The aim of this study was to evaluate the effects of the continuous infusion of ketamine on recovery characteristics after total intravenous anesthesia (TIVA) with propofol.

Fifty-six patients undergoing tympanoplasty were randomly allocated to group I (control, n = 20), group II (ketamine 0.3 µg/ml, n = 16) or group III (ketamine 0.6 µg/ml, n = 20). Ketamine and propofol were continuously administered by using target-controlled infusion (TCI) at different ketamine steady-state concentrations. Blood pressure, heart rate and the time interval from the discontinuation of propofol to eye opening and discharge were measured.

The changes in mean arterial pressure and heart rate before and after auditory ossicles movement examination were larger in group I than in group II or in group III (P <0.05). And, the times to eye opening and to discharge from the recovery room were longer in group II and group III than in group I (P <0.05). Hallucination occurred only in seven patients of group III.

Groups II and III were more stable hemodynamically than group I, but patients in groups II and III required a longer recovery time than group I. No hallucination was found in groups I and II. We conclude that when ketamine is administered in combination with propofol, a lesser concentration than 0.3 µg/ml of ketamine or early discontinuation of ketamine infusion appear to be appropriate.