Contrast nephrotoxicity: acute renal failure occurring within 2-5 days of the procedure, due to nephrotoxic effects of contrast dyes. It is especially common in patients with preexisting chronic renal insufficiency and diabetes mellitus ( 60% incidence when 30 ml of dye was used).
Atheroembolic renal disease: mechanical disruption of aortic atheroma by the catheter and subsequent microembolization into the kidneys. Clinically, it is characterized by a sudden or slow increase in serum creatinine level, which is usually not completely reversible and occasionally may be associated with eosinophilia, thrombocytopenia, and transient decreases in serum complement levels. Urinary abnormalities may range from benign sediment to hematuria, proteinuria, eosinophiluria, or red cell casts. Embolization to other organs may occur (e.g., livedo reticularis, peripheral cyanosis, bowel ischemia).
What precautions can be taken to prevent or minimize contrast nephrotoxocity?
Recognize high-risk individuals prone to this complication (i.e., those with diabetes mellitus and chronic renal insufficiency).
Volume replete, because hypovolemic patients are at much higher risk. In patients without congestive heart failure or overt signs of volume excess, diuretics should be stopped at least 1-2 days before the procedure, and intravenous fluids should be started several hours before the test.
Intravenous mannitol, 25 g given before and after the procedure, may be protective. Monitor intake and output closely, and avoid negative fluid balance with mannitol diuresis. Mannitol is contraindicated in patients with severe renal insufficiency, in whom it can cause pulmonary edema secondary to the osmotic effect of mannitol.
Do nonionic, low-osmolality contrast media cause less contrast nephrotoxicity than conventional high-osmolality contrast media?
A lower adverse reaction profile of low-osmolality agents has been suggested, but there is no convincing evidence for decreased nephrotoxicity from controlled randomized human studies. Because these agents are about 20 times more expensive than the conventional high-osmolality agents, their routine use is not justified in the absence of clear evidence of a lower side effect profile.
What are the lipid abnormalities associated with renal disease?
‚ In nephrotic syndrome, elevation of total and low-density lipoprotein (LDL) cholesterol is a result of increased hepatic synthesis of lipoprotein B, most likely due to hypoalbu-minemia. The hypercholesterolemia is usually severe.
‚ In chronic renal failure, hypertriglyceridemia is seen in 30% of patients. The defect may be due to the reduced lipolysis of triglyceride-rich lipoproteins (mainly very-low-density lipoproteins, VLDL).