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Radiology.Academy.Sk

Contrast

Risk Factors for Reactions:

- Allergy: a history of a prior allergy-like reaction to contrast is associated with an up to five fold increased likelihood of the patient experiencing a subsequent reaction.
- Atopy: 3 times likelihood of reaction
- Asthma: increased likelihood of reaction
- Renal insufficiency: CIN [Contrast Induced Nephrotoxicity], NSF [Nephrogenic Systemic Fibrosis]
- Cardiac status
- Anxiety, Age, paraproteinemia,

Informed consent is not necessary before all contrast media injections unless higher risk.

Contrast agents can be safely used in patients with previous allergiclike reaction to contrast, but special care must be taken to be aware of what the previous reaction was and to be ready to treat any reaction. Pre-treatment with steroids with or without antihistamines prevent minor reactions but may not be able to prevent major reaction.

Allergy to shellfish has no association with iodine contrast agents - may be used safely in patient with such condition.

Contrast agent induced nephropathy: Occurs only in patients with underlying renal dysfunction. Obtain Cr in all at risk patients and calculate Cr clearance.

Major RF:
- DM 2
- dehydration (major surgery, cardiogenic shock)
- nephrotoxic medications (gentamycin, NSAIDs)
- renal stones, UTIs, BPH.

Prevention:
- Prednisone 50mg q6h x 3 prior study or 40mg prednisolone q4h IV
- Diphenhydramine 50mg PO, IV or IM 1h prior study (decrease urticaria, angioedema, and respiratory symptoms)
- adequate PO or IV hydration (1ml/kg/h of NS)
- N-acetylcystein

Use of metformin and an iodinated contrast agent could lead to an increased risk of lactic acidosis. Therefore, metformin should be stopped at the time an iodinated contrast agent is administered and that the patient should wait 48 hours before resuming use of metformin. Metformin is contraindicated in patients with any compromise in renal function (high concentration = lactic acidosis).

Extravasated contrast can cause Compartment syndrome.

Contrast has been safe in pregnancy and breastfeeding but caution has been adviced. The risk must be balanced against the possible benefits. Do not use unless necessary. Breast-feeding can restart 24 hours after contrast administration. Discard pumped milk.

Moderate reactions:
- SOB
- Cardiaclike sy
- Laryngeal edema
- Facial edema
- Bronchospasm
- Rigors
- Hypotension
- Diaphoresis
- Tongue swelling
- Hypertension

Mild Allergiclike reactions:
- Urticaria, Pruritus, Erythema or rash
- Scratchy throat, Nasal congestion, Sneezing
- Facial swelling
- Chest discomfort, Transient cough
- Rigors or chills
- Tachycardia or palpitations
- Thickened tongue
- Injected eye

Management:
- O2 by face mask (10-15L/min)
- Hydration IV or PO
- Diphenhydramine 50mg IV, PO (do not give it to hypotensive pt)
- Albuterol INH
- Epinephrine 0.1mg-0.3mg IV
- Nitroglycerin SL
- Corticosteroids: 125mg methylprednisolone IV; caution in patients with uncontrolled hypertension, diabetes, tuberculosis, systemic fungal infections, peptic ulcer disease or diverticulitis