Effects of nitrous oxide on intraoperative bowel distension

To evaluate evidence and present an objective view on the effect of nitrous oxide on bowel function.

We determined in a metaanalysis that the chance of having intraoperative bowel distension was increased about two fold in patients receiving nitrous oxide as the anaesthetic carrier gas compared with those receiving nitrogen or oxygen. In a separate logistic regression analysis, we found that the duration of nitrous oxide exposure was a key factor in explaining this difference, as well as the variability of previously published data. In contrast to bowel distension, surgical operating conditions were not hindered by the use of nitrous oxide; however, the number of patients analysed for operating conditions was much less than that for bowel distension data.

Nitrous oxide causes clinically and statistically recognizable bowel distension. This distension, however, does not always exacerbate the surgical conditions, nor does it appear to delay bowel movement or hospital discharge. Although no major problems were noted in bowel functions other than distension, we recommend avoiding nitrous oxide administration during prolonged bowel operations.