Change time: 1. 7 days after surgery to remove the stitches 2. 10-15 days after surgery to remove the iodoform gauze filled in the surgical cavity. Zhang Yuli, Department of Otolaryngology, Affiliated Hospital of Chengde Medical College 3. There is a trauma in the mastoid cavity after radical mastoid treatment, and it is necessary to wait for the epithelialization of the trauma before the ear is dry, which means it takes about 2-3 months! The procedure of medication change: 1. remove the gauze from the mastoid cavity 2. clean the cavity twice with 3% hydrogen peroxide, wipe it dry, and spray chlorine powder on the surface of the cavity 3. refill the cavity with clean gauze (infiltrated with neocortisone or oxyfloxacin ear drops) 4. change the gauze every 2-3 days for the first 2-3 weeks after removing the gauze, and then decide the frequency of medication change according to the amount of exudation 5. clean the cavity scab once every 3-6 months 2. avoid air travel or strenuous activities for 3 months. 3. do not expose the ear and incision to water to prevent infection. 4. prevent upper respiratory tract infection (cold). 5. do not blow nose forcefully. 6. use medication as prescribed by the doctor and review regularly. 7. do not fly for 3 months.