Indocyanine Green (ICG) is a diagnostic dye used in various medical imaging and diagnostic procedures. Its fluorescent properties under near-infrared light allow medical professionals to visualize blood flow and assess organ function in real-time. ICG is employed in angiography to study blood vessels, in surgical procedures to enhance visibility of structures like bile ducts and tumors, and in tests to evaluate liver function and cardiac output.
ICG is administered intravenously and binds to proteins in the blood, limiting its diffusion out of blood vessels. The liver then exclusively removes the dye from circulation into the bile, with a half-life of about 150 to 180 seconds. These characteristics make ICG a valuable tool for understanding vascular health and tissue characteristics across different medical fields.
Common Reactions
After receiving Indocyanine Green, some individuals may experience mild and temporary reactions. Nausea is a frequently reported side effect that typically resolves without treatment. Some patients might also experience dizziness, which is short-lived.
Headaches are another common reaction, mild to moderate in intensity and subsiding within a few hours. Over-the-counter pain relievers can help manage this symptom effectively. A warm sensation or flushing may also occur, passing quickly.
Local reactions at the injection site are also possible, including pain, redness, or swelling. These minor reactions are not serious and resolve without intervention. Patients are advised to sit or lie down if they feel dizzy to help prevent falls or injuries.
Serious Reactions
While considered safe, Indocyanine Green can rarely cause severe reactions requiring immediate medical attention. Anaphylaxis, a severe allergic reaction, is a serious concern. Symptoms of anaphylaxis include difficulty breathing, swelling of the face, lips, tongue, or throat, and chest tightness.
Significant changes in blood pressure, including a sudden drop, or rapid and irregular heartbeats can also occur. In extreme cases, cardiac arrest has been reported, highlighting the need for close monitoring during and after ICG administration. Respiratory distress, including coughing, wheezing, or difficulty swallowing, represents another serious reaction.
Skin reactions, such as widespread hives or welts, can also indicate a serious allergic reaction. These severe reactions are uncommon, with an estimated incidence for anaphylaxis ranging from 0.05% to 0.07% of patients. Vigilance for these symptoms and prompt medical intervention are important for patient safety.
Who Should Be Cautious
Certain patient populations or conditions warrant caution with Indocyanine Green. Individuals with a known allergy to ICG or iodides should avoid its use due to anaphylaxis risk. Although the ICG molecule does not contain iodide, sodium iodide is added during manufacturing for stability, posing a risk for those with iodide hypersensitivity.
Patients with severe liver impairment should be cautious because ICG is exclusively cleared by the liver into the bile. While ICG is not considered nephrotoxic, caution is advised for patients with advanced chronic kidney disease or those undergoing hemodialysis. However, current research suggests ICG should not be withheld from patients with advanced chronic kidney disease or kidney transplants.
Individuals with certain thyroid conditions, particularly hyperthyroidism, should also be managed with caution. The sodium iodide content in ICG can potentially reduce the iodine-binding capacity of thyroid tissue for at least a week following administration. Patients should inform their healthcare providers about their complete medical history, including allergies or existing medical conditions, before ICG is administered.
What to Do if Side Effects Occur
If you experience any side effects after receiving Indocyanine Green, communicate with your healthcare provider immediately. For mild reactions such as temporary nausea, headache, or a warm sensation, these symptoms resolve on their own without specific treatment. However, if these symptoms persist or worsen, medical advice should be sought.
Symptoms that warrant immediate medical attention include difficulty breathing, swelling of the face, lips, tongue, or throat, and chest tightness. Other serious signs include a sudden drop in blood pressure, a rapid or irregular heartbeat, or any widespread skin reactions like hives or a severe rash. These could indicate a severe allergic reaction, such as anaphylaxis, which requires prompt medical intervention. Always inform your doctor or nurse about any unusual or severe symptoms you experience.