Nitrous oxide in 2010: who will have the last laugh? (Part 1)

Nitrous oxide (N2O) has been a part of anaesthetic practice for over 150 years. During this time, its reputation has seesawed. Today, anaesthetic opinion seems to have swung away from its use. To ascertain whether this is based on sound scientiŠ c principles, or can be ascribed to a shift in “medical fashion”, a Pubmed search for all articles containing the terms “nitrous oxide” and “anaesthesia” was conducted for the period 2004 to 2009. Relevant articles were selected and supplemented with appropriate articles from their references. This three-part series thus reviews the current knowledge of nitrous oxide. In this, the first article of the series, the history and basic science are reviewed. The focus is on the latest knowledge regarding mechanisms of action and possible pathophysiological mechanisms, and the clinical relevance thereof. New considerations regarding preoperative assessment and premedication are also presented. The remainder of the series will deal with the clinical controversies surrounding nitrous oxide, analyse claimed risks and benefits, and discuss its role in 2010.