Haemodynamics during remifentanil induction by high plasma or effect-site target controlled infusion

During total intravenous anaesthesia, the target controlled infusion concentration of remifentanil can be achieved either in limiting maximum plasma concentration (Cp) to the effect site target concentration which corresponds to a plasma TCI technique (pTCI) or as fast as possible to achieve the effect-site target without limiting Cp (eTCI). The aim of this study was to compare the haemodynamic effects of remifentanil pTCI and eTCI during induction of anaesthesia in ASA III patients undergoing cardiac surgery.

28 ASA III patients, scheduled for cardiac surgery, were randomized in two groups: Group pTCI received remifentanil to achieve an effect-site target of 15 ng ml(-1) by limiting Cp to 15 ng ml(-1) and group eTCI received remifentanil to achieve an effect-site target of 15 ng ml(-1) without limiting remifentanil Cp. Before induction, all patients received 30 microg kg(-1) of midazolam intravenously and 2 ml kg(-1) of a gelatin solution. Heart rate, invasive arterial pressure and bispectral index were continuously measured. Differences from baseline values were compared between the two groups using a Mann-Whitney U test. Baseline population characteristics were compared using an analysis of variance.

There were no significant differences in haemodynamic parameters between the two groups. In the group pTCI final effect-site concentration was reached in 7.3 +/- 1.4 minutes and in the group eTCI in 2.2 +/- 0.2 minutes (p < 0.05).

In ASA III patients scheduled for elective cardiac surgery, remifentanil eTCI can be preferred to remifentanil pTCI for induction because of its shorter onset with the same haemodynamic stability.