Allergic Reactions to Contrast Media

PREVENTION OF GENERALIZED REACTIONS

RECOMMENDED PREMEDICATION

Corticosteroids:
• Prednisolone 30 mg orally
• Methylprednisolone 32 mg orally
Administration: 12 and 2 hours before contrast media.

IMPORTANT

Corticosteroids are not effective if administered less than 6 hours before contrast.

H1 and H2 Antihistamines can be used in addition to corticosteroids, but there is divided opinion about their preventive effectiveness.

GENERAL MEASURES FOR ALL PATIENTS

1. Have a crash cart with resuscitation medications in the examination room.
2. Observe patients for 20 to 30 minutes after contrast media injection.
3. Maintain venous access until patient discharge.

TECHNICIAN'S PERSONAL NOTE:
"Personally, I leave patients with the IV line in place until they are dressed and ready to leave, just in case anything happens."

EMERGENCY EQUIPMENT

FIRST-LINE MEDICATIONS AND INSTRUMENTS

Must be available in the examination room at all times:

Oxygen

Administration system

Epinephrine

1:1,000 for injection

H1 Antihistamine

Prepared for injection

Atropine

For bradycardia

COMPLEMENTARY EQUIPMENT

Inhaled ß-2 agonist

I.V. fluids (saline/Ringer's)

Anticonvulsants (diazepam)

Sphygmomanometer

One-way mouthpiece resuscitator

ACTION GUIDE FOR ACUTE REACTIONS

MILD-MODERATE

NAUSEA / VOMITING

Transient: Supportive treatment and observation.

Severe and prolonged: Consider administration of appropriate antiemetic.

MODERATE

URTICARIA

Widespread and transient: Supportive treatment with observation.

Widespread and prolonged: H1 antihistamine i.m. or i.v.
Marked: Epinephrine 1:1,000; 0.1-0.3 ml i.m. in adults.

SEVERE

BRONCHOSPASM

1. Oxygen (6-10 l/min)
2. Inhaled ß-2 agonist
3. Epinephrine according to blood pressure

With normal BP: 0.1-0.3 mg i.m.
With decreased BP: 0.5 mg i.m.

VERY SEVERE

LARYNGEAL EDEMA

1. Oxygen (6-10 l/min)
2. Epinephrine 0.5 mg i.m.
3. Repeat if necessary

Adults: 0.5 mg i.m.
Children: 0.01 mg/kg (max 0.3 mg)

CARDIOVASCULAR REACTIONS

ISOLATED HYPOTENSION

1. Elevate patient's legs
2. Oxygen (6-10 l/min)
3. I.V. fluids at rapid flow
4. If no response: Epinephrine 0.5 mg i.m.

HYPOTENSION + BRADYCARDIA (Vagal Reaction)

1. Elevate patient's legs
2. Oxygen (6-10 l/min)
3. Atropine 0.6-1.0 mg i.v.
4. I.V. fluids at rapid flow

Adults: Up to 3 mg total
Children: 0.02 mg/kg (max 0.6 mg/dose)

GENERALIZED ANAPHYLACTIC REACTION

1. Call emergency team
2. Airway suction if needed
3. Elevate legs if hypotensive
4. Oxygen (6-10 l/min)
5. Epinephrine 0.5 mg i.m.
6. I.V. fluids
7. H1 blockers i.v.

LATE ADVERSE REACTIONS

DEFINITION

A late adverse reaction to intravascular iodinated contrast media is defined as a reaction occurring from 1 hour to 1 week after contrast injection.

IMPORTANT CONSIDERATIONS

Many late symptoms (nausea, vomiting, headache, musculoskeletal pain, fever) described after contrast administration are not directly related to the contrast.

Skin reactions similar to other drug rashes are true late adverse reactions. They are usually mild to moderate and self-limiting.

RISK FACTORS FOR LATE CUTANEOUS REACTIONS

Previous Reaction

History of reaction to contrast media

Interleukin-2 Treatment

Specific immunotherapy

MANAGEMENT

Symptomatic and similar to management of other drug-induced cutaneous reactions.

PROPHYLAXIS

Not generally recommended, except in cases of previous severe reactions (oral steroids according to guideline 2.1).

PATIENT RECOMMENDATIONS

Inform patients who have had a previous reaction to contrast media or who are being treated with interleukin-2 about the possibility of late cutaneous reactions and that they should contact a physician if symptoms occur.

ALLERGIC REACTIONS TO CONTRAST MEDIA