What is the steroid preparation for contrast media allergy?

From the Guidelines

For patients with a history of contrast allergy, a steroid premedication regimen is recommended to reduce the risk of allergic reactions, as stated in the 2011 ACCF/AHA/SCAI guideline for percutaneous coronary intervention 1. The standard protocol consists of oral prednisone 50 mg given at 13 hours, 7 hours, and 1 hour before contrast administration, along with diphenhydramine (Benadryl) 50 mg orally or intravenously 1 hour before the procedure. Some key points to consider:

• The incidence of anaphylactoid reactions to contrast media is 1%, and the incidence of severe reactions may be as low as 0.04% 1.
• In patients with a history of prior anaphylactoid reaction, the recurrence rate without prophylaxis is in the range of 16% to 44%, but adequate pretreatment reduces the recurrence rate to close to zero 1.
• For emergency situations where the full 13-hour protocol isn't feasible, an accelerated regimen can be used: methylprednisolone 40 mg or hydrocortisone 200 mg intravenously every 4 hours until contrast administration, plus diphenhydramine 50 mg given 1 hour before the procedure.
• It's essential to note that premedication reduces but doesn't eliminate the risk of reactions, so using the lowest necessary dose of contrast media and having emergency medications readily available during the procedure remains essential.
• Patients should be monitored for at least 30 minutes after contrast administration, even with premedication.
• There are no data to suggest that those patients with seafood or shellfish allergies are at risk for an anaphylactoid reaction from exposure to contrast media, and premedication based only on a history of seafood or shellfish allergy has a small but non-zero risk of adverse effect without any demonstrated benefit 1.

From the Research

Steroid Prep for Contrast Allergy

• The use of corticosteroid prophylaxis for preventing acute allergic-like reactions to iodinated contrast media is still controversial, with no strong evidence supporting its efficacy before administration of nonionic low osmolar contrast media (LOCM) 2.
• A retrospective study found that premedication with corticosteroids seems to be helpful in reducing the overall rate of recurrence of acute allergic-like reactions to LOCM in high-risk patients, but patients with severe index reactions are still at risk of developing severe reactions despite corticosteroid premedication 2.
• Identifying patients at high risk for an "allergy-type" reaction to contrast media is an essential task, and prevention of or reduction of the risk of an adverse reaction is critical to patient safety 3.
• A study compared the effectiveness of ICM substitution with 12- and 2-hour steroid premedication for preventing repeat acute allergic-like reactions in high-risk patients, and found that using an iodinated contrast material (ICM) substitution was more effective for preventing repeat allergic-like reactions than using steroid premedication and the same ICM that caused the previous reaction 4.
• Pretreatment with prednisone plus diphenhydramine or prednisone and diphenhydramine plus ephedrine decreased the reaction rate to 9.0% and 3.1%, respectively, during 657 procedures in 563 patients 5.
• However, there have been cases of anaphylactoid reaction after retrograde pyelography despite preoperative steroid preparation, highlighting the importance of emergency equipment being available for all procedures 6.

Key Findings

• Corticosteroid premedication can reduce the overall rate of recurrence of acute allergic-like reactions to LOCM in high-risk patients 2.
• ICM substitution may be more effective than steroid premedication for preventing repeat allergic-like reactions 4.
• Pretreatment with prednisone plus diphenhydramine or prednisone and diphenhydramine plus ephedrine can decrease the reaction rate 5.
• Emergency equipment should be available for all procedures, as anaphylactoid reactions can still occur despite preoperative steroid preparation 6.