FORMATION OF CARBON-MONOXIDE IN ABSORBENTS

German and British health authorities have issued warnings drawing attention to American publications reporting unexpectedly high concentrations of carboxyhaemoglobin as high as 30% and more in patients undergoing inhalation anaesthesia. American and our own studies indicate that these accidental carbon monoxide intoxications stem from a chemical reaction of the inhalation anaesthetic agents with carbon dioxide absorbants leading to the production of carbon monoxide. Such reaction occurs, in decreasing order of magnitude, for desflurane, enflurane and isoflurane, brit is only slight in the case of halothane and sevoflurane. The highest concentrations of carbon monoxide resulted when the inhalation agent reacted with absolutely dry absorbent When the latter was even only partially moist CO production decreased dramatically; absorbents with normal water content do not react with the anaesthetic agents to produce CO. Although there have been no reports of clinically relevant CO intoxication to date, care should nevertheless be taken to ensure adequate moistening of the absorbent and to avoid any measures likely to lend to its drying out.