T. Cecil Gray

Role of Apnoea in Anaesthesia for Major Surgery

There has been widespread support for the concept which views anaesthesia as a triad (Rees and Gray, 1950), the components of which, narcosis, relaxation,and analgesia, ideally are produced by specific drugs with selective actions. It is now a generally used method of anaesthesia to induce sleep with thiopentone, to produce muscular relaxation with a relaxant drug, and to reduce the response of the patient to noxious stimuli by the use of nitrous oxide and occasionally a more potent specific analgesic drug such as pethidine. During the past six years an anaesthetic technique based on this principle has been adopted by us. Thiopentone has been used in minimal doses to produce sleep, a 50% mixture of nitrous oxide and oxygen, if necessary supplemented by pethidine (or, in the earlier years, very minimal dos.s of ether), to produce analgesia, and a paralysant drug to attain relaxation and initiate the control of respiration. As a result of the respiratory depression subsequent upon adequate doses of the relaxant agents, there has been no-hesitation in resorting to completely controlled respiration for the cases in which this technique has been employed. The experience gained during this period led to the conolusion that use of controlled respiration reduced the dose of both relaxant and thiopentone which it was necessary to administer in these cases. The examination and significance of this possibility are the subject of this paper.

d-Tubocurarine in Caesarean Section

at each of them and no correlation between the storage temperature and the number of cases could be made out. The butcher who was the source of the staphylococcus causing the outbreak had local treatment for the lesion in his hand, which soon healed. He also had a course of sulphathiazole, and swabs from his nose, throat, and hand are now negative. This experience has shown the value and importance in such outbreaks of close liaison between all interested parties and the necessity for thorough and prompt investigation by a bacteriologist with up-to-date services at his disposal.

A REVIEW OF LOCAL ANÆSTHETICS

THE investigation of compounds possessing local ansesthetic activity has been in progress since 1884 when Kollerl observed that a solution of cocaine when applied locally caused ansesthesia of the cornea. Cocaine was soon used to produce nerve block, infiltration and spinal ansesthesia. After it had been in use for 6 years, Folk2 in 1890 reported 176 cases of acute intoxication, of which 10 were fatal. Einhorn3 introduced the less toxic procaine (novocain) in 1904 and by so doing began the modern era. Procaine is still regarded as the safest and probably the most satisfactory all-round local ansesthetic. It is the purpose of this review (A) to discuss the mode of action of local ansesthetics and the molecular configurations responsible for their activity, (B) to consider their absorption and elimination, and other factors influencing their toxicity, and (C) briefly to describe some of the newer drugs which have been synthesized in an attempt to approach an apparently unattainable ideal.

An investigation of the synergisms between d-tubocurarine chloride and thiopentone.

THE alkaloid d-tubocurarine chloride is now extensively used in anasthesia to produce muscular relaxation. It has been believed by anasthetists that this substance has some central action and potentiates the narcotic effects of the anaesthetic agents, quite apart from its relaxant and paralysant properties. This clinical impression was regarded4 as an added advantage of the use of this substance. It seemed, however, desirable to investigate further this alleged action. With this in view, 24 experiments were carried out on two volunteers. In these an attempt was made to measure the period of narcosis following, on the one hand, a dose of thiopentone, and on the other hand, a dose of d-tubocurarine chloride followed by thiopen tone. Experimental Procedure The experiments were performed at weekly intervals at the same hour on the same day of the week, under conditions as nearly controlled as possible. If either of the subjects reported having had an unduly fatiguing day on the day before the experiment, or a late or disturbed night before the experiment, the experiment was postponed for that week. The injections were given intravenously at the same rate and at the same timed intervals. Atropine gr. 1/100 (0.65 mg.) dissolved in 2 c.cm. of sterile distilled water was followed immediately by a test dose of 5 mg. of d-tubocurarine chloride. The test dose is given by anresthetists to foresee the possibility of hypersensitivity in their patients, and it was thought preferable to follow this clinical procedure. After two minutes a further 10 mg. was injected and followed at once by 0.5 gm. of thiopentone in 5 % solution. The latter injection was given over 40 seconds. On every alternate week the injections of d-tubocurarine chloride were omitted. In order to estimate the subject’s return to consciousness the following four tests were made at one minute intervals after the completion of the thiopentone injection. (1) Supra-orbital pressure: firm pressure with the thumb was exerted on the supra-orbital margin. A response to this painful stimulus was always the first evidence of lightening anasthesia and usually was present one to two minutes after the end of the injection. There was no appreciable statistical difference in the time of this return whether or not d-tubocurarine chloride was injected (Tables I and 11). The following method was employed in every instance.