Purpose of review: Nitrous oxide is by far the oldest anaesthetic still in routine use and its continued use is often questioned. Nitrous oxide is toxic with prolonged exposure, can damage the environment, causes pressure effects through expansion of closed air-filled spaces and has long been suspected of being harmful following chronic exposure to trace concentrations. What could possibly justify the continuing use of nitrous oxide?
Recent findings: This review will attempt to demonstrate that the harmful effects of nitrous oxide are limited and not relevant to the majority of ambulatory patients. The environmental effects of nitrous oxide derived from anaesthetic use are negligible and there is no convincing evidence of harm to personnel.
Summary: Not only is nitrous oxide almost certainly less hazardous than is sometimes perceived, it has numerous benefits which are not easily replicated by possible alternatives. In particular, its use improves the quality and safety of induction and maintenance of anaesthesia and facilitates faster recovery with minimal adverse effects. All of these benefits are achieved while at the same time reducing overall costs. With few significant drawbacks and numerous advantages, there appears still to be a valuable place for nitrous oxide in modern ambulatory anaesthesia.