Remifentanil-propofol vs. sufentanil-propofol: optimal combinations in clinical anesthesia

Two opioid regimens, computer-simulated to provide optimal general anesthesia in combination with propofol, were compared using clinical criteria.

Fifty patients undergoing thyroid surgery were blindly, prospectively and randomly allocated to receive either (a) i.v. remifentanil (1.5 micro g kg-1, followed by 0.2 micro g kg-1 min-1) or (b) i.v. sufentanil (0.2 micro g kg-1 followed by 0.2 micro g kg-1 h-1). Remifentanil infusion was stopped at the last skin suture. Sufentanil infusion was stopped 30 min before the end of surgery. Intravenous propofol was titrated to keep BIS at 50+/-5. Remifentanil and sufentanil groups were compared with regards to (a) propofol delivery, (b) hemodynamic and recovery variables, and (c) effect-site propofol levels during a steady-state period for effect-site remifentanil and sufentanil levels. P<0.05 was significant.

Groups were similar in demographic data; types and durations of surgery; total propofol consumption; and response, extubation and emergence times. During the steady-state period for the opioid delivery, the remifentanil and sufentanil effect-site levels were 5.3 ng ml-1 and 0.18 ng ml-1, respectively (potency ratio=30). In both opioid groups, in accordance with previous computer-simulations, the effect-site propofol concentrations remained (a) within a narrow range unaffected by surgical stimuli, (b) significantly smaller in the remifentanil group than in the sufentanil group, but (c) smaller than expected from previous computer-simulations. More patients required ephedrine following induction of anesthesia in the remifentanil compared with the sufentanil group.

The present clinical trial conducted in thyroid surgery is consistent with previous computer-simulated opioid-propofol combinations with respect to intraoperative and recovery variables. Effect-site propofol ranges were, however, lower than expected.