Intraocular pressure during 4-hydroxybutyrate narcosis.

Abstract

4-Hydroxybutyrate (Gamma-OH, Egic) is a hypnotic which can be used to produce unconsciousness by its direct cortical action. It has little medullary depressant effect and no analgesic action. Surgical stimuli must therefore be prevented from reaching the central nervous system by local analgesia. Its use in this way is described in the foregoing article (Smith, Beveridge, and Wyllie, 1972). This paper describes the changes in intraocular pressure during 4-hydroxybutyrate narcosis and compares them with those observed during conventional general anaesthesia.Methods 87 patients undergoing cataract extraction were included in this study. 45 patients were given 4-hydroxybutyrate with local anaesthesia but without endotracheal intubation, and 42 patients were given nitrous oxide and halothane after intubation using suxamethonium. The groups were comparable for age and sex, and the ages ranged from 55 to 83 years (mean 69: S.D. 9.96).The intraocular pressures were measured by a Schiotz tonometer in the eye not prepared for surgery. The Schiotz tonometer was used for its simplicity and degree of accuracy. In a recent comparative trial, pressure readings with the Schiotz tonometer were found to be comparable with those using the Draeger hand-held applanation tonometer (Finlay, 1970). Robertson and Gibson (I968) The pressures were compared in each group of patients. A further subdivision was made for those patients who had received acetazolamide (as 500 mg. Diamox Sustet, Lederle) orally on the previous evening. ResultsThe Figure indicates the pattern of intraocular pressure values in both groups of patients who had not received acetazolamide.