4-Hydroxybutyrate narcosis for ophthalmic surgery.

Abstract

4-Hydroxybutyrate (Gamma-OH, Egic) was introduced into anaesthetic practice by Laborit, Buchard, Laborit, Kind, and Weber (i960) in France. It has been used extensively in America and Europe as a hypnotic. Its use in anaesthesia in Great Britain was discussed at a symposium at the Royal Society of Medicine (Gamma Hydroxybutyric Acid, I968), and further information in the British literature is provided by Robertson (I967) and Tunstall (i968a). It seemed to us that 4-hydroxybutyrate could be used to produce a light level of unconsciousness for patients undergoing ocular surgery with local anaesthesia. Preliminary studies were carried out on patients undergoing extraocular operations to assess its suitability for intraocular procedures. The technique was found to be satisfactory and this paper describes its use to maintain unconsciousness in a series of patients undergoing ophthalmic surgery. The results are compared with those from another series who were given a conventional general anaesthetic similar to that described by Kaufman (i 967). The changes in intraocular pressure are described elsewhere (Wyllie, Beveridge, and Smith, I972). Pharmacology 4-Hydroxybutyrate is the sodium salt of gamma-hydroxybutyric acid. It is a basal hypnotic which acts on the cerebral cortex directly with no subcortical action, and therefore has no analgesic properties. An analgesic supplement, however, depresses reflex activity and allows the dose of 4-hydroxybutyrate to be reduced from 70 to 40 mg./kg., as recommended by Tunstall (I 968b). There is bradycardia and a slight fall in cardiac output which can be reversed by atropine (Virtue, Lund, Beckwitt, and Vogel, I966). Surgical stimuli may cause hypertension, tachycardia, and a rise in cardiac output. These reactions can be prevented by a phenothiazine, e.g. perphenazine, which depresses the reticular activating system (Vickers, I968). A short-acting barbiturate, e.g. methohexitone, hastens induction and also eliminates the clonic movements which are an occasional accompaniment of 4-hydroxybutyrate narcosis.Methods 339 patients were studied in this series, of which 64 per cent. were women. i68 patients received 4-hydroxybutyrate and I7I had conventional general anaesthesia. The groups were comparable for age and sex. The ages ranged from 27 to 92 years (mean 68: S.D. I I 5). All patients were assessed preoperatively as fit for anaesthesia. 27 patients had diabetes mellitus and three suffered from myotonic dystrophy. There was the usual high incidence of cardiovascular and respiratory disease associated with elderly ophthalmic patients.

Normocapnic anaesthesia for intraocular surgery.

“…This question has engaged the attention of anaesthetists for many years without a completely satisfactory solution, as shown by the wealth of papers claiming superiority for various techniques (Ives, 1959;Burn and Knight, 1969;Jones et al, 1969;Smith et al, 1972;Delilkan and Chandran, 1972;Lynch et al, 1974).…”

Intraocular pressure during 4-hydroxybutyrate narcosis.

“…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.…”