As many as 10 percent of the patients who are brought under full anesthesia remain partially conscious during the operation. That’s according to a study led by Robert Sanders, an anesthesiologist, and neuroscientist at the University of Sydney in Australia.
How does general anesthesia work in relation to certain biological differences, including gender and age? That was the key question of the study, in which 338 adults between 18 and 40 years old participated. Shortly after tracheal intubation in the forearm, subjects were asked to shake hands once if they understood what they were being told, and twice if they experienced pain.
Eleven percent appeared to react after the anesthetic, although they could not remember anything about it afterward. Of that 11 percent, half reported feeling pain (after which the researchers adjusted the anesthetic dose).
Scientists speak of ‘connected or connected consciousness’, in which people are no longer fully conscious, but are still able to perceive stimuli. The study showed that there was less risk of “connected consciousness” if a continuous level of anesthesia was maintained in the minutes after initiation of the anesthetic and before intubation. That’s when a plastic tube is inserted into a person’s trachea to maintain airflow and deliver anesthetic drugs during surgery.
The scientists also found that women are more likely to experience connected consciousness than men: in the women, 13% responded to commands under anesthesia, compared to 6% of the men. In addition, it is also more common in young adults than in older ones. Why is that? The scientists don’t have an answer to that yet. Further research is therefore needed to gain more insight.
Anyone who will soon have to go under the knife and is worried about the anesthetic after reading this article can sleep on both ears, according to Dr. Sanders. “It’s very important to know that patients don’t remember responding to commands,” says Dr. Sanders, and he emphasizes that general anesthesia is generally very safe.