Effect Site Concentration using Bispectral Index onInduction of Anaesthesia with TCI Propofol

A Hay R Chapman N Sutcliffe

Department of Anaesthesia, Golden Jubilee National Hospital, Clydebank G81 4HX

Aim:

To examine whether the ‘Marsh’ or ‘Schnider’ pharmacokinetic model^{1 2} most accurately predicts effect site concentration during induction with TCI Propofol.

Methods

Informed consent was obtained from 20 unpremedicated patients. Induction was with TCI Propofol (Schnider, effect site control, target of 4micg/ml). Bispectral Index (BIS, averaged over 15 seconds) was measured every 30 seconds for 10 mins. For all patients the effect site concentration predicted by the Schnider and Marsh models were calculated using the ‘TIVA Trainer’ computer program.

Results

The upper figure shows the BIS results for the 20 patients (expressed as medians and interquartile range). The lower Figure shows the effect site concentration predicted by the 2 models for the 20 patients (expressed as medians).

Conclusion

BIS changes measured during induction of anesthesia with TCI Propofol mirror the change in effect site concentration predicted by the Marsh model.

References:

1 Marsh B, White M, Morton N, Kenny GN. Pharmacokinetic model driven infusion of propofol in children. British Journal of Anaesthesia 1991;67(1)41-48

2 Schnider TW, Minto CF, Shafer SL et al. The Influence of Age on Propofol Pharmacodynamics Anaesthesiology 1999;90(6):1502-1516