Anesthesia Induction with Propofol Using a Target Controlled Infusion (TCI)

Background : Target Controlled Infusion(TCI) is designed to achieve a predicted target blood concentration based on population pharmacokinetics and it provides the closest approximation for any individual patients. This study determined which target is appropriate for propofol induction using a TCI in korean adullt patients premedicated with midazolam. Methods : Sixty six patients(ASA I or II, 18∼55 years) premedicated with midazolam were allocated randomly to receive an infusion to achieve and maintain a target blood concentration of 3, 4, 5 and 6 g/ml using a TCI. Induction time was measured as the interval from the start of the infusion to loss of verbal contact and induction within 3 min was considered as successful. Calculated concentration, induction dose, context sensitive decrement time, vital signs, pain score and side effects were checked and compared each other during induction period. Results : The success rate when the target was 3 g/ml was 25%, 58.8%, 77.8% and 100% when targets were 4 g/ml, 5 g/ml and 6 g/ml respectively. EC50 for induction was 3.87 g/ml and EC95 was 5.71 g/ml. Calculated concentration, induction dose, context sensitive decrement time in 3, 4, 5 g/ml group showed no differences among groups, but 6 g/ml group showed statistically significant differences compared with other groups. Vital signs, pain score and side effects showed no differences among groups. Conclusions : Target concentration of 5∼6 g/ml would successfully induce anesthesia in the majority of patients premedicated with midazolam without major hemodynamic changes. (Korean J Anesthesiol 1998; 34: 944∼950)