Effects of remote ischaemic preconditioning against acute kidney injury in cardiac surgery patients: a randomized controlled trial

BACKGROUND: Acute kidney injury (AKI) is a well-known, serious complication of cardiac surgery that is associated with increased morbidity and mortality. However, the effects of remote ischaemic preconditioning (RIPC) on AKI after cardiac surgery have shown inconsistent results. This study was conducted to evaluate the effects of RIPC on AKI in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB). METHODS: In this single-centre, prospective, randomized, double-blind, controlled trial, 240 patients undergoing elective cardiac surgery were assessed for eligibility. 180 patients were randomly assigned to either RIPC group or control (Con) group. Finally, 159 patients (79 to Con group and 80 to RIPC group) completed follow-up. RIPC was performed on an upper limb with repeated 5-min inflation and 5-min deflation for three times. The primary outcome was the proportion of AKI 48 h after surgery. Secondary outcomes included major clinical short-term outcomes and the incidences of postoperative complications, clinical diagnostic indicators serum creatinine (SCr), urinary novel biomarkers IGFBP7 and TIMP-2. RESULTS: The proportion of AKI in RIPC group was significantly lower than Con group (Con versus RIPC: 26.6% vs. 13.8%; P = 0.044). In addition, RIPC resulted in a smaller increase in SCr levels 24 h (Con versus RIPC: 96.6 ± 35.9 µmol/L vs. 86.2 ± 24.9 µmol/L; P = 0.035) and 48 h (Con versus RIPC: 93.6 ± 45.2 µmol/L vs. 75.8 ± 30.8 µmol/L; P = 0.004) postoperatively. The postoperative concentrations of urinary biomarkers such as IGFBP7 and IGFBP7×TIMP-2 were lower in the RIPC group than in the Con group (P = 0.045 and 0.009, respectively). There were no significant differences in short-term outcomes and postoperative complications. CONCLUSIONS: In this trial, RIPC reduced the proportion of AKI and the amplitude of SCr elevation 48 h postoperatively. RIPC may exert a certain renal protective effect by enhancing renal recovery in the early postoperative stage. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT04433468.