Could carbon dioxide replace contrast dye to save kidneys?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Symptomatic peripheral arterial disease presenting with either acute symptoms (Rutherford clinical categories I-IIb) or chronic symptoms (Fontaine stages IIb-IV or Rutherford clinical categories 2-6) 2. Planned peripheral vascular intervention of infrainguinal arteries due to femoropopliteal and/or infrapopliteal lesions 3. Increased risk of CA-AKI identified by a baseline risk score of ≥ 5 points based on a published dedicated PVI risk score and a pre-angiographic estimated glomerular filtration rate (eGFR) \< 60 ml/min/1.73 m² 4. Both angiographic strategies seem feasible at the investigator's discretion 5. Age 18 years or older 6. Written informed consent Exclusion Criteria: 1. Very agitated patients 2. Patients with planned full anaesthesia during procedure 3. Patients with a life-expectancy less than one year 4. Patients confined to bed that are completely non-ambulatory 5. Known acute renal failure or known unstable renal function as evidenced by a recent increase in serum creatinine (SCr) of \> 0.5 mg/dl or \> 25% within 7 days 6. Iodinated contrast medium exposure within 7 days prior to procedure with change in SCr ≥ 0.1 mg/dl on two SCr measures ≥ 24 h apart 7. Advanced chronic kidney disease (CKD) with an eGFR \< 30 ml/min/1.73m² and/or dialysis 8. Current use of nephrotoxic agents (aminoglycoside antibiotics, sulfonamides, amphotericin B, or pentamidine), or an active chemotherapy agent 9. Acute or chronic pulmonary disease requiring oxygen therapy 10. Patients with known patent foramen ovale or atrial septal defect 11. Patients with planned nitrous oxide anaesthesia during intervention 12. Patients with manifest hyperthyroidism or manifest thyrotoxicosis 13. Known allergies or hypersensitivity to iodinated contrast media that cannot be adequately pre-treated prior to index procedure 14. Patients with decompensated heart failure 15. Patients with manifest tetany 16. Planned further procedure with a need for \> 10 ml of iodinated contrast medium (CM) in any location (e.g., CT scan, coronary angiography) within a period of 90 days 17. Any surgical procedure (except minor amputations) or intervention performed within 30 days prior to or planned within 90 days post index procedure 18. Fertile women (within two years of their last menstruation) without appropriate contraceptive measures (implanon, injections, oral contraceptives, intrauterine devices, partner with vasectomy) until day 30 after PVI. 19. Participation in other interventional trials. Exceptions are described in the trial protocol. 20. Suspected lack of compliance 21. Pregnant or nursing women