Staying 'Conscious' Under Anesthesia May Be Much More Common Than We Realized

General anesthesia knocks us out and blocks our sense of pain in a matter of seconds before surgery.

Some people who are responsive to their surrounds under general anesthesia can't remember what happened afterwards.

The largest study of its kind to date suggests that connected consciousness is more common than first thought, affecting 1 in 10 young adults and women more than men.

The researchers say that the findings show the need to better understand how different people respond to drugs. Even after 170 years of use, we still don't have a good idea of how general anesthesia works.

There is an urgent need for further research on the biological differences, particularly sex, that may influence sensitivity to anesthetic medication, according to the study author.

If the results of the new study can be duplicated, it will be possible to understand who is more likely to experience consciousness and how connected anesthetists can be.

Estimates had suggested that 5 percent of people going under general anesthesia experienced consciousness. The team suspected that it might have been more common in younger people.

The results of the new study suggest that a larger than expected amount of young adults are still responsive before surgery begins.

The young adults in the study were told to squeeze the researchers hand once if they understood and twice if they were in pain.

After waking up, participants were asked to recall 16 words that they had heard under anesthesia, to see what they remembered.

The study found that women were between two to three times more likely to experience connected consciousness than men.

If a continuous level of anesthesia was maintained in the minutes after anesthesia was injected and before intubation, the chances of connected consciousness were lower.

It is important to note that connected consciousness is different to the awareness that only a small percentage of people experience during anesthesia, after which they can recall specific details about the procedure.

In this instance, "Connected" refers to parts of the brain that are capable of processing sensations but not fully aware.

Patients expect to be unconscious under anesthesia, and this shows why research into anesthesia is important.

13 percent of women in the study responded to commands under anesthesia, compared to only 6 percent of men, even though they received the same weight-adjusted amounts of propofol, a drug used to start and maintain general anesthesia.

The researchers wrote in their paper that there were differences in dosing, but they did not explain why females experienced connected consciousness more often than males.

Half of the 37 people who responded to commands indicated they were in pain, which would have been fixed by adjusting the dose of anesthesia drugs. A person clearly recalled the experience of surgery after it ended.

The paper states that this is a higher level of consciousness than patients anticipate during general anesthesia.

Being in a state of anesthesia only requires a person to be disconnected from their environment, not necessarily involving a full loss of consciousness.

That seems to be a fine line for anesthetists to tread, and one which appears to vary greatly from person to person.

A better understanding of how maintaining continuous anesthesia in the first few minutes may help reduce the incidence of connected consciousness is something that anesthetists might have.

It is important to note that patients did not respond to the commands, and that general anesthesia is very safe.

He says that it was reassuring to see that the risk of connected consciousness was reduced if the drugs were administered continuously.

The British Journal of Anaesthesia published the study.