There are several proposed mechanisms by which nitrous oxide may cause post-operative nausea and vomiting (PONV). Some of these mechanisms include bowel distention and decreased gastrointestinal function, changes in middle ear pressure, and increase in sympathetic nervous system stimulation, and activation of opioid receptors in the brain. Bowel distention may contribute to nausea and vomiting in two ways. Nitrous oxide is known to diffuse into body cavities and this increase in bowel volume may cause …showed first 75 words of 274 total…

…showed last 75 words of 274 total…atmospheric pressure (Perreault). The administration of nitrous oxide can also cause an increase in the sympathetic nervous system stimulation leading to the release of catecholamines. This release of catecholamines is correlated with an increase in PONV (Muir, Eger, Gillman, Murakawa). Finally, since nitrous oxide is known to provide analgesia (Eger) it is also proposed that it may act as an opioid receptor agonist and produce nausea and vomiting in the same way that morphine does.