This study was designed to evaluate the effects of the continuous infusion of ketamine on the cardiovascular system, patient recovery, and the postoperative analgesic effect of total intravenous anesthesia (TIVA) with propofol.

Forty-one patients undergoing tympanoplasty were randomly allocated to a control (no ketamine, n = 12), or to K1 (ketamine 0.1 µg/ml, n = 16) or K2 groups (ketamine 0.2 µg/ml, n = 13). Ketamine and propofol were continuously administerd by target controlled infusion (TCI) at different ketamine steady-state concentrations. The severity of injection pain was assessed and hemodynamic responses were measured before and after intubation and skin incision, respectively. Respective times lapsed from the discontinuation of propofol to eye opening, hand grasp, and extubation were measured, and the concentration of propofol and ketamine were determined at the time of extubation. Visual analogue scale (VAS) for postoperative pain, postanesthesia recovery score (PARS) and post-operative complications were also evaluated in the recovery room.

No statistical differences were identified with respect to severity of injection pain, hemodynamic response, VAS or PARS among the groups. But the respective times lapsed to extubation, eye opening and hand grasp after the discontinuation of propofol were longer in group K2 than in the other groups (P < 0.05), and the respective concentrations of propofol at the time of extubation, eye opening, and hand grasp were lower in group K2 than in the other groups (P < 0.05). No complications (hallucinations, delirium) occurred in any group in the recovery room.

The target plasma concentrations of ketamine used in this study (0.1 µg/ml, 0.2 µg/ml) appeared inadequate to maintain hemodynamic stability and the postoperative analgesic effect, and to prevent delayed emergence.