Pharmacokinetic study of extradural and intrathecal sufentanil anaesthesia for major surgery.

We have studied the plasma concentrations (Cp) and pharmacokinetics of sufentanil injected i.v. (IVS), intradurally (IS) or extradurally (ES) under general anaesthesia in 31 patients undergoing major abdominal surgery. Sufentanil appeared in plasma very rapidly and Cpmax was also attained rapidly after both extradural and intrathecal injection. Apart from the first 2 min after injection, Cp after ES and IVS were comparable until the end of the study. Cp after ES was greater than after IS up to 0.25 h. Cp after IS was significantly greater than that after ES at 1 h and 2.5 h, and was also greater than that after IVS at 3 h. At tracheal extubation there was no difference in Cp between groups. Peak Cp values were significantly different between ES and IS, but the times taken to reach Cpmax were comparable. Plasma pharmacokinetics after ES and IS were similar. The plasma mean residence time and volume of distribution of sufentanil at steady state after ES and IS were significantly different in comparison with those after IVS.