CT/X-Ray Contrast Media
Situations where iodinated contrast agents should be used with caution: lung and heart diseases, catecholamine secreting tumours, pregnant and lactating women, myeloma and macroglobulinemia, myasthenia gravis, homocystinuria.
Contraindication: uncured patients with hyperthyroidism.
Dose limit for iodinated contrast agents
On the premise of satisfying imaging/diagnosis, the minimum dose of iodinated contrast agents should be used.
For low-risk patients, the total dose of types of contrast agents had better be controlled within 300 ~ 400 ml.
Maximum dose of iodinated radiocontrast dye
Method I *: 5 ml × body weight (kg)/serum creatinine (mg/dl) (not more than 300 ml) [refer to Cigarroa calculation formula]
Method II: 3.7 times creatinine clearance [according to 2011 ACCF/AHAUA/NSTEMI Treatment Guidelines]
For those with severe renal insufficiency, try to choose an imaging method that does not require iodine-based contrast agents or a non-imaging method that can provide sufficient diagnostic information.
Avoid repeated use of the diagnostic dose of an iodinated contrast medium in a short period of time. If repeated use is indeed necessary, it is recommended that the interval between two MRI contrast agent applications be ≥14 days.
Other precautions for the use of iodinated contrast agents
Preheating: Before using an iodinated contrast agent, it is recommended to heat the contrast agent to 37 °C and place it in a thermostat.
Hydration: It is recommended to hydrate patients within 6 to 12 hours before using an iodinated contrast agent to within 24 hours after use. Hydration method: Intra-arterial drug users are advised to receive intravenous rehydration and oral rehydration concomitantly, and oral rehydration is recommended for intravenous drug users.
Stay and observation: After the injection of the iodine-based contrast media, the patient needs to stay and be observed for 30 minutes before leaving the examination room.
Establish an emergency channel: Establish an emergency rapid support mechanism for the rescue of adverse reactions caused by iodinated contrast agents with the emergency room or other clinical related departments to ensure that after an adverse reaction occurs, clinicians can promptly rush to the rescue scene for rescue if necessary.
Prevention and Management of Vascular Extravasation of Iodinated Contrast Agents
Prevention
Choose appropriate blood vessels for venipuncture and operate carefully; when using a high-pressure syringe, choose a puncture needle and catheter that match the injection flow rate; properly fix the puncture needle; communicate with the patient and get cooperation.
Management
Mild extravasation: Most injuries are minor and need no treatment. However, the patient should be instructed to keep observing. If the extravasation worsens, the patient should seek medical attention in time. For individuals with significant pain, common cold and hydropathic compresses can be given locally.
Moderate and severe extravasation: ① raise the affected limb to promote blood return. ② Use 50% magnesium sulfate moisturizing cold compress in the beginning, and after 24-hours change to magnesium sulfate moisturizing hot compress, or use mucopolysaccharide ointment for topical application, or use 0.05% dexamethasone for local hydropathic compress. ③ Those with severe contrast agent extravasation should be given oral dexamethasone 5 mg/time tid for 3 consecutive days on the basis of topical drug use. ④ If necessary, consult a clinician for medication.
