Clinical Question

Which patients are likely to experience postoperative nausea and vomiting?

Evidence Summary

Postoperative nausea and vomiting are uncomfortable for patients, can prolong hospitalization, and can lead to more serious complications, including aspiration pneumonia. Accurately predicting which patients are at risk of postoperative nausea and vomiting can help physicians decide when to recommend prophylactic antiemetics. A study comparing different prophylactic strategies concluded that dexamethasone with or without ondansetron (Zofran), ideally administered intraoperatively, should be used as initial agents.¹

A review found three predictive scores for postoperative nausea and vomiting and attempted to validate them in 1,444 patients.² Another review identified three additional predictive scores and attempted to validate all six scores in 1,566 patients.³ Participants in both validation studies were undergoing general anesthesia without prophylactic antiemetics. A subsequent study used a neural network (i.e., artificial intelligence software) to predict postoperative nausea and vomiting; however, this is not practical for physicians without specialized software.⁴

The scores vary considerably in complexity. Some are multivariate equations that are not practical for bedside use without a calculator; however, simpler scores consisting of four or five items have been shown to be as accurate or nearly as accurate as more complex equations.^2–6

The Apfel score (Table 1⁵) includes four variables and assigns one point for each. The score was prospectively validated in 520 patients from a different hospital than that used in the original study and was found to have good predictive accuracy.^3,5 The Koivuranta score (Table 2⁶) includes five variables and assigns one point for each. The score was also shown to validate well in several studies.^2,3,6 Both scores performed similarly in the validation studies. Another study found that both scores performed well in a prospective comparison in 1,388 Dutch inpatients.⁷

Applying the Evidence

A 54-year-old female nonsmoker is about to undergo a laparoscopic cholecystectomy. The surgeon estimates that the procedure will take 90 minutes, and predicts that she will require postoperative opioids for pain relief. The patient has no history of postoperative nausea and vomiting because she has never been under general anesthesia, but she is somewhat susceptible to motion sickness. What is the patient's risk of postoperative nausea and vomiting?

Answer: Using the Apfel score (Table 1⁵), the patient receives four out of four possible points. Using the Koivuranta score (Table 2⁶), she receives four out of five possible points. You refer to a recent study that recommends 4 mg of dexamethasone and 4 mg of ondansetron for prevention of postoperative nausea and vomiting, and recommend that she receive these antiemetics intraoperatively.¹