Sufentanil for balanced anaesthesia: rational dosing scheme is improved bypredicting the concentrations.

During balanced anaesthesia sufentanil may be difficult to use, as the requ ired doses change over time depending on the patient and the noxious stimul i. Patient adjustment may be improved by using pharmacokinetic simulations that predict the concentration achieved in the body. In the first case repo rt, sufentanil was given manually as repeated boluses, then by infusion. As haemodynamic: status remained unstable, a simulation of the sufentanil con centration time course was started during the case. It showed that instabil ity had pharmacokinetic explanation and allowed to determine the adequate s ufentanil concentrations (0.30-0.40 ng.mL(-1) + N2O + isoflurane 0.8-1 vol% for abdominal surgery). However, adjusting the doses manually required num erous human actions. In the second case, sufentanil was given as a computer -controlled infusion. The adequate concentrations were determined (0.15-0.2 0 ng.ml(-1) + N2O + isoflurane 0.4 vol% for peripheral surgery in an aged c ardiac patient). They were maintained with a limited number of human action s and resulted in satisfactory haemodynamic stability. (C) 1999 Elsevier, P aris.