Optimal Dose of Intrathecal Morphine for Postoperative Analgesia After Cesarean Delivery

Prospective, randomized, double-blind, controlled trial, with a non-inferiority design. Patients will be randomly assigned to receive either intrathecal morphine 50 mcg, 150 mcg, or 250 mcg based on a pre-assigned randomization sequence. This medication will be administered as part of their spinal anesthesia for cesarean delivery. the patient, clinician who administers the spinal anesthesia, and investigator who follows the patient will all be blinded to the dose of medication.

All patients will receive standard of care for cesarean delivery and routine nursing care. This includes: preoperative intravenous catheter placement with preoperative IV fluid, standard American Society of Anesthesiologists monitoring, and neuraxial anesthesia placement (either spinal or combined spinal epidural) in sterile fashion. Each patient will receive standard cesarean induction dose of intrathecal medication consisting of 1.5ml of 0.75% hyperbaric bupivacaine, fentanyl 25 mcg. At end of surgery, all patients will receive standard dose of ketorolac 30 mg IV and acetaminophen 1 gm IV and continue with redosing every 6 and 8 hours (respectively) for 24 hours. On arrival to PACU, all patients will receive standard nursing care with standard monitoring of side effects. On discharge from PACU, patients will be transferred to postpartum floor and receive standard nursing care and monitoring.

Over the following 24 hours, the patient will receive all standard post-cesarean care. For treatment of breakthrough pain, medications will provided be per standard care: oxycodone 5-10 mg PO every four hours PRN for pain. If the patient is not comfortable after receiving oral oxycodone they will be assessed by an anesthesia provider for either regional nerve block or additional opioids, as a one-time dose or by patient controlled analgesia (PCA).

For treatment for side effects, medications will provided be per standard care: ondansetron 4mg IV as first-line for nausea/vomiting, promethazine 6.25 mg IV or Haloperidol 0.5-1mg IV for refractory nausea/vomiting. Naloxone 0.04 mg IV for refractory pruritus.