Fluothane: A Non-explosive Volatile Anaesthetic Agent

Abstract

"Fluothane" is a new volatile anaesthetic agent developed and manufactured by Imperial Chemical Industries (Raventos, 1956; Raventos and Suckling, 1956). It is the most promising member of a series of agents with non-flammable and non-explosive properties which are being investigated independently by the Medical Research Council. It is a clear, colourless, heavy liquid with a specific gravity of 1860 (cf. chloroform 1500), a boiling-point of 510 C., and a sweetish odour not unlike that of chloroform. Chemically, it is a halogenated ethane with the structural formula F BrFluothane has been administered as the sole or the principal anaesthetic agent to a number of volunteers and to 310 patients (varying in age from 7 months to 91 years) for a variety of surgical procedures (lasting from 3 to 150 minutes). There were no deaths under anaesthesia in the series, although many of the patients came to operation in a poor physical state. The pre-operative conditions included diabetes, obstructive jaundice, cardiac failure, thyrotoxicosis, and asthma, but none were affected adversely by the anaesthetic.One patient died during the post-operative period, but this was probably not attributable to the anaesthetic.An 84-year-old man received open drop fluothane for the amputation of a gangrenous toe. The administration was uneventful and lasted for 15 minutes. The patient recovered consciousness before leaving the operating theatre and was quite well for the next four days. He then became increasingly irrational, developed bronchopneumonia, and died on the seventh post-operative day.Tlhe object of this investigation was to confirm the promising results obtained in animal trials ; to ascertain in humans the effect of known concentrations of fluothane vapour; and to exploit the administration of the drug by simple methods. Methods of AdmuinistrationSince it was known that the administration of fluothanein conjunction with nitrous oxide and oxygen from a standard Boyle apparatus was being investigated elsewhere (Johnstone, 1956) Macintosh, 1956) modified and calibrated to deliver known concentrations of fluothane vapour in air. In this way it has been possible to observe the action of fluothane without the complication of other anaesthetic agents, and to obtain an im-*The trade name given by Imperial Chemical Industries to 2-bromo-2-chloro-1,1,1-trifluoro-ethane. The drug is not yet freely available. pression of the effec:s produced by known concentrations of the agent.Open Drop Induction.-Fluothane has been administered by the open drop method to 63 patients and to a further 29 after the preliminary injection of a " sleep " dose of thiopentone (rarely more than 0.2 g.).. In most instances, induction was smooth and pleasant, producing unconsciousness in about one minute. Swallowing during induction was not uncommon, but this did not interfere with the administration and was not followed by vomiting. Coughing was rare and was always relieved by raising the mask. Struggling and breath-holding were unusual. Surgical intervention cou...

"Fluothane": A Report to the Medical Research Council by the Committee on Non-Explosive Anaesthetic Agents

“…For this reason the blood-pressure level throughout these operations was unduly low. Further, as has been reported by Bryce-Smith and O'Brien (1956), pulmonary ventilation was depressed during fluothane anaesthesia, especially if the level was sufficient to allow intra-abdominal surgery. It was therefore considered necessary to assist or control the breathing in a large number of our cases.…”

“…The results of clinical trials with fluothane have been reported by Johnstone (1956) and by Bryce-Smith and O'Brien (1956). The Committee has carried out a trial with fluothane in 245 patients undergoing surgical operations in four teaching hospitals.…”

“…Recently " fluothane "t (halothane) has been prepared by Imperial Chemical Industries Ltd. (Pharmaceuticals Division), and reports on its properties and clinical use have been published (Ravent6s, 1956;Johnstone, 1956 ;Bryce-Smith and O'Brien, 1956). Chemically it is a derivative of ethane, in which three of the hydrogen atoms have been substituted by fluorine, a fourth has been substituted by bromine, and a fifth by chlorine.…”

Newer anesthetics end their uses

“…83 It is nonflammable and nonexplosive when the vapor is mixed with oxygen. 23 Halothane is metabolized by cleavage of the C-Cl bond and possibly of the C-Br bond by enzymes present in microsomes. The C-F bond is not easily broken and, hence, the major products of metabolism are chloride, bromide, and trifluoroacetic acid.…”

Observations on Various Actions of Fluothane

“…E. ECKENHOFF et al (1956)' with the following modifications: (1) A microcatheter technique was used to allow to-and-fro sampling of respired gases without interposing dead space;…”