FoR ~ANY YEARS anaesthetists have felt the need for a non-explosive anaesthetic agent possessing none of the. disadvantages assocmted with chloroform, trichlorethylene and mtrous o~ide, rhat is, the agent should be non-hepatotoxm, stable in the presence of soda lime and heat, an~ have a high therapeu :ie ratio. Since most heavily fluorinated hydrocarbons are not m2qamma)le, and many possess anaesthetic properties,, they present interesting pos,,ibilities. Robbins (1) found that some hydrocarbons had greater therapeutic rati.os than chloroform or ether, but that when they were used, severe hypotension, cardiac arrhythmias and slamulation of skeletal mtlscle occurred. In 1956, Rav ent6s and Suckhng synthesized and investigated a series of fluorinated hydrocarbons, and one in particular-CF8 CHC [Br (Fluothane)-was found to have potent anaesthetic properties (2). The first clinical trial has been reported by Johnstone (8)_who studied the human cardiovascular response to Fluqthane| PH-YSmAL I~OPFmTmS Fluothane| is a clear colourless liquid wath a rather pleasant odour. It has a specific gravity of 1 86 at 20 ~ C. and a bolhng point of 50.2. ~ C. Vapour pressur~ at 20 ~ C. is 248 rnm. Hg. Off/water solubility is 880 compared to 100 for chlo{oform and 8~2 for ether. When exposed to hght, Fluothane decomposes slowly, forming volatile acids. This can be prevented by storing it in amber-coloured bottles or by adding thymol 0.01 per cent W/W. Fluothane is non-infammable, non-explosive and stable in the presence of soda hme. Fluothane should not be confused with Fluomar| (trittuoro-ethyl-vinyl ether), an inflammable fuorinated ether with somewhat different properties, described by Orth (4) and Gamza, et d. (5). PHARMACOLOGY Ravent6s (2) investigated the pharmacological actaons o]: Fluothane in-animals and reported that full surgical anaesthesia was achieved after using a 2-4 per cent concentration of Fluotaane in air or oxygen for two tc five minutes. Anaesthesia was maintained with a concentration of 3.,t-0.8 per cent in premedicated dogs, and 1-1.2 per c.ent in unpremedicated ones. On the basis of aFluothane@ was supphed by Ayerst,
H. H. MACAI:rrNEY, M.B., r'.~.c.~.(c),, AND if,. W. J.A-CKSONw TFIE PROBLEMS associated with anaesthesia in src. all arlimals often do not appear until extensive surgical procedures are carried 9ut aild mortality occurs. Even then the mortality is likely to be attributed to th ~ surgery rather than the anaesthetic, and the suitability .of the species of arimal lused for the experimenfs planned may be questioned. Modern anaesthetic :echniques and agents are sometimes dismissed because they may require the s ~rvic~s of an anaesthetist, of-teh not available in the experimental laboratory, and ~_oo oJdten techniques are applied blindly without regard to the possibility of spei~'ies aifference. Barbiturates are used as the sole anaesthetic agent because of thelease 9f ad~inist~ation, but such techniques would result in a high morbidity and mortality if they were applied in man.Surprisingly little appears in the literature ~vith ~egard to anaesthesia for experimental animals, and as a result unnecessal T mortality occurs as techniques are evolved by trial and error.Although this is not a critical study of anaes~etie agents, this paper describes the simple technique employed using triclalor6thyle~e as the agent in fairly standard, though often quite extensive, gastricIphyslological experiments with cats. It contrasts this technique with those used previously , which had a much higher mortality, probably resulting from the hypoven~ilation and cardiovascular depression which often occurred.In this series an anaesthetic death is considered during the operation (and was not associated w~th g which the animal failed to recover consciousness befor~ Cats were used exclusively, and were gen~rallly o agents, though a few were colony-bred. An attempt wa in quarantine, usually for two weeks, and dur.i~g thi temper and pneumonitis vaccines. The operations ca construction of gastric pouches and their modifiFatioI cedures, including transthoracic, vagotomy. Mgny more than once, some as many as four times. Becau diathermy a non-explosive technique was essential. chlorethylene (Trilene| halothane (Fluothane~), p and thiopentone (Pentothal| A small experience wit in-~luded.
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