Role of Prophylactic Antiemetics in Women Receiving Intrathecal Morphine and Lipophilic Opioids Added to Bupivacaine for Cesarean Section

Overview

Because the majority of Caesarean deliveries are performed under neuraxial anaesthesia, Intrathecal morphine has become the gold standard for post-Caesarean delivery analgesia. However, postoperative nausea and vomiting (PONV) is the common side-effect of intrathecal morphine, affecting up to 60-80% of women without prophylaxis. PONV reduces maternal satisfaction and delays discharge from hospital, so it is important to prevent PONV in contemporary obstetric anaesthesia, particularly in the context of Enhanced Recovery After Surgery (ERAS) after Caesarean delivery. According to the meta-analysis by Lizhong Wang et al., combined 5-HT3 antagonists plus dexamethasone are more effective than mono-therapy in preventing PONV associated with intrathecal morphine after Caesarean delivery. But, the role of prophylactic antiemetics in women receiving intrathecal morphine and lipophilic opioids is still unclear. As antiemetics were shown to be less effective in women receiving intrathecal morphine than in those receiving epidural morphine, Lizhong Wang et al., performed a further subgroup analysis based on whether intrathecal morphine was combined with lipophilic opioids or not. Surprisingly, the results in women who received intrathecal morphine alone were similar to those in the primary analyses; however, in those who received intrathecal morphine and lipophilic opioids, there were no statistical differences in almost all comparisons. This raises the question of whether the combination of intrathecal lipophilic opioids contributed to the reduced efficacy of antiemetics in women receiving intrathecal morphine The objective of the current study is to examine the effect of prophylactic use of combined 5-HT3 antagonists plus dexamethasone to decrease the incidence of postoperative nausea and vomiting in parturients undergoing CS under spinal anaesthesia who receive intrathecal morphine alone or combined with lipophilic opioids.

Because the majority of Caesarean deliveries are performed under neuraxial anaesthesia, Intrathecal morphine has become the gold standard for post-Caesarean delivery analgesia. However, postoperative nausea and vomiting (PONV) is the common side-effect of intrathecal morphine, affecting up to 60-80% of women without prophylaxis. PONV reduces maternal satisfaction and delays discharge from hospital, so it is important to prevent PONV in contemporary obstetric anaesthesia, particularly in the context of Enhanced Recovery After Surgery (ERAS) after Caesarean delivery. According to the meta-analysis by Lizhong Wang et al., combined 5-HT3 antagonists plus dexamethasone are more effective than mono-therapy in preventing PONV associated with intrathecal morphine after Caesarean delivery. But, the role of prophylactic antiemetics in women receiving intrathecal morphine and lipophilic opioids is still unclear. As antiemetics were shown to be less effective in women receiving intrathecal morphine than in those receiving epidural morphine, Lizhong Wang et al., performed a further subgroup analysis based on whether intrathecal morphine was combined with lipophilic opioids or not. Surprisingly, the results in women who received intrathecal morphine alone were similar to those in the primary analyses; however, in those who received intrathecal morphine and lipophilic opioids, there were no statistical differences in almost all comparisons. This raises the question of whether the combination of intrathecal lipophilic opioids contributed to the reduced efficacy of antiemetics in women receiving intrathecal morphine