Toxicity of inhalation anaesthetic agents.

Although hundreds of compounds on the chemist's shelf are known to produce anaesthesia, relatively few are used clinically. The requirements for a clinically useful anaesthetic agent are necessarily stringent and include: a wide margin of safety, total reversibility of anaesthetic effect and an absence of long-term toxicity. In addition, a successful inhalation anaesthetic agent must combine the capacity for depression of the central nervous system with low levels of interference with respiration and the circulation. The central nervous system effects must be quickly reversible. The acute depressant effects produced by the inhalation anaesthetics contrast with the slower development of long-term toxicity involving organs such as the liver, the kidneys or the reproductive system. Although such long-term toxicity associated with anaesthetics has been recognized for many years, in the past it has been considered to occur infrequently, to be of little importance and of undetermined aetiology. More recent findings suggest that not only are these long-term effects serious, but they occur more frequently than was previously recognized. In addition the aetiological factors are now beginning to be understood.