SummaryIn tra-ocular pressure ( I O P ) The intravenous anaesthetic agent etomidate has been shown to produce a major reduction in 1OP when used as an induction agent.* The use of a total intravenous anaesthetic technique using etomidate was considered therefore, to have potential value in combining pollution-free anaesthesia with possible optimal effects on IOP.This study compared changes in 1OP which occur. under standardised conditions, between conventional inhalational anaesthesia and a technique based on an etomidate infusion.
Paticwt.\ ond method\Ten patients were studied in each group. All patients were ASA I rated and prcscnted for elective ophthalmic surgery; informed consent was obtained in each case. Approval was obtaincd from the Ethical and Standards Committee of the Iiniversity of Natal.Premedicntion in both groups consisted of papaveretum I S mg intramuscularly with diazepam 10 mg orally. administered 1 hour before surgery. Upon arrival at the operating room, a central venous catheter (16 FG) was inserted under local anaesthcsia (l';,; Iignocaine), via the antecubital fossa or right internal jugular vein. Position of the catheter tip was not ascertained radiologically, but oscillation with respiration and free grav-ity reflux of blood was demonstrated in each case. A separate intravenous (i.v.) infusion of Ringer's lactate was commenced at a suitable peripheral site.Thc patient was then placed in a horizontal supine position on the operating table. A control reading of IOP was taken using the Perkins applanation tonometer following the installation of benoxinate 0.2:,,> with fluorescein. Simultaneous readings of systolic arterial ~ *Present appointment: Senior Registrar. Department or Anaesthesia. Royal Infirmary. Bristol BS2 8HW.