This area is on the floor of the fourth ventricle and is effectively outside of the blood-brain barrier, which makes it incredibly sensitive to toxin and pharmacological stimulation.
A 2008 study compared 121 Japanese patients who experienced PONV after being given the general anesthetic propofol to 790 people who were free of postoperative nausea after receiving it.
Patient factors that confer increased risk for PONV include female gender, obesity, age less than 16 years, past history of motion sickness or chemotherapy-induced nausea, high levels of preoperative anxiety, and patients with history of PONV.
[1] Other approaches to reduce PONV include decision on the types of anaesthetic used during surgery and intravenous (IV) dextrose solutions.
[citation needed] Fasting guidelines often restrict the intake of any oral fluid 2-6 hours preoperatively, but in a large retrospective analysis in Torbay Hospital, unrestricted clear oral fluids until transfer to theatre could significantly reduce the incidence of postoperative nausea and vomiting without an increased risk in the adverse outcomes for which such conservative guidance exists.
[6] In conjunction with antiemetic medications, at least one study has found that application to the pericardium meridian 6 acupressure point produced a positive effect in relieving PONV.
[10] Vomiting has been associated with major complications, such as pulmonary aspiration of gastric content, and might endanger surgical outcomes after certain procedures, for example after maxillofacial surgery with wired jaws.
Nausea and vomiting can delay discharge, and about 1% of patients scheduled for day surgery require unanticipated overnight admission because of uncontrolled PONV.