[Psychedelic effects of subanesthetic doses of ketamine].

Objective: To study the psychedelic effects in healthy volunteers when given subanesthetic dose of ketamine.

Methods: Thirteen male healthy volunteers aged 24-39 years were enrolled. All subjects received subanesthetic doses of ketamine using target control infusion. A stepwise series of target plasma concentrations (0, 100, 200, and 300 ng/ml) were maintained for 20 minutes each. Visual analogue scale (VAS) of mechanical pain by von Frey hair was evaluated, and then the volunteers completed a VAS rating of 13 symptom scales. Pictures were shown to them at the same time. Heart rate, mean blood pressure, and SpO2 were monitored throughout the infusion.

Results: During the process of analgesia, ketamine produced dose-related analgesic effects. With the increase of ketamine dose, some psychedelic effects became more obvious and the memory impairment became worse stepwisely.

Conclusion: Target control infusion of subanesthetic doses of ketamine produce obvious psychedelic effects in healthy volunteers.