Scientists have revived brain activity in pigs for up to nearly an hour after blood circulation stopped. A surprising discovery by Chinese researchers has maintained functionality for hours in some cases.
This result represents a major step forward in research into how to restore brain function after patients suffer sudden cardiac arrest. This suggests that doctors may be able to extend the short window in which they can successfully resuscitate patients after cardiac arrest.
Any tips? The patient’s intact liver (the organ the body uses to purify blood) is incorporated into a life support system used to revive the brain after a period of time.
Sudden cardiac arrest causes many problems for the body due to the rapid cessation of blood flow. The subsequent reduction in circulation to each part of the body is ischemiawhich occurs in the brain and can cause severe irreparable damage within minutes. This is why the resuscitation period from cardiac arrest is so short.
Multiorgan ischemia is known to play a role in the brain’s ability to recover after cardiac arrest, but individual organs have not been well studied.
In recent years, scientists have used pig models to test ways to limit brain damage. Under the supervision of He Xiaochun, a physician at Sun Yat-sen University in China, a team of scientists focused on the animals to understand the role of the liver in brain recovery after ischemia due to cardiac arrest.
The research team used 17 Tibetan minipigs raised in the laboratory to compare the presence and absence of livers in circulatory failure. In one set of experiments, two groups of pigs were exposed to cerebral ischemia for 30 minutes. One group also underwent hepatic ischemia, and the other group did not. On the other hand, no ischemia occurred in the control group.
When the pigs were euthanized and their brains examined, it was clear that the control group had the least amount of brain damage. However, the group that did not undergo liver ischemia had significantly less brain damage than the group that underwent liver ischemia.
The next step in the research was to integrate the intact liver into a life support system that resuscitates completely removed brains from euthanized pigs. Although this is unlikely to be a scenario used in human treatment, it could help scientists understand the period during which resuscitation might be possible.
Basic life support systems included an artificial heart and artificial lungs to help pump fluid to the brain. One group incorporated pig livers into a system known as liver-assisted cerebral normothermic mechanical perfusion.
First, the brain was connected to the life support system 10 minutes after the start of the life support procedure. In the liver-free system, electrical activity in the brain appeared within 30 minutes and then declined over time.
The researchers also experimented with different delays, connecting the brain to the liver support system at intervals of 30, 50, 60, and 240 minutes. The longest interval that showed the most promise was 50 minutes after blood was cut off. The brain resumed electrical activity and remained so for six hours before the experiment was stopped.
Remarkably, in brains that were deprived of oxygen for 60 minutes, activity recovered for only three hours before disappearing. This suggests a critical period for successful resuscitation with the addition of a functioning liver.
The researchers say these results suggest that the liver plays an important role in the progression of brain damage after cardiac arrest. The findings suggest new avenues in brain injury research and could improve survival and recovery outcomes for human patients in the future.
This research EMBO molecular medicine.
