Relationship between a perioperative intravenous fluid administration strategy and acute kidney injury following off-pump coronary artery bypass surgery: an observational study

INTRODUCTION Saline-based and hydroxyethyl starch solutions are associated with increased risk of renal dysfunction. In the present study, we tested the hypothesis that balanced solutions and a limited volume of hydroxyethyl starch solution (renal protective fluid management [RPF] strategy) would decrease the incidence of postoperative acute kidney injury (AKI) and improve clinical outcomes in patients undergoing off-pump coronary artery bypass graft surgery (OPCAB). METHODS We investigated 783 patients who underwent elective OPCAB. All patients who underwent OPCAB between 1 January 2010 and 4 July 2012 formed the control group and were given intravenous fluids with saline-based solutions and unlimited volumes of colloid solutions. All patients who underwent OPCAB between 5 July 2012 and 31 December 2013 formed the RPF group and were given intravenous fluids with RPF. The primary outcome was the incidence of postoperative AKI. Secondary outcomes included the incidence of severe AKI, requirement for renal replacement therapy, renal outcome at the time of discharge, and other clinical outcomes. RESULTS Postoperative AKI occurred in 33 patients (14.4 %) in the RPF group compared with 210 patients (37.9 %) in the control group (P < 0.001). The incidences of severe AKI and persistent AKI after OPCAB were significantly lower, and the postoperative extubation time and duration of hospital stay were significantly shorter, in patients in the RPF group than in those in the control group. After adjustment by multivariate regression analyses and inverse probability of treatment weighting adjustment, the RPF group was independently associated with a lower incidence of postoperative AKI, severe AKI, and persistent AKI and a shorter postoperative extubation time and duration of hospital stay. CONCLUSIONS The RPF strategy is associated with a significantly decreased incidence of postoperative, severe, and persistent AKI in patients undergoing OPCAB, although residual confounding may be present.