While Patient-controlled analgesia (PCA) has the advantage of effectively reducing the degree of postoperative pain, it can also affect the patient's outcome by several adverse effects such as postoperative nausea and vomiting (PONV). Especially for high risk group of patients for PONV, the ideal regimen for sufficient analgesia with minimal adverse effect needs to be sought. Propacetamol is known for its effective, rapid analgesia, opioid-sparing effect, and is used widely for post operative pain management. This study aims to see the opioid-sparing effect and the degree of PONV when propacetamol is added to PCA for high risk PONV patients.

Inclusion Criteria:

1. Patients scheduled for either 1-2 level spine fusion or laminectomy
2. ASA (American Society of Anesthesiology) physical status 1 or 2
3. Non-smoking female patients, between the age 20 and 65

Exclusion Criteria:

1. Administration of any anti-emetic agents within 24 hours prior to surgery
2. Administration of any opioid agents within 7 days prior to surgery
3. Regular administration of any steroid agents
4. Drug or alcohol-abuser
5. Patients with bowel movement disorder, liver or renal impairment, insulin-dependent diabetes. Patients who are pregnant, illiterate, or foreign.
6. Patients administered to Intensive Care Unit after surgery