Dexamethasone Combined with Morphine Does Not Decrease Postoperative Nausea and Vomiting in Patients Undergoing Thyroidectomy or Parathyroidectomy

Objective: A prospective, randomized, double-blind study was conducted to investigate the efficacy of dexamethasone in the prevention of postoperative nausea and vomiting (PONV) in patients who underwent thyroid or parathyroid surgery, when combined with morphine injection at the end of general anesthesia. Methods: One hundred and twenty-two patients between 14 and 79 years old were included in this study. Group Ⅰ(N=80) consisted of patients who received dexamethasone (10 mg) before induction, and Group Ⅱ (N=42) consisted of those who received placebo (normal saline, 10 ml) before induction. Thirty-nine patients in group Ⅰ were given morphine (5 mg) by the anesthetists, before the end of general anesthesia. At 4 hr and 24 hr after surgery, the sensation of nausea and the incidence of vomiting were assessed. Results: At 4 hr after surgery, the sensation of nausea and incidence of vomiting were significantly higher in Group Ⅱ than in Group Ⅰ without morphine injection (P=0.009 and P=0.010, respectively) and significantly higher in patients receiving morphine than in patients without morphine of Group Ⅰ (P=0.026 and P=0.008, respectively). Conclusions: Preinduction with dexamethasone (10 mg) infusion can decrease PONV at 4 hr after surgery if morphine is not used, but dexamethasone infusion in conjunction with morphine injection before the end of general anesthesia does not decrease PONV.