[Risk assessment, prophylaxis and treatment for postoperative nausea and vomiting]

The incidence of postoperative nausea and vomiting in the general population has been estimated to have remained constant at around 20% to 30% in recent years, but it can reach 80% in high-risk patients. A wide range of risk factors related to patient variables, anesthetic technique, or surgery have been described. However, risk can be classified by taking only 4 factors into consideration: female gender, nonsmoker, a history of motion sickness or postoperative vomiting, and use of opioids for postoperative analgesia. Antiemetic prophylaxis is not recommended for patients at low-risk (only 1 risk factor or none). Considering prophylaxis is recommended for patients at moderate risk (2 risk factors). For patients at high risk (3 or 4 risk factors), prophylaxis should be provided with 4 mg of intravenous ondansetron 30 minutes before ending surgery, 4 mg of intravenous dexamethasone at anesthetic induction, or both. Besides medical prophylaxis, strategies for lowering underlying risk are recommended: use regional anesthesia whenever possible, use total intravenous anesthesia with propofol if regional anesthesia is impossible, keep opioid and neostigmine use to a minimum, and try to maintain adequate hydration during surgery. Once preventive measures are taken, therapeutic options are limited and the management of postoperative nausea and vomiting, once established, is difficult.