From the Guidelines
A contrast allergy causing shortness of breath (SOB) can last for varying durations, typically resolving within 30 minutes to a few hours with appropriate treatment, but may persist for several hours or longer in moderate to severe reactions. The duration of shortness of breath due to a contrast allergy depends on the severity of the reaction. According to the study by 1, anaphylaxis, which can be caused by a contrast allergy, is characterized by sudden respiratory symptoms and signs, such as shortness of breath, wheeze, cough, stridor, and hypoxemia.
Severity of Reaction and Duration of SOB
- Mild reactions: shortness of breath may resolve within 30 minutes to a few hours with appropriate treatment, such as administering oxygen and providing medications like diphenhydramine (25-50mg IV/PO) or methylprednisolone (125mg IV) 1.
- Moderate reactions: may persist for several hours, requiring close monitoring and potentially additional treatment, such as epinephrine (0.3-0.5mg IM of 1:1000 solution) for severe reactions 1.
- Severe reactions: can last 24-48 hours or longer if not promptly treated, and may require hospitalization, as stated in the study by 1.
Management and Monitoring
Initial management includes stopping contrast administration, administering oxygen, and providing medications as needed. Patients experiencing contrast-related shortness of breath should be monitored until symptoms resolve completely. The mechanism involves either an anaphylactic IgE-mediated response or a non-allergic anaphylactoid reaction where contrast directly triggers mast cell and basophil degranulation, releasing histamine and other inflammatory mediators that cause bronchospasm and respiratory symptoms 1.
Risk of Biphasic Anaphylaxis
It is essential to consider the risk of biphasic anaphylaxis, which can occur in patients with a history of severe anaphylaxis or those who require multiple doses of epinephrine, as stated in the study by 1. Patients with severe reactions may require extended observation, up to 6 hours or longer, including hospital admission, to monitor for potential biphasic reactions. The study by 1 emphasizes the importance of educating patients about the risk of biphasic reactions and providing self-injectable epinephrine for prompt treatment if needed.
From the Research
Contrast Allergy and Shortness of Breath (SOB)
- The relationship between contrast allergy and shortness of breath (SOB) is not explicitly stated in the provided studies, but hypersensitivity reactions to contrast media can cause respiratory symptoms, including SOB 2, 3.
- Immediate reactions to contrast media can occur within the first hour after administration and may include symptoms such as erythema, urticaria, angioedema, and anaphylaxis, which can cause SOB 2, 3.
- Nonimmediate reactions can occur from more than 1 hour to several days after administration and may include symptoms such as maculopapular rash, but respiratory symptoms like SOB are less common in nonimmediate reactions 2.
- The management of severe allergic-like contrast media reactions, including those with respiratory symptoms like SOB, involves prompt recognition and treatment with intramuscular epinephrine autoinjectors and other supportive care measures 4.
- Patients with a history of hypersensitivity reactions to contrast media should undergo skin testing to identify an allergic mechanism and alternative agents for future procedures, and premedication may be necessary to prevent breakthrough reactions 5, 6.