Contrast agent (contrast medium) is a drug commonly used in angiography and balloon angioplasty (PTA: percutaneous transluminal angioplasty). It clearly shows the lesions where vessels are narrowed, so that balloon angioplasty or stent placement can then be performed.
Some dialysis patients are allergic to contrast agent by constitution, or gradually develop an allergic reaction after repeated angiograms.
Contrast agent then cannot be used for angiography. Without it, diagnosis and treatment may be limited, because the narrowed segments cannot be clearly identified for further treatment.
Common symptoms and reactions of contrast allergy include: local skin rash / itching / hives, skin redness and swelling, nausea and vomiting, cold-like symptoms, chills and fever, headache and dizziness and others. Mild symptoms usually go away on their own. In some patients the reaction becomes more pronounced with each contrast angiogram. In severe cases there may even be an allergic shock reaction.
To avoid allergic reactions to contrast agent while still being able to clearly find the narrowed segments on the angiogram, CO2 (carbon dioxide) angiography offers a solution.
When CO2 angiography is used:
- Patients who are allergic to contrast agent
- People with poor kidney function (to reduce the harm of contrast agent to the kidneys)
Contraindications to using CO2:
- Must not be used for angiography of the cerebral arteries, coronary arteries or thoracic arteries
- Must not be performed in the prone position, as it may cause spinal cord ischemia
- Patients with COPD (chronic obstructive pulmonary disease)
- The arterial inflow end of the dialysis access
- Anesthesia with nitrous oxide (N2O)
For patients who are allergic to contrast agent, Dr. Su’s team now offers CO2 angiography at the vascular center, to avoid the allergic reactions that contrast agent may cause.
