Studies suggest that one or two people in every thousand who undergo general anesthesia experience awareness during the procedure, maybe more in children. The Joint Commission, which inspects hospitals in the US, has made awareness during general anesthesia a “sentinel event.” (If you’re a hospital, a practitioner, or a patient, you definitely want to avoid these). The movie “Awake” and various TV programs have dramatized the issue of awareness.
The victims of awareness tell us the experience can be excruciating. Fortunately, most individuals do not experience physical pain but there is the possibility of later developing debilitating post-traumatic stress disorder. (A study of seven children confirmed to have had awareness found none of them had PTSD or any other troubling psychological problems a year later. This does not establish that PTSD does not occur in children who have had awareness but does suggest that long term problems, at least in children, are far from inevitable).
Can awareness be prevented with brain monitoring technology? An important new NEJM study looks at this.