The Comparison of Efficacy between Intrathecal Morphine Combined with Either Intravenous Selective COX-II Inhibitor or Acetaminophen and Intrathecal Morphine Alone for Analgesia after Cesarean Section: A Double-Blinded Randomized Controlled Trial

Background: Spinal anesthesia is a popular anesthetic of choice for cesarean section but inadequate analgesia may result in delayed ambulation and healing after surgery. Multimodal analgesia is currently applied to decrease the adverse effect of each medication, enhance analgesic efficacy and promote Enhanced Recovery After Surgery (ERAS). Non-steroidal anti-inflammatory drugs (NSAIDs) and acetaminophen are recommended for enhanced recovery after cesarean section (ERAC). Objective: To compare the analgesic efficacy of a combination of acetaminophen or selective COX-II inhibitors with intrathecal morphine and intrathecal morphine alone after cesarean section. Materials and Methods: Eighty-eight parturients undergoing cesarean section were divided into three groups. Acetaminophen group: intrathecal morphine 0.1 mg and intravenous acetaminophen 1 gram every 6 hours. Parecoxib group: intrathecal morphine 0.1 mg and intravenous parecoxib every 12 hours. Control group: intrathecal morphine 0.2 mg only. The primary outcome was total morphine consumption in the first 24 hours postoperatively. The secondary outcomes were pain intensity, vomiting episodes, and time to first dose of opioid. Results: The parecoxib group showed total morphine reduction in the first 24 hours of 10.655 mg (95% CI –15.04 to –6.27, p<0.001) compared with the control group. The pain intensity at rest and movement decreased in the parecoxib group compared to the control group at 4, 8, and 12 hours postoperatively (at rest: p=0.020, 0.001, and 0.002, at movement: p=0.002, 0.002, and 0.002). The acetaminophen group showed reduction of the pain intensity at 4 hours postoperative compared with the control group (p=0.011). Vomiting episodes and total ondansetron consumption were lower in the parecoxib group and the acetaminophen group. The parecoxib group also showed prolonged time to first dose of opioid usage. Conclusion: Parecoxib decreased total opioid consumption, decreased postoperative vomiting episodes and increased time for first dose opioid requirement. Acetaminophen also reduced the pain intensity and vomiting at 4 hours postoperative. The alternative and multimodal concepts in intraoperative and postoperative pain medications are the easiest ERAC components to improve outcome for the anesthesiologist. Keywords: Acetaminophen; Cesarean section; COX-II inhibitor; Intrathecal morphine