According to the grading scheme of the World Health Organization, pain can be divided into 5 grades, which are 0-4: Grade 0 is no pain; Grade 1 is mild pain, which is manifested as vague pain and intermittent pain, and this pain is generally tolerable and can be treated without medication; Grade 2 is moderate pain, which is mostly manifested as persistent dull pain, and the pain is relatively obvious, which will affect normal rest and requires consideration of oral Grade 3 pain is severe pain, which is characterized by persistent colic, and must be controlled by pain medication; Grade 4 pain is persistent severe pain, which is so intense that it affects the patient’s blood pressure, heart rate and other vital signs.