The Common Vein

The Common Vein Copyright 2008

 Elizabeth Beeuwkes Baker, TUSM IV

Ashley Davidoff MD

Definition

Contrast induced nephropathy (CIN) is an iatrogenic disorder caused by the use of iodinated contrast material resulting in  a creatinine increase of more than 25% or more than 0.5 mg/DL occurring 48 to 72 hours after administration of IV contrast, in the absence of other obvious causes.   Though the effect is transient, it can significantly increase morbidity and mortality.

 

Factors that put a patient at high risk for RCN include intravascular volume depletion, chronic renal failure, diabetes, and a high dose of CM, congestive heart failure and advanced age.

Other factors that increase the risk include higher doses of contrast, tand he use of high-osmolar agents.  The latter are rarely used today and most agents used now are iso-osmolar or low-osmolar

 

CIN is associated with cardiovascular complications, longer hospitalization, and higher mortality.

It is the third most common cause of new acute renal failure in hospitalized patients.

 

Treatment is conservative and includes hydration but more important are  prevention regimens

 

What prophylaxis should be used?

 

A three-prong approach:

1) Aggressive IV hydration ? two options:

1. a) Isotonic saline: (1mL/kg/h) starting 4 to 6 hours before CM administration and continued for several hours afterwards.

b)Isotonic Alkalizing solution: 154 mEq/L sodium bicarbonate in dextrose and H2O.  Use a rate of 3mL/kg/h for 1 hour before and 1mL/kg/h during the procedure and for 6 hours after the procedure.

2) Choice of contrast agent ? Use nonionic low osmolar or iso-osmolar CM

3) Treat with  N-Acetylcysteine (NAC, Mucomyst)

600mg or 1200mg orally twice daily on the day before and the day of the procedure for a total of two days.

 

WHY?

 

1) Hydration ? Patients who are depleted in intravascular volume are at high risk for Radiocontrast Nephropathy (RCN).  This is possibly due to higher concentrations of toxins in the renal tubule plus prolonged exposure to such substances.  Use of a sodium bicarbonate isotonic solution for hydration has been shown to further reduce the risk of RCN.  This may be due to reduction of free radical formation with an increase in urine pH.

 

2) Nonionic low or iso-osmolar contrast medium ? has been shown to reduce risk of RCN in patients with renal impairment.  Some studies also show a benefit of iso-osmolar over low-osmolar with regard to renal impairment, perhaps due do decreased osmotic diuresis.

 

3) Prophylaxis with N-acetylcysteine ? Contrast media induces renal vasoconstriction, while N-acetycysteine induces renal vasodilation.  NAC also may scavenge oxygen free radicals and attenuate endothelial dysfunction.

References:

 

Giancarlo Marenzi and Antonio L. Bartorelli: Recent advances in the prevention of radiocontrast-induced nephropathy. Curr Opin Crit Care 2004, 10:505-509

 

Kelly A.M., Dwamema B., Cronin P., et al. ?Meta-Analysis: Effectiveness of Drugs for Preventing Contrast-Induced Nephropathy.? Ann Intern Med 2008; 148:284-294.

 

Tepel M, van Del Giet M, Schwarzfeld NR, et al,: Prevention of readiographic-contrast-agent-induced reductions in renal function by acetycysteine. N Engl J Med 2000, 343:180-184