What are the categories of acute adverse reaction to contrast agents?
Allergic-like reactions, rather than true allergies, are seen with radiographic contrast administration and are referred to as anaphylactoid reactions. These are not true hypersensitivity reactions, and immunoglobulin E (IgE) antibodies are not involved. The clinical manifestations may be similar to allergic reactions (such as hives or bronchospasm), but these reactions are often idiosyncratic and prior sensitization is not required, unlike with true allergies. These reactions are independent of the dose and concentration of the contrast agent. A history of prior allergic-like contrast reaction may indicate the need for corticosteroid premedication prior to future contrast-enhanced studies that utilize a similar contrast agent.
Physiologic reactions to contrast agents are associated with the dose, molecular toxicity, and physical and chemical characteristics of the contrast agent. A history of a prior physiologic contrast reaction does not indicate the need for future corticosteroid premedication.
Classification of Acute Contrast Reactions
| SEVERITY | ALLERGIC-LIKE | PHYSIOLOGIC |
|---|---|---|
| Mild: self-limited symptoms and signs | Limited urticaria/pruritus | Limited nausea/vomiting |
| Limited cutaneous edema | Transient flushing/warmth/chills | |
| Limited “itchy”/“scratchy” throat | Headache/dizziness/anxiety/altered taste | |
| Nasal congestion | Mild hypertension | |
| Sneezing/conjunctivitis/rhinorrhea | Vasovagal reaction that resolves spontaneously | |
| Moderate: more pronounced symptoms and signs, potentially becoming severe if untreated | Diffuse urticaria/pruritus | Protracted nausea/vomiting |
| Diffuse erythema, stable vital signs | Hypertensive urgency | |
| Facial edema without dyspnea | Isolated chest pain | |
| Throat tightness or hoarseness without dyspnea | Vasovagal reaction that requires and is responsive to treatment | |
| Wheezing/bronchospasm, mild or no hypoxia | ||
| Severe: often life-threatening, potentially resulting in permanent morbidity or death if not managed appropriately | Diffuse edema, or facial edema with dyspnea | Vasovagal reaction resistant to treatment |
| Diffuse erythema with hypotension | Arrhythmia | |
| Laryngeal edema with stridor and/or hypoxia | Convulsions, seizures | |
| Wheezing/bronchospasm, significant hypoxia | Hypertensive emergency | |
| Anaphylactic shock (hypotension and tachycardia) | Pulmonary edema Cardiopulmonary arrest | |
| Pulmonary edema | ||
| Cardiopulmonary arrest |
