Psychomimetic reactions after low-dose ketamine infusion. Comparison with neuroleptanaesthesia.

Low-dose ketamine anaesthesia was compared with neuroleptanaesthesia, in respect of immediate and longer-term psychomimetic reactions, in 40 female patients undergoing elective gynaecological surgery. Qualitatively, but not quantitatively, different psychomimetic reactions occurred in both groups. In the neurolept group the predominant complaint was of a dissociative nature, reported after 24 h by 11 (55%) of the patients, while in the ketamine group the predominant experience was dreaming, reported by eight (40%) of the patients after 24 h. Interviews after 3 months revealed a low frequency of psychomimetic reactions in both groups. However, 30% of all the patients (12) complained of impairment of intellectual function, and in seven patients this was severe enough to interfere with their ability to work.