Preventing Kidney Injury Using Carbon Dioxide as Contrast Medium in Patients With Peripheral Arterial Disease (PAD) and Chronic Kidney Disease (CKD) Having Arterial Intervention

This research trial will test whether using carbon dioxide as a contrast medium during surgery to open blocked leg arteries can prevent kidney injury. One in five people over 55 in the UK suffer with narrowing or blockages in their leg arteries, which is called peripheral arterial disease. It leads to poor leg circulation, which can cause leg gangrene or infection. Sometimes this may even lead to major lower limb amputation. To prevent this from happening, the affected arteries can be opened using endovascular revascularisation. These procedures are the most common artery surgeries in the NHS. To be able to perform these procedures, doctors use an iodine-based contrast medium (dye) injected in the artery, which can negatively affect kidney function. Instead of the usual dye that causes kidney problems, carbon dioxide can be used as it does not damage the kidneys. No previous randomised controlled trial, however, has tested whether using carbon dioxide via automated injectors does indeed protect the kidneys in these procedures. This research will take place in at least six NHS hospitals in the UK. People with peripheral arterial disease and chronic kidney disease who are having a procedure to open their arteries will be asked to take part. Participants will be randomly chosen to have the procedure with carbon dioxide or with standard iodine-based contrast medium. The investigators will then perform blood tests to measure serum creatinine on the 2nd, 30th, and 90th day after the procedure to compare kidney function between the two groups. The investigators will also compare the volume of iodine-based contrast medium used. The study will also include qualitative research into how the hospital staff performing the intervention feel, as well as how participants found the procedure with carbon dioxide.

Inclusion Criteria: * Age \> 18 years * Undergoing any revascularisation with an endovascular component * Estimated glomerular filtration rate \