States of Awareness During General Anesthesia

Since 1959 much concern has been aroused by reports of surgical patients being able to recall events occurring during general anesthesia. One major problem is that there are no characteristic physiological parameters to indicate that the patient is aware of what is going on. Contrary to traditional concepts, anesthesia seems to be a personal experience, and from time to time the anesthetist discovers to his dismay that he can play no legitimate part in its direct measurement.