Allergic reactions to iodinated contrast media: premedication considerations for patients at risk

Abstract

The objectives of this article are to review allergy-type reactions to iodinated contrast media and the protocols utilized to prevent or reduce the occurrence of these adverse reactions in high-risk patients. We will begin by discussing the types or classifications of the adverse reactions to iodinated contrast media. We will then discuss reaction mechanisms, identify the patients at highest risk for adverse reactions, and clarify common misperceptions about the risk. Finally, we will discuss the actions of the medications used to help reduce or prevent allergy-type reactions to iodinated contrast media, the protocols used to help reduce or prevent contrast reactions in high-risk patients, and the potential side effects of these medications. We will also discuss the high-risk patient who has received premedication due to a prior index reaction and discuss the risk of having a subsequent reaction, termed "breakthrough reaction." Identifying patient at high risk for an "allergy-type" reaction to contrast media is an essential task of the radiologist. Prevention of or reduction of the risk of an adverse reaction is critical to patient safety. If an examination can be performed without contrast in a patient at high risk for an allergy-type reaction, it may be appropriate to avoid contrast. However, there are situations where contrast media is necessary, and the radiologist plays a vital role in preventing or mitigating an allergy-type reaction.

Risco de reação adversa ao meio de contraste iodado: um estudo de validação

“…In this sense, the opinion of the experts agrees with literature, which also refers to these two outcomes as the most preoccupying (1)(2)(4)(5)(6)(7) . It is notable that a previous history of adverse reaction to iodinated contrast increases the chance of a new event up to seven times, in comparison with non-reagent individuals (4) .…”

“…Chemotoxic reactions manifest as nausea, vomiting, cardiac arrhythmia, hypertension, seizures, renal failure, and vasovagal reactions, amongst others. Localized events such as phlebitis, thrombophlebitis or lesions caused by extravasation of the radiopaque media can also occur (1)(2)(3)(4)(5)(6)(7) . The nursing team that attends in Imaging Diagnostic Services (IDS) and associated areas plays a crucial role in the prevention of events related to iodinated contrast media since they participate in the preparation of patients, carry out tests, administer the radiopaque media, and manage post-procedure recovery.…”

Clinical Practice Guidelines for Diagnosis and Management of Hypersensitivity Reactions to Contrast Media

“…It has only been shown to reduce the occurrence of mild immediate reactions and has not been demonstrated to be useful for immediate moderate to severe and nonimmediate reactions [46,94,95].…”

Risk Factors in Fatal Cases of Anaphylaxis due to Contrast Media: A Forensic Evaluation

“…Nonmediated reactions to radiocontrast media, occurring >1 h after administration, mainly consist of skin manifestations. Most of these appear to be allergic reactions mediated by T cells, demonstrated by (1) the frequently reported positive patch tests and delayed intradermal tests to the culprit contrast medium in previous reactors, (2) the presence of dermal infiltrates of T cells in the affected skin areas, (3) the reappearance of the eruption after provocation testing, and (4) the ability of the contrast medium to stimulate the proliferation of peripheral T cells from patients with contrast medium-induced skin eruptions [8,9,10,13,16,17,18,19,20]. …”

“…These are both contrast medium-related, concerning the type, dose and route of administration, and patient-related, pertaining to age, gender, previous exposure to contrast compounds, previous adverse reactions to contrast media, some medications and allergic (asthma, allergic rhinitis, atopic dermatitis, a history of multiple allergies, drug allergy and food allergy) and nonallergic (cardiovascular, renal, hematologic, autoimmune and metabolic conditions) diseases [1,12,16,19,23,24,25,26]. …”