Dexamethasone versus a combination of dexamethasone and ondansetron as prophylactic antiemetic in patients receiving intrathecal morphine for caesarean section.

BACKGROUND Intrathecal morphine for caesarean delivery provides excellent postoperative analgesia but it is commonly associated with nausea and vomiting. This prospective, randomized, double blind study was carried out to compare the effectiveness of a combination of dexamethasone and ondansetron with dexamethasone alone for prevention of postoperative nausea and vomiting (PONV) following intrathecal morphine injection for caesarean section. METHODS A total of 108 parturients aged 18-40 years for elective caesarean section were randomized into 2 groups (n=54) to receive either intravenous dexamethasone 8 mg (Group A) or a combination of intravenous dexamethasone 8 mg and ondansetron 4 mg (group B). The study drug for each group consisted of 0.5% hyperbaric bupivacaine and 0.2mg morphine. The primary outcome variables were postoperative nausea and vomiting (PONV) which were assessed for a period of 24 hours. The patient's vital signs were monitored and documented. RESULTS The incidence of nausea and vomiting was significantly reduced in patients who received a combination of dexamethasone and ondansetron compared with dexamethasone alone (9.3% Vs 37%, respectively, P = 0.003). CONCLUSION This study showed that a combination of dexamethasone and ondansetron administered prophylactically significantly reduced the incidence of PONV in pregnant women on intrathecal morphine for caesarean section.