BEdside ultraSound-guided ulTrafiltration for Acute Kidney Injury patients receiving CRRT: protocol for a randomised controlled trial (the BEST-AKI study)

INTRODUCTION: The mortality of critical acute kidney injury (AKI) patients requiring continuous renal replacement therapy (CRRT) is estimated to be as high as 50%. Fluid overload (FO) is a leading factor contributing to poor prognosis. CRRT, aimed at removing excessive water and toxins from the body, is an efficient method to address FO. However, accurate ultrafiltration is challenging because of the difficulty of quantifying fluid status, which usually relies on traditional examinations and clinicians' perceptions. Both overultrafiltration and underultrafiltration are associated with adverse events. Critical care ultrasound (CCUS), introduced as a non-invasive tool, might be promising for assessing the volume status of AKI. However, there has been no solid evidence on the application of bedside CCUS in directing CRRT ultrafiltration among AKI patients. Therefore, in this randomised controlled trial (RCT), we aimed to investigate the efficacy and reliability of BEdside ultraSound-guided ultrafiltration (BEST) in comparison with conventional methods for AKI patients receiving CRRT. METHODS AND ANALYSIS: This study is a single-centre, prospective, parallel-group, open-label RCT involving AKI patients who receive CRRT due to FO in the intensive care unit of a university-affiliated medical centre from September 2024. A total of 132 patients will be enrolled and randomly assigned to receive either bedside CCUS via an integrated score combining vascular, lung and cardiac ultrasonography or traditional methods to assess the volume status and guide CRRT ultrafiltration. The FO status will be quantified using a novel BEST score, where 1 point will be given if the inferior vena cava diameter >2.1 cm, 2 or more positive lung regions (B-line score >3) are identified under lung ultrasound, or E/e' >14 under echocardiography, with a total score of 3. The primary outcome is the rate of resuming euvolaemic status at the 72nd hour, on day 7 and at the end of CRRT. The secondary outcomes encompass the rates of FO correction, in-hospital events, renal outcomes, patient mortality and rehospitalisation. ETHICS AND DISSEMINATION: The Institutional Review Board of West China Hospital, Sichuan University, granted ethical approval for this study (protocol version 2 dated 3 June 2024; Approval No. of the ethics committee: 2024-919). All participants or their legal representatives will sign the informed written consent. We intend to disseminate these findings to participants, medical practitioners, the public and other interested parties via conference presentations and publications without imposing any restrictions. TRIAL REGISTRATION NUMBER: ChiCTR2400087833.