Improve safety with IV contrast agents

Check renal function. With GADOLINIUM orders, look for patients with an eGFR below 30 mL/min, with acute kidney injury, or on dialysis....
Abdelwahab Ward, BS Pharm, PharmD

As a hospital pharmacist, you will field questions about the safe use of IV contrast. Think of IV contrast as two classes that aren’t interchangeable...

  • Gadolinium-based contrast (Magnevist, Omniscan, etc) is often used for MRI, and
  • Iodine-based (Omnipaque, Ultravist, Visipaque, Optiray, etc) for CT.

Evaluate allergies. Iodine-based contrast reactions are NOT cross-reactive with gadolinium or with shellfish or povidone-iodine. When a general “IV contrast allergy” is listed, use electronic health record (EHR) records to try to determine the specific culprit and the date it occurred. Point out that the contrast agents we give now are less likely to cause adverse reactions than previous ones that we no longer use.

Advise that it’s okay to use an agent from the same class if a previous reaction wasn’t severe (anaphylaxis, arrhythmias, etc). But if it was severe, evaluate the benefit and risk. Ensure treatment (epinephrine, etc) is available in these situations, (see table 1).

Responsive Tables
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Table 1. Recommended Treatment for Moderate to Severe Reactions to Contrast Agents in Adults.
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Table 2. Classification of Acute Reactions to Contrast Agents.
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Table 3. Elective and Emergent Premedication Protocols.
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Table 4. Association of GBCAs with NSF.

Clarify if the reaction was allergic-like (urticaria, pruritus, edema, etc) or physiologic (chest pain, headache, flushing, etc). For a previous allergic-like reaction, consider premedicating with corticosteroids and possibly an antihistamine, (see table 2). For physiologic reactions, don’t give premedications, they won’t help, (see table 3). Advise trying the lowest dose necessary, since these reactions are often dose-dependent.

Check renal function. With GADOLINIUM orders, look for patients with an eGFR below 30 mL/min/1.73 m2, with acute kidney injury, or on dialysis. In these patients, gadolinium can cause nephrogenic systemic fibrosis (NSF), a rare, but sometimes fatal, condition mostly affecting the skin. If gadolinium is essential, try to stick with Gadavist, or ProHance, these have little to no risk of NSF. Magnevist is associated with high risk of NSF, (see table 4). Be aware, nephropathy risk when giving IODINE-BASED contrast IV is lower than once thought, partly due to the phasing out of high osmolarity products (Gastrografin, Conray, etc) for CT.

Correct dehydration, if able, before using IV iodine-based contrast. Don’t rely on acetylcysteine or IV sodium bicarbonate for renal protection. Get our note, "Contrast-induced nephropathy prevention strategy".

References

Abdelwahab Ward, BS Pharm, PharmD