Effects of different target effect-site concentrations of remifentanil on the sedative effect of propofol

Objective To investigate the effects of different target effect-site concentrations (Ces) of remifentanil on the sedative effect of propofol. Methods Fifty ASA Ⅰ or Ⅱ patients aged 20-55 yr weighing 48-86 kg with body mass index ＜ 30 kg/m2 were randomly divided into 5 groups ( n = 10 each) . Anesthesia was induced with TCI of remifentanil (Ce = 0, 2, 4, 6 and 8 ng/ml in groups R0-R4 respectively) and propofol. The initial Ce of propofol was 2.0 μg/ml in the 5 groups, and then the Ce of propofol increased by 0.5 μg/ml every 1 min until BIS value decreased to 50. BIS value and Ce of propofol were recorded as the patient lost consciousness. The effect-site concentration and consumption of propofol and the time required were recorded when BIS value decreased to 50.Results BIS value was significantly increased, while the effect-site concentration of propofol was significantly decreased as the patient lost consciousness, and the effect-site concentration and consumption of propofol were significantly decreased and the time required was shortened when BIS value decreased to 50 in R2-R4 groups compared with group R0 (P ＜ 0.05 or 0.01) . Conclusion The sedative effect of propofol can be enhanced when the Ce of remifentanil reaches 4 ng/ml, and the effects are comparable when the Ce of remifentanil reaches 4, 6 and 8 ng/ml. Key words: Piperidines;  Propofol;  Conscious sedation;  Drug delivery system