During first aid, if the patient’s organism is injured, it is usually necessary to fix the limb. Because the injury can bring pain, bleeding or even aggravate the injury, it is necessary to fix it for the following purposes: 1. Avoid aggravation of the injury: when the patient has a fracture, if the limb is not fixed, the patient will feel severe pain, fixing the limb can relieve the patient’s pain and avoid the fracture end from further damaging the surrounding tissues and large blood vessels, thus aggravating the condition; if the patient’s injury location is the spine, including the cervical spine, it is especially necessary to Fixation, if not fixed, may lead to paralysis of the patient. 2. Pain relief and hemostasis: patients with fractures of the extremities, if not fixed, patients usually experience painful symptoms, which may even lead to further injury and bleeding aggravation.