Comparison of 0.1 and 0.05mg Intrathecal Morphine When Administered With a Multimodal Pain Regimen for Post-cesarean Analgesia

The purpose of this study is to determine the ideal dose of spinal morphine for use in Cesarean section. Spinal anesthesia (single injection in the lower back to numb patients from the waist down) is commonly used in Cesarean section to provide numbness and pain relief during the surgery, and adding morphine to the spinal anesthetic provides long lasting pain relief for up to 24 hours after surgery. The ideal dose of spinal morphine, when given with other types of pain medications such as nonsteroidal anti-inflammatories and acetaminophen, has not been determined. In addition, spinal morphine can have side effects such as nausea and itching, so using a lower dose of morphine may decrease these side effects while providing the same amount of postoperative pain relief. Study participants will be divided into two groups. Group 1 will receive the standard dose of spinal morphine (0.1mg) while Group 2 will receive a lower dose of spinal morphine (0.05mg). Both groups will receive the standard dose of spinal bupivacaine (numbing medication) and spinal fentanyl (short acting pain medication). The additional pain medications (IV Toradol and oral acetaminophen) will be given to both groups after surgery. Pain control and morphine side effects will be compared between the two groups in order to determine the best dose of spinal morphine for cesarean section.