Randomised controlled trial to evaluate the effect of contrast material dilution on renal function in patients after endovascular aortic repair: rationale and design for the CULTURE trial

INTRODUCTION: Postoperative renal function decline is a major concern for thoracic endovascular aortic repair (TEVAR) and endovascular abdominal aortic repair (EVAR). Diluting contrast medium in the power injector may be helpful in reducing the risk of contrast-induced nephropathy, but it can also blur fluoroscopic vision during surgery. The quality of the current evidence is very low; thus, this study is designed to investigate the effect of contrast dilution in the power injector on renal function changes in patients after endovascular aortic repair. METHOD AND ANALYSIS: The study is a prospective, single-blind, parallel, non-inferiority, randomised controlled trial with two independent cohorts: Cohort TEVAR and EVAR. Individuals will enter the appropriate cohort based on clinical interviews if they meet the eligibility criteria. Participants in Cohort TEVAR and EVAR will be randomly allocated to the intervention group (diluting contrast medium to 50% in the power injector) and control group (pure contrast medium in the power injector) separately in a 1:1 ratio. The primary study points consist of the proportion of patients who develop acute kidney injury within 48 hours after TEAVR or EVAR (first stage) and freedom of major adverse kidney events at 12 months after TEAVR or EVAR (second stage). The safety endpoint is freedom of all types of endoleaks at 30 days after TEVAR or EVAR. Follow-up will be conducted at 30 days and 12 months after intervention. ETHICS AND DISSEMINATION: The trial was approved by the Ethics Committee on Biomedical Research, West China Hospital of Sichuan University (approval number: 20201290). The results of the study will be disseminated through publications in peer-reviewed journals and presentations at academic conferences. TRIAL REGISTRATION NUMBER: Chinese Clinical Trial Registry (ChiCTR2100042555).