Older hypertonic, hyperosmolar, ionic contrast media are especially associated with intravascular volume problems, such as initial hypervolemia followed by diuresis and dehydration. Because these substances contain iodine to increase their density, allergies to iodine and shellfish may predispose to a contrast reaction.
Severe reactions can occur when administering protamine.
A diabetic on protamine insulin may have an increased risk of developing a protamine reaction. In order to avoid bleeding complications during these invasive procedures, the coagulation system must be evaluated preoperatively, particularly in patients taking anticoagulants. Oral anticoagulants should be stopped at least 48 hours prior to the procedure. Optimal anesthetic management aims to avoid extremes of glucose concentration, since both hyperglycemia and hypoglycemia have a negative impact. In view of the potential for neurologic injury in INR, blood sugar must be closely monitored and controlled perioperatively in these patients.