscitation (CPR) may need to be given sedative drugs, to avoid any pain or distress.
Some people who survive CPR report semi-mystical experiences, such as feeling like they are moving down a tunnel towards a light, meeting deceased relatives and even floating above their bodies looking down at the scene. 鈥淭here are common themes,鈥� says at University Hospital Southampton in the UK.
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To investigate, Deakin鈥檚 team recruited staff at 25 hospitals in the UK and US to study people who had a cardiac arrest in hospital and underwent CPR. The process, which can go on for half an hour or more, can include procedures such as chest compressions, artificial ventilation and electric shocks to restart the heart.
As the usual care team worked on the individual having a cardiac arrest, one of the researchers placed headphones on the person鈥檚 ears to play them recordings. A small display screen was also placed above the patient鈥檚 head, showing images that faced the room鈥檚 ceiling 鈥� to see if it is, in fact, possible for people to somehow look down on the scene from outside their body.
People also had various forms of extra monitoring, such as electrodes placed on their head to record brain activity. Those who survived the cardiac arrest were questioned afterwards about any memories.
The team managed to carry out the procedure on 567 people who had a cardiac arrest. About 9 per cent of them survived and 28 of this group were able to be interviewed afterwards. Of these, 11 reported some kind of memory of the events or perceptions suggesting consciousness, giving an awareness rate of 39 per cent.
One insight came from the brain activity monitoring, which revealed that even after 40 minutes of CPR, some of the people had brainwaves that appeared nearly normal.
This could be because chest compressions start returning blood to the brain, says Deakin. 鈥淚t has been assumed that where patients are in cardiac arrest there is no brain activity,鈥� he says. 鈥淐learly awareness is more common than we thought.鈥�
Some people reported what seemed to be clear memories, such as when they were being electrically shocked, as well as dream-like experiences after the resuscitation.
Six people鈥檚 memories were classed as 鈥渢ranscendent鈥� in some way. For instance, one person thought they heard their dead grandmother saying: 鈥淵ou need to go back.鈥� Another person felt they were standing next to the bed, rather than lying on it.
None of the 28 survivors who were interviewed could identify the image on the display screen that had been facing the ceiling. However, one person did identify the words that had been playing through the headphones.
Three words 鈥� apple, banana, pear 鈥� were played five times. The patients were asked to state the names of any three fruits they thought had been said. One person correctly named all three. They could, however, have guessed the fruits by chance, acknowledges Deakin.
The rate of awareness during CPR could be lower in people who don鈥檛 survive the process, because those who are successfully resuscitated would probably have had higher blood flow to their brain, says Deakin. 鈥淲e don鈥檛 know what people who haven鈥檛 survived experienced,鈥� he says.
, an emergency medicine consultant in the UK, says the findings suggest doctors should give more consideration to sedating people undergoing CPR.
People are currently sedated only if they show signs of awareness, such as moving or groaning, which is estimated to happen in about 1 in 100 cases. 鈥淭his should be a trigger to make us [think]: 鈥楽hould we routinely sedate during CPR?鈥�,鈥� she says.
But at the Royal Berkshire Hospital in Reading, UK, says sedatives could lower a person鈥檚 chances of being resuscitated. 鈥淚 don鈥檛 know that there鈥檚 enough science yet to make definite recommendations,鈥� he says.
Dykes says the study also highlights the need for doctors to discuss 鈥渄o not resuscitate鈥� plans with people who wouldn鈥檛 benefit from CPR as their survival chances are so low. 鈥淭he idea of someone being aware during a resuscitation attempt that is futile is horrific,鈥� she says.
Resuscitation
Article amended on 3 August 2023
This article has been changed to correct the number of people whose brainwaves appeared nearly normal after 40 minutes of CPR.
