What kind of people wake up during anesthesia and how to predict it

Brain structures that can predict a person's predisposition to accidental awareness under anesthesia have been identified for the first time at Trinity College Dublin.

The results may help identify people who may need above-average doses of anesthetics. Although anesthesia has been used in clinical medicine for more than 150 years, scientists don't fully understand why its effects on people are so varied.

One in four patients supposedly unconscious during general anesthesia can actually have subjective experiences such as dreams, and in very rare cases (0.05-0.2%) people accidentally "wake up" during a medical procedure. The new study involved 17 healthy people who were injected with the most common clinical anesthetic.

The participants' reaction time to the detection of a simple sound was measured when they were awake and when they were under sedation. The brain activity of 25 participants was also measured when they listened to a simple story in both states.

As it turned out, participants who were resistant to anesthesia had fundamental differences in the function and structures of the frontal-parietal brain regions. It is important to note that these brain differences can be detected in advance. People with more gray matter in frontal areas and stronger functional connectivity in frontoparietal brain networks may require higher doses of anesthetic during surgical interventions, the researchers claim.

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