Visual evoked potentials during etomidate administration in humans.

The effects of etomidate on visual evoked potentials (VEP) were studied in 22 patients undergoing gynaecological procedures. They were divided into two groups: the etomidate group (12 patients) and the fentanyl-N2O-etomidate group (ten patients). In the etomidate group, etomidate 0.3 mg.kg-1 was given as a bolus injection during induction of anaesthesia which was followed by an infusion of etomidate 0.05 mg.kg-1.min-1. No significant changes were observed in the amplitudes of P100 or N70. Latencies of the P60, N70, and P100 were slightly increased. In the fentanyl-N2O-etomidate group, a bolus injection of 0.3 mg.kg-1 of etomidate was given during anaesthesia with 3-4 micrograms.kg-1 of fentanyl and 60 per cent nitrous oxide. The amplitude of the P100 was significantly decreased and the latencies of the P60 and N70 were significantly increased. In conclusion, interpretation of the VEP during etomidate administration alone was not hard to perform but, when given together with fentanyl-nitrous oxide anaesthesia, the VEP was affected significantly making its interpretation difficult.