The effect of target-controlled infusion of low-dose ketamine on heat pain and temporal summation threshold

Abstract

We investigated the heat pain threshold (HPT) and temporal summation threshold (TST) before and after target-controlled infusion (TCI) of ketamine with an effect-site concentration (Ce) of 30 and 60 ng/ml. Healthy young volunteers (n = 20) were enrolled. A thermode was applied to the volar side of each volunteer's right forearm, and HPT and TST were measured before and after TCI of ketamine. Vital signs and psychedelic effects according to ketamine infusion were also observed before and after TCI of ketamine. Mean HPT after TCI of ketamine with a Ce of 30 and 60 ng/ml did not increase significantly. However, mean TST after TCI of ketamine with a Ce of 30 and 60 ng/ml increased significantly, in a dose-dependent fashion, compared with the value before ketamine TCI. Vital signs showed no significant difference before and after ketamine TCI. The visual analog scale score of psychedelic symptoms was higher with a Ce of 60 ng/ml than with 30 ng/ml. TCI of ketamine with a Ce of 30 and 60 ng/ml increased TST but not HPT.