If you’ve ever needed a tooth out, or had surgery of any kind, chances are you’ll have experienced use of an inhalational anaesthetic. All of the compounds shown above can induce general anaesthesia, and a range have been utilised since the initial discovery of nitrous oxide in the mid-1800s. Often, intravenous drugs will be used for induction of anaesthesia, but inhalational agents may then be used to maintain this – this graphic looks at how the drugs in use for this purpose have varied over the years.