Рентгенографічні контрастні речовини та контрастні реакції

Reactions vary in severity:

• Mild (eg, cough, itching, nasal congestion)

• Moderate (eg, dyspnea, wheezing, slight changes in pulse or blood pressure)

• Severe (eg, respiratory distress, arrhythmias such as bradycardia, seizures, shock, cardiopulmonary arrest)

The mechanism is anaphylactoid (see Anaphylaxis); risk factors include the following:

• A previous reaction to injected contrast agents

• Asthma

• Allergies

Treatment begins by stopping contrast infusion.

For mild or moderate reactions, diphenhydramine 25 to 50 mg IV is usually effective.

For severe reactions, treatment depends on the type of reaction and may include oxygen, epinephrine, IV fluids, and possibly atropine (for bradycardia).

In patients at high risk of contrast reactions, imaging tests that do not require iodinated contrast should be used. If contrast is necessary, a nonionic agent should be used, and patients should be premedicated with prednisone (50 mg orally 13 hours, 7 hours, and 1 hour before injection of contrast) and diphenhydramine (50 mg IV, IM, or orally 1 hour before contrast administration). If patients require imaging immediately, they can be given diphenhydramine 50 mg IV, IM, or orally 1 hour before injection of contrast and hydrocortisone 200 mg IV every 4 hours until the study is performed, preferably deferring imaging, if possible, until at least 2 doses of hydrocortisone have been administered (see American College of Radiology Manual on Contrast Media).

In contrast-induced nephropathy, serum creatinine typically begins to increase within 24 hours after administration of IV contrast; it peaks between days 3 and 5 and returns to baseline within 7 to 10 days.

Common risk factors include the following:

• Preexisting renal insufficiency (elevated creatinine)

• Diabetes mellitus, especially in patients with associated chronic kidney disease

• Hypertension

• Heart failure

• Multiple myeloma

• Age > 70

• Use of other nephrotoxic drugs

• Dehydration

In patients at risk of acute kidney injury after receiving iodinated intravascular contrast, the following measures should be considered:

• A reduced dose of contrast

• Use of an iso-osmolar agent

• Hydration

Many hydration regimens exist. One regimen suggests administration of normal saline at 100 mL per hour for a duration of 6 to 12 hours before the contrast administration and continued for 4 to 12 hours following the contrast injection (see American College of Radiology Manual on Contrast Media).

Administration of N-acetylcysteine has been widely studied and has not been shown to be effective in preventing contrast-induced nephropathy (1).

Patients who are taking metformin and develop acute kidney injury from contrast administration are at risk for lactic acidosis. If the patient has chronic kidney disease with an eGFR < 30 mL/min/1.73 m², already has acute kidney injury, or is undergoing arterial catheterization with a risk of emboli to the renal arteries, metformin should be withheld for 48 hours after contrast administration, and only resumed if kidney function is evaluated and deemed satisfactory. Metformin itself does not pose a risk for the development of contrast-induced nephropathy (see American College of Radiology Manual on Contrast Media).

Because many protocols dealing with contrast agents and reactions are specific and continually updated, it is important to discuss such details with the imaging department.

1. 1. Weisbord SD, Gallagher M, Jneid H, et al: Outcomes after Angiography with Sodium Bicarbonate and Acetylcysteine. N Engl J Med 378(7):603-614, 2018. doi:10.1056/NEJMoa1710933