Yu fought at the Battle of Fancheng, this story of him performing surgery on Guan Yu has become a popular artistic theme. The historical document Sanguozhi recorded that there were actually a bone surgery performed on Guan Yu, and Guan Yu indeed showed no painful expression. Sanguozhi neither told the name of the surgeon nor the time of the operation, though. Hua Tuo is later summoned by Cao Cao to cure a chronic excruciating pain in his head, which turns out to be due to a brain tumour. Hua Tuo tells Cao Cao that in order to remove the tumor, it would be necessary to open up the brain by cutting open the head, getting the tumor out, and sewing it back, with Cao Cao completely anesthesized in the process. However, Cao Cao suspects that Hua Tuo is planning to murder him so he has Hua Tuo arrested and imprisoned. (Cao Cao's suspicions are in part due to a previous attempt by Ji Ping, an imperial physician, to force him to consume poisoned medicine.) In Romance of the Three Kingdoms, Hua Tuo passes his Qing Nang Shu to a prison guard so that his medical legacy will live on. He dies in prison later. The prison guard's wife burnt the book for fear of being implicated, but the guard manages to salvage some pages, which are about how to emasculate hen and ducks; the other pages are lost forever. Mafeisan Hua Tuo's innovative anaesthetic mafeisan (literally "cannabis boiling powder", considered to be the first anesthetic in the world), which was supposedly used on Hua Tuo's patients during surgery, is a long-standing mystery. The Records of the Three Kingdoms and the Book of the Later Han both credit him as creating this anesthetic during the Eastern Han Dynasty. However, no written record or ingredients of the original have been found, although estimations have been made by Chinese medical practitioners in later periods of time. There is controversy over the historical existence of mafeisan in Chinese literature. The name mafeisan combines ma (; "cannabis; hemp; numbed"), fei (; "boiling; bubbling") and san (; "break up; scatter; medicine in powder form"). Ma can mean "cannabis; hemp" and "numbed; tingling" (e.g. mazui "anesthetic; narcotic"), which is semantically "derived from the properties of the fruits and leaves, which were used as infusions for medicinal purposes". Modern Standard Chinese mafei is reconstructed as Old Chinese *mrâipəts,