Effects of remifentanil on propofol requirements for loss of consciousness in target-controlled infusion.
BACKGROUND
We evaluated the effects of various doses of target-controlled remifentanil on the propofol requirements for the loss of consciousness (LOC) and the consequent hemodynamic changes on the induction of intravenous anesthesia in day-case surgery.


METHODS
Eighty infertile female patients scheduled for diagnostic laparoscopy were randomly allocated to 1 of 4 groups (20 in each) to receive a target concentration of 1 ng x mL(-1) (Remi-1 group), 2 ng x mL(-1) (Remi-2 group), 3 ng x mL(-1) (Remi-3 group), or 4 ng x mL(-1) remifentanil (Remi-4 group). After equilibrium of remifentanil, propofol was administered with initial target concentration of 2 microg x mL(-1) and with 1 microg x mL(-1) increments. The response to call was assessed every 15 s until a LOC was achieved.


RESULTS
The effect site concentration of propofol (Ce), the total propofol dose, and the time for LOC were significantly decreased with increasing remifentanil concentrations. There was a moderate correlation between the effect of remifentanil and the effect site concentration of propofol at the LOC (r(2) = 0.353, P < 0.05). There was also a moderate correlation between the remifentanil concentration and the time to LOC (r(2) = 0.442, P < 0.05). There were no significant differences in the hemodynamics among the groups, although the decreases in blood pressure after propofol administration in all groups were significant compared with baseline.


CONCLUSIONS
The effect of altering the target-controlled remifentanil concentration during propofol induction was found to be dose-dependent. There was no significant difference in the cardiovascular response with the studied range of concentrations of remifentanil and propofol.
Jee
Y S
YS
Department of Anesthesiology and Pain Medicine, Cheil General Hospital and Women's Health Center, Kwandong University School of Medicine, Seoul, Korea.
Hong
J Y
JY
D000328:Adult; D018686:Anesthetics, Intravenous / Q000008:administration & dosage*; D016292:Procedural Sedation; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D006993:Hypnotics and Sedatives / Q000008:administration & dosage*; D007262:Infusions, Intravenous; D010535:Laparoscopy; D008875:Middle Aged; D010880:Piperidines / Q000008:administration & dosage*; D015742:Propofol / Q000008:administration & dosage*; D000077208:Remifentanil
D018686:Anesthetics, Intravenous; D006993:Hypnotics and Sedatives; D010880:Piperidines; D000077208:Remifentanil; D015742:Propofol