Comparison of target controlled infusion and total intravenous anaesthesia with propofol and remifentanil for lumbar microdiscectomy.

Background: Propofol is often combined with remifentanil for induction and maintenance of total intravenous anaesthesia. Target-controlled infusion (TCI) permits adapting infusion to pharmacokinetic models. In this study we compared depth of anaesthesia, haemodynamic variables and times to recovery in patients scheduled for lumbar microdiscectomy and receiving either manually controlled (group I) or target- controlled (group II) infusion of propofol and remifentanil for anaesthesia.

Methods: Twenty three patients (group I) received a bolus induction of propofol 2 mg kg(-1) and remifentanil 1 μg kg(-1). Twenty five patients (group II) received propofol and remifentanil at an initial effect site concentration of 4 μg mL(1) and 4 ng mL(-1) respectively. According to BIS and haemodynamics, propofol/remifentanil infusion rates (group I) or concentration of propofol/remifentanil at an effect-site were adjusted upwards or downwards. We monitored bispectral index (BIS), mean arterial pressure (MAP) and heart rate (HR) during subsequent stages of anaesthesia and operation (T1-T10).

Results: Induction and total doses of propofol and remifentanil, times to recovery were comparable in both groups. BIS was lower at T2-T10 in comparison to baseline values. At T4 and T5 BIS was lower in group II than in group I. In group I, mean HR values were lower at T7-T9 in comparison to baseline values. In exeption of MAP at T6 in group II, MAP was lower at T2-T9 in comparison to baseline values in both groups.

Conclusion: There are no clinically important differences in haemodynamic variables, depth of anaesthesia, time to recovery and doses of propofol/remifentanil between manually controlled and target-controlled infusion of propofol and remifentanil.