Effect of Intravenous Dexamethasone on Postoperative Nausea-Vomiting (PONV) after Intrathecal Morphine during Caesarean Section

Background: Post-operative pain relief after Caesarean section is important; it improves mobility and reduces the risk of thromboembolic complications. Neuraxial opioids are effective in postoperative pain relief but untoward effects like postoperative nausea and vomiting (PONV) prevent their regular use. Recent studies have shown that IV Dexamethasone reduces the incidence of PONV associated with intrathecal opioids when used for post Caesarean analgesia. We evaluated the efficacy of 8mg IV dexamethasone in reducing PONV in mothers receiving intrathecal morphine for post Caesarean analgesia. Methods: Hundred mothers scheduled for LSCS under spinal anaesthesia were randomly assigned to receive either 2ml saline (Group A, n=50) or 8mg IV dexamethasone (Group B, n=50) in this prospective double-blinded study. All mothers received a standard spinal anaesthetic with 2.5 ml 0.5% heavy bupivacaine and 0.2 mg intrathecal morphine for post Caesarean analgesia. APGAR scores of the babies were noted at 1min and 5min. All the mothers were assessed postoperatively for nausea/vomiting, pain, pruritus and urinary retention in the post anaesthesia care unit (time 0 hours) and at 1, 2, 3, 4, 8, 12, 16, 20 and 24 hours. 4mg IV ondansetron was given to patients who complained of nausea or vomiting and 75mg IM diclofenac was given to any mother who complained of pain postoperatively Results: The incidence of nausea and vomiting scores were found to be lower in the study group when compared to the control group with 27 out of 50 subjects requiring antiemetic in the control group while only 15 out of 50 subjects requiring antiemetic in the study group (P=0.015). Time to request to first analgesic dose was 15 hours in the study group when compared to 13 hours in the control group (P=0.024). However, no difference in APGAR scores, pruritus and urinary retention was noted in both the groups (P > 0.005). Conclusion: Dexamethasone reduces the incidence of postoperative nausea and vomiting associated with intrathecal morphine. Additionally, it can prolong the duration of analgesia postoperatively.