To examine whether surgical infiltration of the rectus abdominus muscle with Levobupivacaine (Rectus Sheath Block) prior to wound closure improves post-operative patient satisfaction, post-operative pain scores and reduces patient controlled analgesia (PCA) morphine consumption following open gastric bypass for the treatment of morbid obesity via an upper abdominal midline incision. Our Primary endpoint will be post-operative morphine PCAS use.