Hemodialysis is a common alternative treatment in modern medicine, and there are mainly the following types: hemodialysis, hemofiltration, continuous arteriovenous hemofiltration, hemoperfusion, immunoadsorption, plasma exchange, and peritoneal dialysis. Hemodialysis is the introduction of blood into the dialyzer, using the difference in solute concentration between the two sides of the semi-permeable membrane, through osmosis, diffusion and ultrafiltration, to achieve the purpose of removing metabolites and toxic substances, and correcting the disorder of water and electrolyte balance. Indications: 1. acute renal failure; 2. chronic renal failure; 3. acute poisoning. There is no absolute contraindication to hemodialysis, but it should be avoided in the following cases to avoid accidents: shock or hypotension, difficult to control bleeding, significant cardiac enlargement with severe myocardial damage, severe arrhythmia. Uncontrolled severe diabetes mellitus, cerebral hemorrhage, and elderly patients. Second, hemofiltration is a simulated device designed in accordance with the glomerular filtration function. Its characteristics are: 1. The removal of small molecules such as urea nitrogen and creatinine is slightly inferior to hemodialysis, but the removal of medium molecules, correction of water, electrolytes and acidosis, treatment of pulmonary edema, pericarditis and cerebral edema is better than hemodialysis. 2. The disadvantage is that the input of large amount of replacement fluid is easy to contaminate and cause fever reaction and sepsis. Continuous arteriovenous hemofiltration is to use the normal pressure gradient difference of arteriovenous pressure to continuously pass blood through a small filter to achieve the effect of hemofiltration. Its characteristics are: low filtration rate, no need to use hemofiltration machine and supplement a large amount of replacement fluid. Especially suitable for acute renal failure scene rescue. Blood perfusion is to introduce the patient’s arterial blood into the blood perfusion device stored with adsorbent material, so that the toxins and metabolites in the blood are adsorbed and purified through contact with the blood, and then re-infused into the body. Blood perfusion can effectively remove creatinine, uric acid, middle-molecular substances, phenols, guanidine, indoles, organic acids and many kinds of drugs from the blood, but it cannot remove water and electrolytes, so it should be used in combination with hemodialysis or hemofiltration in the treatment of uremia. Immunosorbent is a new technology developed in the past 20 years, which combines highly specific antigens, antibodies or certain substances with specific physicochemical affinity (ligands) with adsorbent materials (carriers) to make an adsorbent (column), using its specific adsorption properties to selectively or relatively specific removal of endogenous pathogenic factors in the patient’s blood, so as to achieve the purpose of blood purification and alleviation of disease. The main applications are It is mainly used in the following diseases: 1, severe systemic lupus erythematosus. 2, primary and recurrent focal segmental glomerulosclerosis. 3, anti-neutrophil cytoplasmic antibody-associated vasculitis. 4, neurological diseases: patients with myasthenia gravis have anti-acetylcholine receptor antibodies in their serum, which interfere with neuromuscular transmission and cause myasthenia gravis, immunosorbent can remove the antibodies and rapidly improve the symptoms of myasthenia gravis. 5. Dilated cardiomyopathy: A variety of different autoantibodies have been detected in patients with dilated cardiomyopathy: cardiac myosin antibodies, muscarinic M2 receptor antibodies, mitochondrial aconitine hydratase antibodies, etc. 6. It can be used in the treatment of various autoimmune diseases such as anti-glomerular basement membrane disease, lipoprotein nephropathy, Wegener’s granulomatosis, type II cryoglobulinemia, rheumatoid arthritis, immune thrombocytopenic purpura, hemolytic uremic syndrome/thrombotic thrombocytopenic purpura (HUS/TTP), anti-coagulation factor antibody-mediated coagulation abnormalities, etc. Plasma exchange is the introduction of the patient’s blood into the plasma exchange device, the separated plasma is discarded, and a certain amount of plasma is replenished in order to remove antibodies from the patient’s plasma and activate the mediators of immune response and immune complexes. The main applications are: ① immune complex glomerulonephritis and anti-glomerular basement membrane glomerulonephritis, such as pulmonary hemorrhage-nephritis syndrome, etc. rheumatic diseases and systemic lupus erythematosus, periarteritis nodosa and rheumatoid arthritis, etc. (iii) autoimmune hemolytic anemia, hemolytic uremic syndrome and thrombotic thrombocytopenic purpura, etc. ④Myasthenia gravis, Guillain-Barre syndrome. ⑤ Hepatic coma. (6) Mushroom poisoning. ⑦Severe psoriasis. ⑧Acute rejection reaction after renal transplantation. ⑨ hyperlipidemia. Seven, peritoneal dialysis is the use of peritoneal membrane as a semi-permeable membrane, according to the principle of multi-south membrane equilibrium, the prepared dialysis solution is instilled into the peritoneal cavity of patients through the catheter, through the solute concentration gradient difference between the two sides of the peritoneum, to achieve the purpose of removing metabolites, toxic substances and correcting water and electrolyte balance disorders in the body. The main indications are the same as those for hemodialysis. There are no absolute contraindications, but it is not recommended in the following cases: ① extensive peritoneal adhesions, trauma to abdominal viscera, recent major abdominal surgery, colostomy or fecal fistula, extensive abdominal wall infection or cellulitis, diffuse malignant tumor in the abdominal cavity or unknown lesions. ② diaphragmatic hernia, severe pulmonary lesions with respiratory distress. ③ Pregnancy.