The purpose of this study was to evaluate the effectiveness of additional ramosetron injection for controlling late postoperative nausea and vomiting (PONV) after breast surgery in high risk PONV patients. The investigators compared PONV amomng 3 groups- group C: no additional ramosteron, group B: two additional ramosteron doses at 12 hour interval, group M: two additional ramosetron doses mix to the intraveonus patient controlled analgesia.

The investigators included high risk patients of PONV with a score of 3 or more as measured by the Apfel's score and over 18 years old who receive breast surgery and intravenous patient controlled analgesia. All patients was received ramosetron 0.3 mg at the end of surgery. The patients were evaluated for number of PONV (nausea, vomiting, retching) at 1, 6, 24, and 48 hours postoperatively. Nausea was defined as an unpleasant feeling of vomiting. Retching was defined as an excessive contraction or a regular movement. of the respiratory muscles where no gastric contents were excreted, and vomiting was defined as the excretion of gastric contents. PONV were further detailed quantified using the RINVR score (Rhodes Index of Nausea, Vomiting, and Retching) which enabled the patients' objective and subjective symptoms to be evaluated as a simple and reliable methods.

Intravenous injection of ondansetron 4 mg was administered as a rescue antiemetic. The patients were evaluated 2 hours after ondansetron administration. If the symptom persisted, use of second rescue antiemetics dexamethasone 5 mg.

Inclusion Criteria:

• age over 18 years
• American Society of Anesthesiologists (ASA) physical status I or II
• requesting IV PCA (patient control of analgesia) for pain control
• the high-risk group of PONV with a score of 3 or more as measured by the Apfel's score.

Exclusion Criteria:

• emergency operation
• re-operation
• drug abuse, allergy
• major organ disease (gastrointestinal, cardiovascular, respiratory, cerebral, renal or hepatic disease)
• smoker
• pregnancy
• lactation
• previously use of antiemetics or systemic steroids within 48 before surgery