Biomaterial Database

Removal of halogenated anaesthetics from a closed circle system with a charcoal filter. 1989

V Højkjaer Larsen, and I Severinsen, and J Waaben

Department of Anaesthetics, Svendborg Hospital, Denmark.

Halogenated anaesthetics may be removed from a closed circle system by means of a charcoal filter. With this technique dispersion to the atmosphere and a possibly destructive effect of the halogenated volatiles on the protective layer of ozone is avoided. Removal of halothane or isoflurane with a charcoal filter was studied in a closed circle system connected to an artificial lung. The concentration of anaesthetic (Ct) was recorded in relation to time by an anaesthetic gas monitor interposed between the system and the lung at ventilations of 3, 5, 7 or 9 l/min (v). Based on theoretical considerations, it was expected that Ct = Co.exp (-v/V.t), (V: volume of the system). Analysis of regression demonstrated that the results fitted well to an exponential decrease (R2 greater than 0.94) and the downslope increased with increasing rate of ventilation. However, the slopes deviated significantly from the theoretically predicted slopes, possibly because of adsorption to hoses and bags and unequal distribution of the volatiles in the system. Halothane was eliminated more slowly than isoflurane. This study demonstrates that halogenated volatiles are eliminated in an exponential way following charcoal filtration and the rate depends on the ventilation and type of volatile.

UI	MeSH Term	Description	Entries
D007530	Isoflurane	A stable, non-explosive inhalation anesthetic, relatively free from significant side effects.
D008961	Models, Structural	A representation, generally small in scale, to show the structure, construction, or appearance of something. (From Random House Unabridged Dictionary, 2d ed)	Model, Structural,Structural Model,Structural Models
D002606	Charcoal	An amorphous form of carbon prepared from the incomplete combustion of animal or vegetable matter, e.g., wood. The activated form of charcoal is used in the treatment of poisoning. (Grant & Hackh's Chemical Dictionary, 5th ed)	Activated Charcoal,Actidose,Actidose-Aqua,Adsorba,Carbomix,Charbon,CharcoAid,CharcoCaps,Charcodote,Formocarbine,Insta-Char,Kohle-Compretten,Kohle-Hevert,Kohle-Pulvis,Kohle-Tabletten Boxo-Pharm,Liqui-Char,Norit,Ultracarbon,Charcoal, Activated
D004781	Environmental Exposure	The exposure to potentially harmful chemical, physical, or biological agents in the environment or to environmental factors that may include ionizing radiation, pathogenic organisms, or toxic chemicals.	Exposure, Environmental,Environmental Exposures,Exposures, Environmental
D005374	Filtration	A process of separating particulate matter from a fluid, such as air or a liquid, by passing the fluid carrier through a medium that will not pass the particulates. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Filtrations
D006221	Halothane	A nonflammable, halogenated, hydrocarbon anesthetic that provides relatively rapid induction with little or no excitement. Analgesia may not be adequate. NITROUS OXIDE is often given concomitantly. Because halothane may not produce sufficient muscle relaxation, supplemental neuromuscular blocking agents may be required. (From AMA Drug Evaluations Annual, 1994, p178)	1,1,1-Trifluoro-2-Chloro-2-Bromoethane,Fluothane,Ftorotan,Narcotan
D000764	Anesthesia, Closed-Circuit	Inhalation anesthesia where the gases exhaled by the patient are rebreathed as some carbon dioxide is simultaneously removed and anesthetic gas and oxygen are added so that no anesthetic escapes into the room. Closed-circuit anesthesia is used especially with explosive anesthetics to prevent fires where electrical sparking from instruments is possible.	Anesthesia, Rebreathing,Closed-Circuit Anesthesia,Anesthesia, Closed Circuit,Anesthesias, Closed-Circuit,Anesthesias, Rebreathing,Closed Circuit Anesthesia,Closed-Circuit Anesthesias,Rebreathing Anesthesia,Rebreathing Anesthesias
D000769	Anesthesia, Inhalation	Anesthesia caused by the breathing of anesthetic gases or vapors or by insufflating anesthetic gases or vapors into the respiratory tract.	Insufflation Anesthesia,Anesthesia, Insufflation,Inhalation Anesthesia