Ionic and nonionic contrast media

Ionic and nonionic contrast media are administered intravenously and intra-arterially to supplement imaging; complexed gadolinium may be administered for both MRI and x-ray–based imaging. Low-osmolality contrast media (hypo and iso osmolar) are preferred over high-osmolality contrast media as they are less nephrotoxic.

1. Contrast-induced nephropathy (CIN) is defined as a deterioration in kidney function as a result of intravascular contrast administration.
   1. Risk factors include pre­existing renal insufficiency (eGFR < 30) as well as diabetes and HTN. Cardiac angiography procedures are associated with a higher incidence owing to the nature of contrast injection.
   2. Baseline serum creatinine should be obtained in patients considered at risk.
   3. Precontrast IV volume expansion with crystalloid is the mainstay of prophylaxis for CIN. The ideal infusion rate and volume are unknown. Oral hydration has demonstrated less effectiveness. Other therapies do not have strong evidence, such as N-acetylcysteine and sodium bicarbonate.
2. Nephrogenic systemic fibrosis is a sclerosing skin condition that occurs after gadolinium exposure in patients with advanced or end-stage renal disease, with or without dialysis. This typically occurs days or months following exposure.