How will you treat postoperative nausea and vomiting (PONV)?

How will you treat postoperative nausea and vomiting (PONV)?

PONV continues to be a problem. In ambulatory anes-thesia, where early discharge is an important issue, PONV can be a limiting factor in home readiness.

The first step in dealing with PONV is the identification of the high-risk patient. This particular patient is in the high-risk category because of gender (female), use of intra-operative opioids, and type of surgery. Other risk factors for PONV include being a non-smoker, history of PONV/ motion sickness, use of volatile anesthetics, use of nitrous oxide, duration of surgery, and type of surgery (laparoscopy, ear-nose-throat, neurosurgery, breast, strabismus, laparo-tomy, and plastic surgery). Once the high-risk patient is identified, strategies to decrease the risk, such as use of regional anesthesia when appropriate, use of propofol for induction and maintenance of anesthesia, intraoperative supplemental oxygen, avoidance of volatile anesthetics and nitrous oxide, no to minimal use of opioids, and hydration should be employed.

Since the cause of PONV is considered to be multifacto-rial in nature, treatment and/or prophylaxis should be sim-ilarly directed. There are several drugs currently being used for PONV prophylaxis in adults. These include serotonin receptor antagonists, dexamethasone, and metoclopramide. Older anti-emetics such as promethazine, haloperidol, and perchlorperazine may be used as well. Combination therapy with drugs from different classes has been shown to be superior to treatment with a single drug. The serotonin receptor antagonists (5-HT₃), ondansetron, dolasetron, granisetron, and tropisetron, are most effective when given at the end of surgery. According to Gan et al. (2003) there is no difference amongst the various serotonin (5-HT₃) recep-tor antagonists in their efficacy and safety profiles.

Dexamethasone (2.5–5 mg intravenously) has also been shown to be effective as prophylactic treatment for PONV and is most effective when given before induction.

Low doses (0.625 mg) of droperidol are also effective as prophylactic therapy when given at the end of surgery. It is of note that the US Food and Drug Administration (FDA) issued a “black box” warning that droperidol may cause death or life-threatening events associated with QT prolongation and torsades de pointes. This warning is based on 10 reported cases. Gan et al. state that had it not been for the FDA warn-ing, droperidol would have been their panel’s first choice for PONV prophylaxis.

Treatment of patients with PONV in whom prophylaxis has failed includes the administration of small doses of sero-tonin receptor antagonists (ondansetron 1 mg, dolasetron 12.5 mg, granisetron 0.1 mg, or tropisetron 0.5 mg). In general, the rescue drug should be selected from a different class than was used for prophylaxis.