Comparing Ondansetron with Ondansetron-Dexamethasone Combination on Postoperative Nausea and Vomiting after Elective Abdominal Surgeries: A Randomized Double Blinded Clinical Trial

Background: Postoperative nausea and vomiting (PONV) is an unpleasant and distressing complication after abdominal surgeries. We conducted a study to compare the efficacy of Ondansetron-Dexamethasone combination with ondansetron alone on PONV after abdominal surgeries under general anesthesia. Methods: Two hundred patients undergoing elective abdominal surgeries under general anesthesia were allocated into two equal groups and anesthetised with the same technique. In one group combination of 8mg dexamethasone (2ml) and 4mg ondansetron (2ml) and in the other group ondansetron plus normal saline with the same volume was injected ten minutes before induction of anesthesia. PONV at recovery and during the first 24 hours after surgery were compared between the study groups. Results: Twenty-two patients in ondansetron group and nine patients in ondansetron plus dexamethasone group had PONV respectively at first hour in recovery room (P=0.01). Eight patients in ondansetron group and no patient in ondansetron plus dexamethasone group had PONV at first 24 hours after surgery in the ward (P=0.007). In ondansetron group 21 patients and in combination group 7 patients needed intravenous metoclopramide as rescue medication for treatment of PONV in recovery (P=0.02). Two patients in ondansetron group needed intravenous rescue medication for treatment of PONV in the ward (P=0.01). Conclusion: Dexamethasone plus ondansetron was more effective than ondansetron alone in preventing postoperative nausea and vomiting in patients undergoing elective abdominal surgeries.