1, patients and doctors should have a comprehensive and in-depth preoperative conversation to understand the size and steps of the operation, the speed of pain recovery and possible effects; Possible risks; Doctors should know the patient's face, the motivation of the operation and whether the expectation of the operation is in line with reality.

2. Physical examination: exclude possible internal medical diseases such as heart, lung, liver and blood, previous surgical history, medication history and allergic history.

3. Stop drinking one week before the operation and stop using vasodilators such as aspirin and vitamin E..

4. Wash your hair once a day for 3 days before operation; Sleeping pills can be taken properly one night before operation, and sedatives and painkillers can be used as appropriate half an hour before operation; Decide whether fasting is necessary according to the anesthesia.