Comparison of Ketamine and Thiopental in Healthy Volunteers

The purpose of this study was to compare the psychological effects of ketamine and thiopental anesthesia. In a double-blind comparison, 20 normal female volunteers were given 2.5 mg/kg ketamine intravenously and 20 were given 5.0 mg/kg thiopental intravenously. Subjects were assessed with a variety of objective and subjective psychological measures before, immediately after, and 24 hr, 2 weeks, and 4 months after anesthesia. Immediately after anesthesia, there was a significantly greater incidence of abnormalities of mental status in subjects given ketamine than in those who had received thiopental. Changes were generally short-lived and were no longer evident on the following day. No significant differences were found between the two groups with regard to long-term changes in personality. Changes in mental status are attributed to the slower, more uneven return to consciousness of the subjects receiving ketamine.