The antiemetic effect of dexamethasone during continuous subcutaneous infusion of morphine for postoperative pain relief

Background: Dexamethasone is known to reduce the incidence of postoperative nausea and vomiting, associated with perioperative intrathecal, epidural, or intravenous morphine. However, the effect of dexamethasone on subcutaneous morphine is unclear. Therefore, we evaluated the antiemetic effect of intravenous dexamethasone during continuous subcutaneous infusion of morphine for post-operative pain relief. Methods: Twenty patients scheduled for spinal surgery under general anesthesia were enrolled in this randomized, double-blind, and placebo-controlled study. The dexamethasone group (n = 10) received dexamethasone 8 mg and the saline group (n = 10) received the same amount of saline before the induction of anesthesia. Anesthesia was maintained with propofol and fentanyl. Postoperative pain was treated with continuous subcutaneous morphine via a patient-controlled analgesia device. Postoperatively patients were assessed during 48 hours for nausea and vomiting. Results: Nausea or vomiting ascribable to the subcutaneous morphine developed in 40% of the patients in each group (P:NS). Conclusions: Our results suggest that the single dose of dexamethasone (8 mg) does not reduce postoperative nausea and vomiting associated with continuous subcutaneous infusion of morphine after spinal surgery.