General anesthesia can be divided into intravenous anesthesia and inhalation anesthesia, which are often used in combination. Intravenous anesthesia is administered intravenously, while inhalation anesthesia is inhaled through the mouth or nose. The choice of general anesthesia is based on the condition, the length of operation time and the need of operation mode. As for the pain? Because your operation takes a long time, you need to do tracheal intubation, and then use drugs to maintain anesthesia to ensure your life safety. Before intubation, you should use drugs to let you sleep before operation, and there will be no pain.