Peripheral arterial disease (PAD) commonly coexists with chronic kidney disease (CKD). Patients with symptomatic PAD often require endovascular revascularisation to relieve pain or salvage limbs. However, the iodinated intra-arterial contrast routinely used in these procedures is nephrotoxic, placing patients with CKD at increased risk of acute kidney injury (AKI) and long-term renal decline. Carbon dioxide (CO₂) delivered via automated injection is a potential alternative imaging contrast medium. This trial will evaluate whether using CO₂ instead of iodinated contrast reduces the risk of AKI and short-term renal function decline in this high-risk group.

This is a multicentre, open-label, prospective randomised controlled trial across six secondary-care National Health Service (NHS) vascular surgery centres. A total of 174 patients with PAD and CKD undergoing endovascular intervention will be randomised 1:1 to receive iodinated contrast (standard of care) or CO₂ via automated injector (Angiodroid). All perioperative care will follow local NHS protocols.

The primary outcome is log serum creatinine at 2, 30 and 90 days postprocedure. Key secondary outcomes include: incidence and severity of AKI within 48 hours postprocedure, major adverse kidney events (death, dialysis or >25% estimated glomerular filtration rate decline) by 90 days, inpatient length of stay, procedural pain, quality of life, procedural success, reinterventions, acceptability and feasibility (patient/practitioner questionnaires) of using CO₂, and cost-effectiveness (healthcare resource use analysis). A mixed-methods process evaluation will be undertaken with patients and clinicians.

The trial has been approved by an NHS ethical review committee (24/WA/0332) and patients have been involved in trial design. Findings will be disseminated to participants, clinicians and the wider public through patient groups, lay summaries, social media, conferences, peer-reviewed journals and NHS policy channels.

ISRCTN23564393.