Effect of Combination Dexmedetomidine Added to Fentanyl-based Intravenous Patient-controlled Analgesia on Nausea Vomiting in Highly Susceptible Patients Undergoing Lumbar Spinal Surgery: Prospective Double Blinded Randomized Controlled Trial

The aim of this study is to test the hypothesis that addition of dexmedetomidine to fentanyl-based intravenous patient controlled analgesia (PCA) reduces requirement of fentanyl bolus and consequent postoperative nausea and vomiting in high-risk patients undergoing lumbar spine surgery.

Inclusion Criteria:

1. female, non-smoking patient who are 20-65 of age scheduled for elective lumbar spine surgery

Exclusion Criteria:

1. Bradycardia on EKG (45bpm)
2. Atrioventricular conduction disorder
3. Uncontrolled hypertension
4. angina history
5. obesity (BMI ≥ 30 kg/m2)
6. Preoperative administration of opioid
7. Preoperative administration of antiemetics
8. Gastrointestinal disorder history
9. Hepatic or renal disease
10. Pregnant 11. Foreigner