Induction of general anaesthesia by effect‐site target‐controlled infusion of propofol: influence of pharmacokinetic model and ke0 value

We studied the use of a new k_e0 value (0.6 min^?1) for the Marsh pharmacokinetic model for propofol. Speed of induction and side‐effects produced were compared with three other target‐controlled infusion systems. Eighty patients of ASA physical status 1–2 were studied in four groups in a prospective, randomised study. Median (IQR [range]) induction times were shorter with the Marsh model in effect‐site control mode with a k_e0 of either 0.6 min^?1 (81 (61–101 [49–302])s, p < 0.01), or 1.2 min^?1 (78 (68–208 [51–325])s, p < 0.05), than with the Marsh model in blood concentration control (132 (90–246 [57–435])). The Schnider model in effect‐site control produced induction times that were longer (298 (282–398 [58–513])s) than those observed with the Marsh model in blood control (p < 0.05), or either effect‐site control mode (p < 0.001). There were no differences in the magnitude of blood pressure changes or frequency of apnoea between groups.