From the Guidelines
Patients with contrast allergies should be monitored for at least 4-6 hours after a reaction, and those with severe reactions should be considered for extended observation or hospital admission. Upon discharge, patients with significant reactions may benefit from a short course of oral antihistamines, such as diphenhydramine 25-50mg every 6 hours or cetirizine 10mg daily, for 24-48 hours, and a 3-day course of oral corticosteroids, such as prednisone 40-60mg daily, may be prescribed for moderate to severe reactions 1. The decision to discharge a patient should be based on the severity of the reaction, the patient's response to treatment, and the presence of risk factors for biphasic anaphylaxis, such as a history of severe anaphylaxis, unknown anaphylaxis trigger, or multiple doses of epinephrine 1. Key considerations in management include:
- Monitoring for at least 4-6 hours after a reaction to detect potential biphasic anaphylaxis
- Providing education on anaphylaxis recognition, epinephrine auto-injector use, and follow-up care
- Considering extended observation or hospital admission for patients with severe reactions or risk factors for biphasic anaphylaxis
- Prescribing oral antihistamines and corticosteroids as needed for symptom management and prevention of rebound reactions. It is essential to weigh the benefits of extended observation against the potential risks and costs, and to consider shared decision-making with patients and their families 1.
From the Research
Management of Contrast Allergy
- The management of contrast allergy involves premedication with corticosteroids and anti-histamines, as well as the selection of an optimal contrast agent 2.
- In cases of severe allergy, rapid desensitization to iodinated contrast media can be achieved by administering progressively incremental doses of the media 2.
- The use of intramuscular epinephrine autoinjectors is recommended whenever a severe allergic-like reaction is suspected 3.
Monitoring and Discharge
- Patients who have experienced a contrast allergy should be monitored for a period of time after the procedure to ensure that no further reactions occur 3.
- The exact duration of monitoring is not specified in the available studies, but it is recommended that patients be closely observed for at least several hours after the procedure.
- Patients may be discharged on medication, such as corticosteroids and anti-histamines, to prevent further reactions 4, 5.
- The use of a different contrast agent may also be considered in patients who have experienced a previous allergic-like reaction 5.
Prevention of Repeat Reactions
- The use of steroid premedication and contrast material substitution can help prevent repeat allergic-like reactions in high-risk patients 5.
- A study found that patients who received a different iodinated contrast material with and without steroid premedication had a significantly lower rate of repeat reactions than those who received steroid premedication and the same contrast material 5.
- Emergency pretreatment with intravenous steroids and H1 and H2 blockers may also be effective in preventing adverse reactions in patients with a previous contrast reaction who require emergency coronary angiography 6.