Blood exchange generally refers to plasma replacement, for example, when autoimmune diseases occur, producing various autoantibodies that are harmful to the body, or various kinds of poisoning, blood exchange can be used to replace excessive toxins or autoantibodies in the blood out of the body, so as to achieve the purpose of relieving symptoms and treating the disease. Indications for blood exchange include autoimmune diseases such as acute neonatal hemolytic disease and autoimmune hemolytic anemia, in which a large number of antibodies against red blood cells are produced in the blood, resulting in a series of symptoms due to lysis and destruction of red blood cells. Blood exchange therapy can be used to replace excess harmful antibodies in the blood to reduce the destruction of red blood cells and achieve the purpose of treating the disease. Various toxic diseases, such as Valium poisoning, acute alcohol poisoning, acute organophosphorus pesticide poisoning, poisonous mushroom poisoning, etc., can be treated by replacing the toxins in the blood through blood exchange therapy and feeding fresh blood into the patient.