January 04 : We often read reports about doctors’ dilemma to declare a patient dead, who is in a vegetative state or in coma for a long time. Scientists around the globe have still not come to a consensus on a reliable factor by which they can determine if a person is alive or dead.
If this problem is resolved, it will definitely help doctors to make medical decisions about anesthesia or to treat patients in vegetative state. Currently, doctors rely on electroencephalogram, or EEG, to ascertain the level of consciousness of the brain in patients who are in vegetative state.
Is EEG reliable?
A Michigan medicine team was able to find out that EEG was not too reliable to track if the brain is awake or dead. According to Dinesh Pal, Ph.D., assistant professor of anesthesiology at the U-M Medical School, relying solely on EEG is wrong as it cannot correlate with behaviour. The Michigan team is, therefore, asking people in the medical community to be more cautious when interpreting EEG data.
The researchers have pointed out that in case of a patient under anesthesia, an EEG will display some sort of unconsciousness; reduced brain connectivity; less change in brain activity over time; and increased slow waves, which are also associated with patients in deep sleep, vegetative state and in coma.
What the new study revealed
Dinesh Pal and his team studied the data of a 2018 study to find out what happened when a brain was conscious under anesthesia. The team studied an area of the brain called the medial prefrontal cortex, which helps to make us attentive and conscious. The team used rats to do the test. They applied a drug in that part of the brain that can mimic the activity of neurotransmitter acetylcholine—a chemical released by a nerve cell or neuron. By doing so, the researchers could arouse some of the rats, who moved around despite being given anesthesia. When the same drug was applied at the back of the brain of the rats, who were also given anesthesia, it did not awake them.
The team then studied the EEG data of the rats. They particularly studied those factors that are said to correlate with wakefulness. They were surprised to find that the EEGs of both the groups of rats were same, which means EEG of the moving rats under anesthesia and EEG of the non-moving rats under anesthesia were the same.
This clearly shows that EEG is not a reliable mode to ascertain if a brain is awaken or dead. The study concluded that EEGs cannot always accurately capture the level of consciousness in surgical patients. However, EEG can help to determine the level of unconsciousness during general anesthesia.