The incidence of postoperative nausea and vomiting (PONV) after thyroidectomy have been shown to be relatively high compared other surgeries, with a reported incidence 65-75 %. PONV may increase patient discomfort, delay patient discharge, and increase the cost of patient care, the risk of postoperative bleeding which may potentially cause airway obstruction.

It is reported that the maintenance of anesthesia with propofol-remifentanil or sevoflurane-propofol-remifentanil decreased the incidence of PONV compared sevoflurane alone, but failed to demonstrate the decreased incidence of PONV in 6-24 hr postoperative period in patients undergoing thyroidectomy. Administration of Palonosetron, newly developed 5-HT3 antagonists with long half life (48 hrs) may decrease the incidence of PONV particularly during this period.

The purpose of this study was to evaluate and compare the incidence of PONV after thyroidectomy with three different anesthetic methods, sevoflurane or sevoflurane-propofol-remifentanil or sevoflurane-propofol-remifentanil-palonosetron in woman patients.

Inclusion Criteria:

• patients undergoing thyroidectomy euthyroid status American Society of Anesthesiology Physical status 1,2

Exclusion Criteria:

• Ideal body weight >130% gastrointestinal disease prior administration of anti-emetics (24hr)