What are the primary risk factors for postoperative nausea and vomiting (PONV) identified in the chapter?

The primary risk factors for postoperative nausea and vomiting (PONV) include being under 50 years old, female gender, a history of motion sickness or PONV, being a nonsmoker, the use of volatile anesthetics, nitrous oxide, high doses of opioids, surgery lasting more than one hour, and undergoing laparoscopic surgery.