Opioid-based patient controlled analgesia (PCA) provides adequate pain control following spinal surgeries at the expense of increased risk of postoperative nausea and vomiting (PONV). We evaluated the efficacy of dexamethasone added to ramosetron, which is a newly developed five-hydroxytryptamine receptor 3 antagonist with a higher receptor affinity and longer action duration compared to its congeners, on preventing PONV in highly susceptible patients receiving opioid-based IV PCA after spinal surgery.

One hundred nonsmoking female patients undergoing spinal surgery were randomly allocated to either a ramosetron group (group R) or a ramosetron plus dexamethasone group (group RD)., Normal saline (1 ml) or 5 mg of dexamethasone was injected before anesthetic induction, while at the end of the surgery, ramosetron (0.3 mg) was administered to all patients and fentanyl-based IV PCA was continued for 48 hrs. The incidence and severity of PONV, pain score and the amount of rescue antiemetics were assessed for 48 hours after surgery.

The number of patients with moderate to severe nausea (20 vs. 10, P = 0.029), and overall incidence of vomiting (13 vs. 5, P = 0.037) were significantly lower in the group RD than in the group R, respectively. Rescue antiemetic was used less in the RD group without significance.

Combination of ramosetron and dexamethasone significantly reduced the incidence of moderate to severe nausea and vomiting compared to ramosetron alone in highly susceptible patients receiving opioid-based IV PCA after surgery.