We evaluated the timing effect of a 10-mg IV administration of dexamethasone on its efficacy as a prophylactic antiemetic on postoperative nausea and vomiting (PONV). One hundred twenty women (n = 40 in each of three groups) undergoing abdominal total hysterectomy under general anesthesia were enrolled in this randomized, double-blinded, placebo-controlled study. Group 1 received dexamethasone before the induction of anesthesia, Group 2 received dexamethasone at the end of anesthesia, and Group 3 received placebo (saline). The incidence of PONV was evaluated. During the postoperative period of 0-2 h, patients in Group 1 reported a less frequent incidence of PONV (15%) than those in Groups 2 and 3 (45% and 53%, respectively). Patients in Group 1 also requested less rescue antiemetic (8%) than those in Groups 2 and 3 (30% and 35%, respectively). During the postoperative period of 2-24 h, patients in both Groups 1 and 2 reported less frequent incidences of PONV (25% and 28%) and requested fewer rescue antiemetics (13% and 15%) than those in Group 3 (55% and 38%, respectively). In conclusion, the prophylactic IV administration of dexamethasone immediately before the induction, rather than at the end of anesthesia, was more effective in preventing PONV.
Implications: We evaluated the effect of timing of dexamethasone administration on its efficacy as a prophylactic antiemetic on postoperative nausea and vomiting. We found that dexamethasone, when given immediately before the induction of anesthesia, was more effective than when given at the end of anesthesia.