Adverse reactions to radiographic contrast material.

Major adverse reactions to radiographic contrast media will occur more often as contrast material is now also administered during computerized tomographic (CT) scanning. Differentiation of the two major contrast reactions, the vagus reaction and the anaphylactoid reaction, is essential. Bradycardia is the key finding for identifying the vagus reaction. The vagus reaction involving hypotension and bradycardia requires treatment with large doses of atropine given intravenously. The immediate generalized reaction or anaphylactoid reaction should be treated as anaphylaxis with administration of vasopressors, fluids, steroids and antihistamines. Steroids and antihistamines given before the examination may offer protection to those high-risk patients who have had previous anaphylactoid reactions to contrast material.