With the widespread use of contrast technology, contrast induced nephropathy (CIN) is increasingly seen in the clinical setting, especially after coronary intervention for cardiovascular disease. Contrast has become the third leading cause of nosocomially acquired acute renal failure. Therefore, how to prevent and treat CIN is an important issue that needs to be addressed. 1. Definition and morbidity In 2011, the European Society of Urological Radiology (ESUR) Contrast Safety Committee (CMSC) updated the 1999 Contrast Nephropathy (CIN) and developed a new guideline called Contrast Nephropathy. Definition: The new guidelines continue to use the 1999 CMSC diagnostic criteria for CIN: renal impairment (25% or 44umol/L increase in blood creatinine) within 3 days of intravascular contrast injection, except for other causes. The advantage is that the different tests can be compared effectively, and it is proposed that an absolute increase in creatinine is more relevant for the diagnosis of CIN than a relative increase. The incidence of CIN in the general population is 0.6%-6%, but in specific populations, such as the elderly, diabetic nephropathy, chronic kidney disease, chronic cardiac insufficiency, acute myocardial infarction, the incidence can be as high as 20% or more, and the incidence is as high as 40%-90% in people with multiple high-risk factors. The mechanism of contrast-induced renal damage is not well understood, and the possible pathogenesis of CIN is renal hemodynamic changes, renal medullary hypoxia, direct tubular toxicity of contrast agents, oxygen radical damage, immune factors and tubular obstruction. It is generally accepted that renal ischemia is the main pathogenesis of CIN, followed by tubular toxicity. Risk factors for CIN include patient factors and drug factors. Patient factors include underlying renal impairment, diabetes mellitus, advanced age, hemodynamic abnormalities (including hypovolemia, low hematocrit, congestive heart failure, hypotension, and aortic balloon counterpulsation), and drug factors include the type and dose of contrast media and the combination of other nephrotoxic drugs. Other factors include hypercholesterolemia, cirrhosis, sepsis, coronary artery bypass grafting, and prolonged coronary reperfusion. Mehran et al. established a scoring system for risk factors for CIN in 2004, in which eGFR < 20 ml/min/1.73 m2 was scored as 6, hypotension and chronic cardiac insufficiency as 5, age > 75 years as 4, diabetes mellitus and anemia as 3, and each additional 100 ml of contrast agent as 1. The risk of CIN was 26.1% and the risk of hemodialysis was 1.09% when the risk score was greater than 16, and the risk of CIN was 57.3% and the risk of hemodialysis was 12.6% when the risk score was greater than 16. 3.1 Renal insufficiency Renal impairment (Scr>132 mol/l or 1.5 mg/dl) is an independent risk factor for contrast nephropathy. The CIN Consensus Working Group concluded that: Scr levels ≥1. 0 mg/ dl in women and ≥1. 3 mg/ dl in men are associated with an increased risk of CIN. patients with CKD stages 3b, 4, 5 and eGFR.