View source for Contrast induced allergic reaction

==Background==
*Approximately 75 million doses of iodinated contrast agents are given worldwide each year
*Many patients will report allergies to shellfish, iodine, or prior contrast infusions
*Prior allergic or [[anaphylactic reaction]] to contrast infusion (whether low osmolality or high osmolality) is a contraindication to future contrast administration

===Risk Factors===
*[[Asthma]] (most common)
*[[CHF]]
*[[Beta blocker]] use

==Clinical Features==
*Similar to [[Allergic Reaction]] - [[Anaphylaxis]] (depending on severity)
*[[Urticaria]]
*[[Pruritus]]
*Airway edema
*[[Shortness of breath]]
*[[Hypotension]]

==Differential Diagnosis==
{{Acute Allergic DDX}}

{{Contrast complications DDX}}

==Evaluation==
*Clinical diagnosis

==Management==
===Acute treatment===
*Treatment is similar to [[Anaphylaxis]]
*Administer IV fluids
*PO or IV [[steroid]]
*Nebulized [[albuterol]] or [[Epinephrine]] may be beneficial for airway edema
*[[Epinephrine]] should be administered for any signs of [[Anaphylaxis]]

===Prevention===
*Patients often report various allergies and there is controversy over the best way to prevent possible contrast induced allergic reaction

'''Shellfish Allergy'''
*This allergy is specific to shellfish and does not cross react due to the Iodine rich nature of fish and the fish's tropomyosins and parvalbumin<ref>Schabelman E, Witting M. The relationship of radiocontrast, iodine, and seafood allergies: a medical myth exposed. J Emerg Med. 2010 Nov;39(5):701-7.</ref>
*No pretreatment is necessary for shellfish allergies

'''Iodine'''
*There is no Iodine allergies which are compatible with life due to the existence of iodine in human thyroid tissue and distribution throughout the body

'''Prior Contrast Allergies'''
*Pretreatment should not be attempted in these patients since there is a strong association between a prior contrast reaction and future anaphylactic contrast reactions<ref name="Lasser">Lasser EC et al. Pretreatment with corticosteroids to pre- vent adverse reactions to nonionic contrast media. AJR AM J Roentgenol. 1994 Mar;162(3):523-6.</ref>

'''Pretreatment with Steroids'''
*There has been no difference found between ionic agents alone versus ionic agents with steroids in preventing allergic reactions.  Non ionic (low osmolality) contrast agents are the preferred agent and do reduce the risk of allergic reactions. <ref>Wolf GL et al. Comparison of the rates of adverse drug re- actions. Ionic contrast agents, ionic agents combined with steroids, and nonionic agents. Invest Radiol. 1991 May; 26(5):404-10</ref><ref name="Lasser"></ref>

==Disposition==
*Any contrast reaction that is mild such as pruritus or mild urticaria can be observed in the emergency room for recurrent reactions
*Severe anaphylactic reactions requiring multiple administrations of epinephrine should be admitted.
*Patients receiving a single dose of epinephrine should have clinical judgment applied as to observation or discharge
*'''All patients should be prescribed an [[Epinephrine]] Auto Injector regardless of disposition

==See Also==
*[[Anaphylaxis]]
*[[Contrast-induced nephropathy]]

==External Links==

==References==
<references/>

[[Category:Critical Care]]
[[Category:Radiology]]