Anaesthesia and intra‐ocular pressure: a comparison of total intravenous anaesthesia using etomidate with conventional inhalation anaesthesia

Abstract

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.

Effects of anesthetic induction with midazolam-propofol and midazolam-etomidate on selected ocular and cardiorespiratory variables in clinically normal dogs

“…The mechanism of action by which etomidate causes a decrease in IOP in both rabbits and humans is unknown, but proposed theories include an increase in facilitation of aqueous outflow and decreases in central venous pressure, SAP, and PaCO 2 . 11,12,27 The effects of all of these physiologic variables are largely mediated by choroidal blood flow. 11,27 The cause of the increase in IOP observed in the present study may be species differences in ocular anatomy or physiologic autoregulation.…”

“…11,12,27 The effects of all of these physiologic variables are largely mediated by choroidal blood flow. 11,27 The cause of the increase in IOP observed in the present study may be species differences in ocular anatomy or physiologic autoregulation. Another possibility is that the increase in IOP is not caused by etomidate itself, but secondary to the ptyalism and vomiting that were associated with the midazolam-etomidate protocol.…”

The Effect of Nitrous Oxide on the Intraocular Pressure in Patients Undergoing Abdominal Surgery under Sevoflurane and Remifentanil Anesthesia

“…Our results demonstrated that N 2 O did not affect IOP during 3 hours in patients under general anesthesia with sevoflurane and remifentanil. However, IOP increased at 3 hours after induction of anesthesia compared with starting point in both patients with and without N 2 O. Intraocular pressure (IOP) is known to changing at perioperative period due to anesthetic maneuvers [3] [17], anesthetic agents [4] [18]- [21], and patient's position [22]- [27] and hemodynamics [28]. Tracheal intubation [29], succinylcholine [5]- [7], inhalational anesthesia [1] [2] [8], and nitrous oxide (N 2 O) [21] may influence IOP.…”

Verhalten des intraokularen Drucks in Intubationsnarkose bei Patienten mit und ohne chronischem Offenwinkelglaukom

“…Die choroidale Perfusion unterliegt jedoch einem erheblichen Einflul3. Es besteht eine Proportionalitat des IOD zum Zentralvenendruck (ZVD) (7,19,20,26,27,48). Dies kann durch vermehrte BlutfUlle der Choroidea (verminderter venöser Abflul3) und reduzierten Kammerwasser-abfluB bei erhöhtem Venendruck erklart werden (18).…”

“…Unter den injizierbaren Hypnotika ist die Drucksenkung bei Etomidat und Propofol im Vergleich zu Barbituraten (z. B. Thiopental) besonders stark ausgeprägt (4,14,15,32,38,48,54).…”