Bupivacaine

The intrathecal intervention consists of 3 mg bupivacaine plus 0.25 mg morphine diluted with cerebrospinal fluid to a total volume of 3 mL and injected over 15 seconds. Bupivacaine spinal anaesthesia typically lasts no more than 150 minutes, so sensory or motor dysfunction persisting beyond 3 hours after surgery is classified as an adverse effect. Bupivacaine may alter intraoperative analgesic requirements, creating a potential blinding weakness for the general anaesthesia provider. Bupivacaine is combined with intrathecal morphine specifically to address the perioperative acute pain gap created by morphine's delayed peak effect.