Ketamine, 2-(0-chlorophenyl)-2-(methylamino)-cyclohexanone, is a general anesthetic which on awakening produces psychic disturbance correlated with the metabolism of serotonin.

Since it is know that acupuncture increases cerebral serotonin, the blood levels of total and free tryptophan, its precursor, were studied in healthy volunteers to find out if the anti-hallucinatory action of acupuncture is dependent on an increase in cerebral serotonin.

The Authors have investigated the antihallucinogenic and sedative effects of auricular points R and shen menn during surgery under ketamine anesthesia.

The results demonstrate that the insertion of the needle in point R is very efficient in reducing hallucinations of ketamine emergence, while the insertion of needle in auricular point shen menn causes only a brief period of sedation in the beginning of the emergence period.

The acupunctural technique employed by the Authors has been shown to increase considerably approbation of ketamine anesthesia.