Toxin removal, regulation of acid-base balance and metabolic disorders. The role of blood purification mainly includes: 1, replacing part of the kidney function, with the role of removing water, expelling toxins, regulating acid-base balance and metabolic disorders; 2, for patients with acute poisoning, drug poisoning and toxic poisoning for first aid, the hemoperfusion plus hemodialysis method is generally used; 3, for patients with renal failure, whose kidney failure or high edema occurs, the dialysis method is used, which can reduce heart failure patients’ cardiac load, as well as alleviate the symptoms of their high edema.